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vlink="#840084" alink="#0000FF"> 29<div class="navheader"> 30<table width="100%" summary="Navigation header"> 31<tr><th colspan="3" align="center">Chapter�6.�<acronym class="acronym">BIND</acronym> 9 Configuration Reference</th></tr> 32<tr> 33<td width="20%" align="left"> 34<a accesskey="p" href="Bv9ARM.ch05.html">Prev</a>�</td> 35<th width="60%" align="center">�</th> 36<td width="20%" align="right">�<a accesskey="n" href="Bv9ARM.ch07.html">Next</a> 37</td> 38</tr> 39</table> 40<hr> 41</div> 42<div class="chapter" lang="en"> 43<div class="titlepage"><div><div><h2 class="title"> 44<a name="Bv9ARM.ch06"></a>Chapter�6.�<acronym class="acronym">BIND</acronym> 9 Configuration Reference</h2></div></div></div> 45<div class="toc"> 46<p><b>Table of Contents</b></p> 47<dl> 48<dt><span class="sect1"><a href="Bv9ARM.ch06.html#configuration_file_elements">Configuration File Elements</a></span></dt> 49<dd><dl> 50<dt><span class="sect2"><a href="Bv9ARM.ch06.html#address_match_lists">Address Match Lists</a></span></dt> 51<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574332">Comment Syntax</a></span></dt> 52</dl></dd> 53<dt><span class="sect1"><a href="Bv9ARM.ch06.html#Configuration_File_Grammar">Configuration File Grammar</a></span></dt> 54<dd><dl> 55<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2574986"><span><strong class="command">acl</strong></span> Statement Grammar</a></span></dt> 56<dt><span class="sect2"><a href="Bv9ARM.ch06.html#acl"><span><strong class="command">acl</strong></span> Statement Definition and 57 Usage</a></span></dt> 58<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575176"><span><strong class="command">controls</strong></span> Statement Grammar</a></span></dt> 59<dt><span class="sect2"><a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage"><span><strong class="command">controls</strong></span> Statement Definition and 60 Usage</a></span></dt> 61<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575467"><span><strong class="command">include</strong></span> Statement Grammar</a></span></dt> 62<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575484"><span><strong class="command">include</strong></span> Statement Definition and 63 Usage</a></span></dt> 64<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575576"><span><strong class="command">key</strong></span> Statement Grammar</a></span></dt> 65<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575600"><span><strong class="command">key</strong></span> Statement Definition and Usage</a></span></dt> 66<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575758"><span><strong class="command">logging</strong></span> Statement Grammar</a></span></dt> 67<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2575884"><span><strong class="command">logging</strong></span> Statement Definition and 68 Usage</a></span></dt> 69<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577910"><span><strong class="command">lwres</strong></span> Statement Grammar</a></span></dt> 70<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2577984"><span><strong class="command">lwres</strong></span> Statement Definition and Usage</a></span></dt> 71<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578116"><span><strong class="command">masters</strong></span> Statement Grammar</a></span></dt> 72<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578160"><span><strong class="command">masters</strong></span> Statement Definition and 73 Usage</a></span></dt> 74<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2578174"><span><strong class="command">options</strong></span> Statement Grammar</a></span></dt> 75<dt><span class="sect2"><a href="Bv9ARM.ch06.html#options"><span><strong class="command">options</strong></span> Statement Definition and 76 Usage</a></span></dt> 77<dt><span class="sect2"><a href="Bv9ARM.ch06.html#server_statement_grammar"><span><strong class="command">server</strong></span> Statement Grammar</a></span></dt> 78<dt><span class="sect2"><a href="Bv9ARM.ch06.html#server_statement_definition_and_usage"><span><strong class="command">server</strong></span> Statement Definition and 79 Usage</a></span></dt> 80<dt><span class="sect2"><a href="Bv9ARM.ch06.html#statschannels"><span><strong class="command">statistics-channels</strong></span> Statement Grammar</a></span></dt> 81<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2589481"><span><strong class="command">statistics-channels</strong></span> Statement Definition and 82 Usage</a></span></dt> 83<dt><span class="sect2"><a href="Bv9ARM.ch06.html#trusted-keys"><span><strong class="command">trusted-keys</strong></span> Statement Grammar</a></span></dt> 84<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2589689"><span><strong class="command">trusted-keys</strong></span> Statement Definition 85 and Usage</a></span></dt> 86<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2589736"><span><strong class="command">managed-keys</strong></span> Statement Grammar</a></span></dt> 87<dt><span class="sect2"><a href="Bv9ARM.ch06.html#managed-keys"><span><strong class="command">managed-keys</strong></span> Statement Definition 88 and Usage</a></span></dt> 89<dt><span class="sect2"><a href="Bv9ARM.ch06.html#view_statement_grammar"><span><strong class="command">view</strong></span> Statement Grammar</a></span></dt> 90<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2590162"><span><strong class="command">view</strong></span> Statement Definition and Usage</a></span></dt> 91<dt><span class="sect2"><a href="Bv9ARM.ch06.html#zone_statement_grammar"><span><strong class="command">zone</strong></span> 92 Statement Grammar</a></span></dt> 93<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2591713"><span><strong class="command">zone</strong></span> Statement Definition and Usage</a></span></dt> 94</dl></dd> 95<dt><span class="sect1"><a href="Bv9ARM.ch06.html#id2595116">Zone File</a></span></dt> 96<dd><dl> 97<dt><span class="sect2"><a href="Bv9ARM.ch06.html#types_of_resource_records_and_when_to_use_them">Types of Resource Records and When to Use Them</a></span></dt> 98<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2597415">Discussion of MX Records</a></span></dt> 99<dt><span class="sect2"><a href="Bv9ARM.ch06.html#Setting_TTLs">Setting TTLs</a></span></dt> 100<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2597962">Inverse Mapping in IPv4</a></span></dt> 101<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2598157">Other Zone File Directives</a></span></dt> 102<dt><span class="sect2"><a href="Bv9ARM.ch06.html#id2598430"><acronym class="acronym">BIND</acronym> Master File Extension: the <span><strong class="command">$GENERATE</strong></span> Directive</a></span></dt> 103<dt><span class="sect2"><a href="Bv9ARM.ch06.html#zonefile_format">Additional File Formats</a></span></dt> 104</dl></dd> 105<dt><span class="sect1"><a href="Bv9ARM.ch06.html#statistics">BIND9 Statistics</a></span></dt> 106<dd><dl><dt><span class="sect2"><a href="Bv9ARM.ch06.html#statistics_counters">Statistics Counters</a></span></dt></dl></dd> 107</dl> 108</div> 109<p> 110 <acronym class="acronym">BIND</acronym> 9 configuration is broadly similar 111 to <acronym class="acronym">BIND</acronym> 8; however, there are a few new 112 areas 113 of configuration, such as views. <acronym class="acronym">BIND</acronym> 114 8 configuration files should work with few alterations in <acronym class="acronym">BIND</acronym> 115 9, although more complex configurations should be reviewed to check 116 if they can be more efficiently implemented using the new features 117 found in <acronym class="acronym">BIND</acronym> 9. 118 </p> 119<p> 120 <acronym class="acronym">BIND</acronym> 4 configuration files can be 121 converted to the new format 122 using the shell script 123 <code class="filename">contrib/named-bootconf/named-bootconf.sh</code>. 124 </p> 125<div class="sect1" lang="en"> 126<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 127<a name="configuration_file_elements"></a>Configuration File Elements</h2></div></div></div> 128<p> 129 Following is a list of elements used throughout the <acronym class="acronym">BIND</acronym> configuration 130 file documentation: 131 </p> 132<div class="informaltable"><table border="1"> 133<colgroup> 134<col> 135<col> 136</colgroup> 137<tbody> 138<tr> 139<td> 140 <p> 141 <code class="varname">acl_name</code> 142 </p> 143 </td> 144<td> 145 <p> 146 The name of an <code class="varname">address_match_list</code> as 147 defined by the <span><strong class="command">acl</strong></span> statement. 148 </p> 149 </td> 150</tr> 151<tr> 152<td> 153 <p> 154 <code class="varname">address_match_list</code> 155 </p> 156 </td> 157<td> 158 <p> 159 A list of one or more 160 <code class="varname">ip_addr</code>, 161 <code class="varname">ip_prefix</code>, <code class="varname">key_id</code>, 162 or <code class="varname">acl_name</code> elements, see 163 <a href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called “Address Match Lists”</a>. 164 </p> 165 </td> 166</tr> 167<tr> 168<td> 169 <p> 170 <code class="varname">masters_list</code> 171 </p> 172 </td> 173<td> 174 <p> 175 A named list of one or more <code class="varname">ip_addr</code> 176 with optional <code class="varname">key_id</code> and/or 177 <code class="varname">ip_port</code>. 178 A <code class="varname">masters_list</code> may include other 179 <code class="varname">masters_lists</code>. 180 </p> 181 </td> 182</tr> 183<tr> 184<td> 185 <p> 186 <code class="varname">domain_name</code> 187 </p> 188 </td> 189<td> 190 <p> 191 A quoted string which will be used as 192 a DNS name, for example "<code class="literal">my.test.domain</code>". 193 </p> 194 </td> 195</tr> 196<tr> 197<td> 198 <p> 199 <code class="varname">namelist</code> 200 </p> 201 </td> 202<td> 203 <p> 204 A list of one or more <code class="varname">domain_name</code> 205 elements. 206 </p> 207 </td> 208</tr> 209<tr> 210<td> 211 <p> 212 <code class="varname">dotted_decimal</code> 213 </p> 214 </td> 215<td> 216 <p> 217 One to four integers valued 0 through 218 255 separated by dots (`.'), such as <span><strong class="command">123</strong></span>, 219 <span><strong class="command">45.67</strong></span> or <span><strong class="command">89.123.45.67</strong></span>. 220 </p> 221 </td> 222</tr> 223<tr> 224<td> 225 <p> 226 <code class="varname">ip4_addr</code> 227 </p> 228 </td> 229<td> 230 <p> 231 An IPv4 address with exactly four elements 232 in <code class="varname">dotted_decimal</code> notation. 233 </p> 234 </td> 235</tr> 236<tr> 237<td> 238 <p> 239 <code class="varname">ip6_addr</code> 240 </p> 241 </td> 242<td> 243 <p> 244 An IPv6 address, such as <span><strong class="command">2001:db8::1234</strong></span>. 245 IPv6 scoped addresses that have ambiguity on their 246 scope zones must be disambiguated by an appropriate 247 zone ID with the percent character (`%') as 248 delimiter. It is strongly recommended to use 249 string zone names rather than numeric identifiers, 250 in order to be robust against system configuration 251 changes. However, since there is no standard 252 mapping for such names and identifier values, 253 currently only interface names as link identifiers 254 are supported, assuming one-to-one mapping between 255 interfaces and links. For example, a link-local 256 address <span><strong class="command">fe80::1</strong></span> on the link 257 attached to the interface <span><strong class="command">ne0</strong></span> 258 can be specified as <span><strong class="command">fe80::1%ne0</strong></span>. 259 Note that on most systems link-local addresses 260 always have the ambiguity, and need to be 261 disambiguated. 262 </p> 263 </td> 264</tr> 265<tr> 266<td> 267 <p> 268 <code class="varname">ip_addr</code> 269 </p> 270 </td> 271<td> 272 <p> 273 An <code class="varname">ip4_addr</code> or <code class="varname">ip6_addr</code>. 274 </p> 275 </td> 276</tr> 277<tr> 278<td> 279 <p> 280 <code class="varname">ip_port</code> 281 </p> 282 </td> 283<td> 284 <p> 285 An IP port <code class="varname">number</code>. 286 The <code class="varname">number</code> is limited to 0 287 through 65535, with values 288 below 1024 typically restricted to use by processes running 289 as root. 290 In some cases, an asterisk (`*') character can be used as a 291 placeholder to 292 select a random high-numbered port. 293 </p> 294 </td> 295</tr> 296<tr> 297<td> 298 <p> 299 <code class="varname">ip_prefix</code> 300 </p> 301 </td> 302<td> 303 <p> 304 An IP network specified as an <code class="varname">ip_addr</code>, 305 followed by a slash (`/') and then the number of bits in the 306 netmask. 307 Trailing zeros in a <code class="varname">ip_addr</code> 308 may omitted. 309 For example, <span><strong class="command">127/8</strong></span> is the 310 network <span><strong class="command">127.0.0.0</strong></span> with 311 netmask <span><strong class="command">255.0.0.0</strong></span> and <span><strong class="command">1.2.3.0/28</strong></span> is 312 network <span><strong class="command">1.2.3.0</strong></span> with netmask <span><strong class="command">255.255.255.240</strong></span>. 313 </p> 314 <p> 315 When specifying a prefix involving a IPv6 scoped address 316 the scope may be omitted. In that case the prefix will 317 match packets from any scope. 318 </p> 319 </td> 320</tr> 321<tr> 322<td> 323 <p> 324 <code class="varname">key_id</code> 325 </p> 326 </td> 327<td> 328 <p> 329 A <code class="varname">domain_name</code> representing 330 the name of a shared key, to be used for transaction 331 security. 332 </p> 333 </td> 334</tr> 335<tr> 336<td> 337 <p> 338 <code class="varname">key_list</code> 339 </p> 340 </td> 341<td> 342 <p> 343 A list of one or more 344 <code class="varname">key_id</code>s, 345 separated by semicolons and ending with a semicolon. 346 </p> 347 </td> 348</tr> 349<tr> 350<td> 351 <p> 352 <code class="varname">number</code> 353 </p> 354 </td> 355<td> 356 <p> 357 A non-negative 32-bit integer 358 (i.e., a number between 0 and 4294967295, inclusive). 359 Its acceptable value might further 360 be limited by the context in which it is used. 361 </p> 362 </td> 363</tr> 364<tr> 365<td> 366 <p> 367 <code class="varname">path_name</code> 368 </p> 369 </td> 370<td> 371 <p> 372 A quoted string which will be used as 373 a pathname, such as <code class="filename">zones/master/my.test.domain</code>. 374 </p> 375 </td> 376</tr> 377<tr> 378<td> 379 <p> 380 <code class="varname">port_list</code> 381 </p> 382 </td> 383<td> 384 <p> 385 A list of an <code class="varname">ip_port</code> or a port 386 range. 387 A port range is specified in the form of 388 <strong class="userinput"><code>range</code></strong> followed by 389 two <code class="varname">ip_port</code>s, 390 <code class="varname">port_low</code> and 391 <code class="varname">port_high</code>, which represents 392 port numbers from <code class="varname">port_low</code> through 393 <code class="varname">port_high</code>, inclusive. 394 <code class="varname">port_low</code> must not be larger than 395 <code class="varname">port_high</code>. 396 For example, 397 <strong class="userinput"><code>range 1024 65535</code></strong> represents 398 ports from 1024 through 65535. 399 In either case an asterisk (`*') character is not 400 allowed as a valid <code class="varname">ip_port</code>. 401 </p> 402 </td> 403</tr> 404<tr> 405<td> 406 <p> 407 <code class="varname">size_spec</code> 408 </p> 409 </td> 410<td> 411 <p> 412 A number, the word <strong class="userinput"><code>unlimited</code></strong>, 413 or the word <strong class="userinput"><code>default</code></strong>. 414 </p> 415 <p> 416 An <code class="varname">unlimited</code> <code class="varname">size_spec</code> requests unlimited 417 use, or the maximum available amount. A <code class="varname">default size_spec</code> uses 418 the limit that was in force when the server was started. 419 </p> 420 <p> 421 A <code class="varname">number</code> can optionally be 422 followed by a scaling factor: 423 <strong class="userinput"><code>K</code></strong> or <strong class="userinput"><code>k</code></strong> 424 for kilobytes, 425 <strong class="userinput"><code>M</code></strong> or <strong class="userinput"><code>m</code></strong> 426 for megabytes, and 427 <strong class="userinput"><code>G</code></strong> or <strong class="userinput"><code>g</code></strong> for gigabytes, 428 which scale by 1024, 1024*1024, and 1024*1024*1024 429 respectively. 430 </p> 431 <p> 432 The value must be representable as a 64-bit unsigned integer 433 (0 to 18446744073709551615, inclusive). 434 Using <code class="varname">unlimited</code> is the best 435 way 436 to safely set a really large number. 437 </p> 438 </td> 439</tr> 440<tr> 441<td> 442 <p> 443 <code class="varname">yes_or_no</code> 444 </p> 445 </td> 446<td> 447 <p> 448 Either <strong class="userinput"><code>yes</code></strong> or <strong class="userinput"><code>no</code></strong>. 449 The words <strong class="userinput"><code>true</code></strong> and <strong class="userinput"><code>false</code></strong> are 450 also accepted, as are the numbers <strong class="userinput"><code>1</code></strong> 451 and <strong class="userinput"><code>0</code></strong>. 452 </p> 453 </td> 454</tr> 455<tr> 456<td> 457 <p> 458 <code class="varname">dialup_option</code> 459 </p> 460 </td> 461<td> 462 <p> 463 One of <strong class="userinput"><code>yes</code></strong>, 464 <strong class="userinput"><code>no</code></strong>, <strong class="userinput"><code>notify</code></strong>, 465 <strong class="userinput"><code>notify-passive</code></strong>, <strong class="userinput"><code>refresh</code></strong> or 466 <strong class="userinput"><code>passive</code></strong>. 467 When used in a zone, <strong class="userinput"><code>notify-passive</code></strong>, 468 <strong class="userinput"><code>refresh</code></strong>, and <strong class="userinput"><code>passive</code></strong> 469 are restricted to slave and stub zones. 470 </p> 471 </td> 472</tr> 473</tbody> 474</table></div> 475<div class="sect2" lang="en"> 476<div class="titlepage"><div><div><h3 class="title"> 477<a name="address_match_lists"></a>Address Match Lists</h3></div></div></div> 478<div class="sect3" lang="en"> 479<div class="titlepage"><div><div><h4 class="title"> 480<a name="id2574099"></a>Syntax</h4></div></div></div> 481<pre class="programlisting"><code class="varname">address_match_list</code> = address_match_list_element ; 482 [<span class="optional"> address_match_list_element; ... </span>] 483<code class="varname">address_match_list_element</code> = [<span class="optional"> ! </span>] (ip_address [<span class="optional">/length</span>] | 484 key key_id | acl_name | { address_match_list } ) 485</pre> 486</div> 487<div class="sect3" lang="en"> 488<div class="titlepage"><div><div><h4 class="title"> 489<a name="id2574126"></a>Definition and Usage</h4></div></div></div> 490<p> 491 Address match lists are primarily used to determine access 492 control for various server operations. They are also used in 493 the <span><strong class="command">listen-on</strong></span> and <span><strong class="command">sortlist</strong></span> 494 statements. The elements which constitute an address match 495 list can be any of the following: 496 </p> 497<div class="itemizedlist"><ul type="disc"> 498<li>an IP address (IPv4 or IPv6)</li> 499<li>an IP prefix (in `/' notation)</li> 500<li> 501 a key ID, as defined by the <span><strong class="command">key</strong></span> 502 statement 503 </li> 504<li>the name of an address match list defined with 505 the <span><strong class="command">acl</strong></span> statement 506 </li> 507<li>a nested address match list enclosed in braces</li> 508</ul></div> 509<p> 510 Elements can be negated with a leading exclamation mark (`!'), 511 and the match list names "any", "none", "localhost", and 512 "localnets" are predefined. More information on those names 513 can be found in the description of the acl statement. 514 </p> 515<p> 516 The addition of the key clause made the name of this syntactic 517 element something of a misnomer, since security keys can be used 518 to validate access without regard to a host or network address. 519 Nonetheless, the term "address match list" is still used 520 throughout the documentation. 521 </p> 522<p> 523 When a given IP address or prefix is compared to an address 524 match list, the comparison takes place in approximately O(1) 525 time. However, key comparisons require that the list of keys 526 be traversed until a matching key is found, and therefore may 527 be somewhat slower. 528 </p> 529<p> 530 The interpretation of a match depends on whether the list is being 531 used for access control, defining <span><strong class="command">listen-on</strong></span> ports, or in a 532 <span><strong class="command">sortlist</strong></span>, and whether the element was negated. 533 </p> 534<p> 535 When used as an access control list, a non-negated match 536 allows access and a negated match denies access. If 537 there is no match, access is denied. The clauses 538 <span><strong class="command">allow-notify</strong></span>, 539 <span><strong class="command">allow-recursion</strong></span>, 540 <span><strong class="command">allow-recursion-on</strong></span>, 541 <span><strong class="command">allow-query</strong></span>, 542 <span><strong class="command">allow-query-on</strong></span>, 543 <span><strong class="command">allow-query-cache</strong></span>, 544 <span><strong class="command">allow-query-cache-on</strong></span>, 545 <span><strong class="command">allow-transfer</strong></span>, 546 <span><strong class="command">allow-update</strong></span>, 547 <span><strong class="command">allow-update-forwarding</strong></span>, and 548 <span><strong class="command">blackhole</strong></span> all use address match 549 lists. Similarly, the <span><strong class="command">listen-on</strong></span> option will cause the 550 server to refuse queries on any of the machine's 551 addresses which do not match the list. 552 </p> 553<p> 554 Order of insertion is significant. If more than one element 555 in an ACL is found to match a given IP address or prefix, 556 preference will be given to the one that came 557 <span class="emphasis"><em>first</em></span> in the ACL definition. 558 Because of this first-match behavior, an element that 559 defines a subset of another element in the list should 560 come before the broader element, regardless of whether 561 either is negated. For example, in 562 <span><strong class="command">1.2.3/24; ! 1.2.3.13;</strong></span> 563 the 1.2.3.13 element is completely useless because the 564 algorithm will match any lookup for 1.2.3.13 to the 1.2.3/24 565 element. Using <span><strong class="command">! 1.2.3.13; 1.2.3/24</strong></span> fixes 566 that problem by having 1.2.3.13 blocked by the negation, but 567 all other 1.2.3.* hosts fall through. 568 </p> 569</div> 570</div> 571<div class="sect2" lang="en"> 572<div class="titlepage"><div><div><h3 class="title"> 573<a name="id2574332"></a>Comment Syntax</h3></div></div></div> 574<p> 575 The <acronym class="acronym">BIND</acronym> 9 comment syntax allows for 576 comments to appear 577 anywhere that whitespace may appear in a <acronym class="acronym">BIND</acronym> configuration 578 file. To appeal to programmers of all kinds, they can be written 579 in the C, C++, or shell/perl style. 580 </p> 581<div class="sect3" lang="en"> 582<div class="titlepage"><div><div><h4 class="title"> 583<a name="id2574347"></a>Syntax</h4></div></div></div> 584<p> 585 </p> 586<pre class="programlisting">/* This is a <acronym class="acronym">BIND</acronym> comment as in C */</pre> 587<p> 588 </p> 589<pre class="programlisting">// This is a <acronym class="acronym">BIND</acronym> comment as in C++</pre> 590<p> 591 </p> 592<pre class="programlisting"># This is a <acronym class="acronym">BIND</acronym> comment as in common UNIX shells 593# and perl</pre> 594<p> 595 </p> 596</div> 597<div class="sect3" lang="en"> 598<div class="titlepage"><div><div><h4 class="title"> 599<a name="id2574377"></a>Definition and Usage</h4></div></div></div> 600<p> 601 Comments may appear anywhere that whitespace may appear in 602 a <acronym class="acronym">BIND</acronym> configuration file. 603 </p> 604<p> 605 C-style comments start with the two characters /* (slash, 606 star) and end with */ (star, slash). Because they are completely 607 delimited with these characters, they can be used to comment only 608 a portion of a line or to span multiple lines. 609 </p> 610<p> 611 C-style comments cannot be nested. For example, the following 612 is not valid because the entire comment ends with the first */: 613 </p> 614<p> 615 616</p> 617<pre class="programlisting">/* This is the start of a comment. 618 This is still part of the comment. 619/* This is an incorrect attempt at nesting a comment. */ 620 This is no longer in any comment. */ 621</pre> 622<p> 623 624 </p> 625<p> 626 C++-style comments start with the two characters // (slash, 627 slash) and continue to the end of the physical line. They cannot 628 be continued across multiple physical lines; to have one logical 629 comment span multiple lines, each line must use the // pair. 630 For example: 631 </p> 632<p> 633 634</p> 635<pre class="programlisting">// This is the start of a comment. The next line 636// is a new comment, even though it is logically 637// part of the previous comment. 638</pre> 639<p> 640 641 </p> 642<p> 643 Shell-style (or perl-style, if you prefer) comments start 644 with the character <code class="literal">#</code> (number sign) 645 and continue to the end of the 646 physical line, as in C++ comments. 647 For example: 648 </p> 649<p> 650 651</p> 652<pre class="programlisting"># This is the start of a comment. The next line 653# is a new comment, even though it is logically 654# part of the previous comment. 655</pre> 656<p> 657 658 </p> 659<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> 660<h3 class="title">Warning</h3> 661<p> 662 You cannot use the semicolon (`;') character 663 to start a comment such as you would in a zone file. The 664 semicolon indicates the end of a configuration 665 statement. 666 </p> 667</div> 668</div> 669</div> 670</div> 671<div class="sect1" lang="en"> 672<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 673<a name="Configuration_File_Grammar"></a>Configuration File Grammar</h2></div></div></div> 674<p> 675 A <acronym class="acronym">BIND</acronym> 9 configuration consists of 676 statements and comments. 677 Statements end with a semicolon. Statements and comments are the 678 only elements that can appear without enclosing braces. Many 679 statements contain a block of sub-statements, which are also 680 terminated with a semicolon. 681 </p> 682<p> 683 The following statements are supported: 684 </p> 685<div class="informaltable"><table border="1"> 686<colgroup> 687<col> 688<col> 689</colgroup> 690<tbody> 691<tr> 692<td> 693 <p><span><strong class="command">acl</strong></span></p> 694 </td> 695<td> 696 <p> 697 defines a named IP address 698 matching list, for access control and other uses. 699 </p> 700 </td> 701</tr> 702<tr> 703<td> 704 <p><span><strong class="command">controls</strong></span></p> 705 </td> 706<td> 707 <p> 708 declares control channels to be used 709 by the <span><strong class="command">rndc</strong></span> utility. 710 </p> 711 </td> 712</tr> 713<tr> 714<td> 715 <p><span><strong class="command">include</strong></span></p> 716 </td> 717<td> 718 <p> 719 includes a file. 720 </p> 721 </td> 722</tr> 723<tr> 724<td> 725 <p><span><strong class="command">key</strong></span></p> 726 </td> 727<td> 728 <p> 729 specifies key information for use in 730 authentication and authorization using TSIG. 731 </p> 732 </td> 733</tr> 734<tr> 735<td> 736 <p><span><strong class="command">logging</strong></span></p> 737 </td> 738<td> 739 <p> 740 specifies what the server logs, and where 741 the log messages are sent. 742 </p> 743 </td> 744</tr> 745<tr> 746<td> 747 <p><span><strong class="command">lwres</strong></span></p> 748 </td> 749<td> 750 <p> 751 configures <span><strong class="command">named</strong></span> to 752 also act as a light-weight resolver daemon (<span><strong class="command">lwresd</strong></span>). 753 </p> 754 </td> 755</tr> 756<tr> 757<td> 758 <p><span><strong class="command">masters</strong></span></p> 759 </td> 760<td> 761 <p> 762 defines a named masters list for 763 inclusion in stub and slave zone masters clauses. 764 </p> 765 </td> 766</tr> 767<tr> 768<td> 769 <p><span><strong class="command">options</strong></span></p> 770 </td> 771<td> 772 <p> 773 controls global server configuration 774 options and sets defaults for other statements. 775 </p> 776 </td> 777</tr> 778<tr> 779<td> 780 <p><span><strong class="command">server</strong></span></p> 781 </td> 782<td> 783 <p> 784 sets certain configuration options on 785 a per-server basis. 786 </p> 787 </td> 788</tr> 789<tr> 790<td> 791 <p><span><strong class="command">statistics-channels</strong></span></p> 792 </td> 793<td> 794 <p> 795 declares communication channels to get access to 796 <span><strong class="command">named</strong></span> statistics. 797 </p> 798 </td> 799</tr> 800<tr> 801<td> 802 <p><span><strong class="command">trusted-keys</strong></span></p> 803 </td> 804<td> 805 <p> 806 defines trusted DNSSEC keys. 807 </p> 808 </td> 809</tr> 810<tr> 811<td> 812 <p><span><strong class="command">managed-keys</strong></span></p> 813 </td> 814<td> 815 <p> 816 lists DNSSEC keys to be kept up to date 817 using RFC 5011 trust anchor maintenance. 818 </p> 819 </td> 820</tr> 821<tr> 822<td> 823 <p><span><strong class="command">view</strong></span></p> 824 </td> 825<td> 826 <p> 827 defines a view. 828 </p> 829 </td> 830</tr> 831<tr> 832<td> 833 <p><span><strong class="command">zone</strong></span></p> 834 </td> 835<td> 836 <p> 837 defines a zone. 838 </p> 839 </td> 840</tr> 841</tbody> 842</table></div> 843<p> 844 The <span><strong class="command">logging</strong></span> and 845 <span><strong class="command">options</strong></span> statements may only occur once 846 per 847 configuration. 848 </p> 849<div class="sect2" lang="en"> 850<div class="titlepage"><div><div><h3 class="title"> 851<a name="id2574986"></a><span><strong class="command">acl</strong></span> Statement Grammar</h3></div></div></div> 852<pre class="programlisting"><span><strong class="command">acl</strong></span> acl-name { 853 address_match_list 854}; 855</pre> 856</div> 857<div class="sect2" lang="en"> 858<div class="titlepage"><div><div><h3 class="title"> 859<a name="acl"></a><span><strong class="command">acl</strong></span> Statement Definition and 860 Usage</h3></div></div></div> 861<p> 862 The <span><strong class="command">acl</strong></span> statement assigns a symbolic 863 name to an address match list. It gets its name from a primary 864 use of address match lists: Access Control Lists (ACLs). 865 </p> 866<p> 867 Note that an address match list's name must be defined 868 with <span><strong class="command">acl</strong></span> before it can be used 869 elsewhere; no forward references are allowed. 870 </p> 871<p> 872 The following ACLs are built-in: 873 </p> 874<div class="informaltable"><table border="1"> 875<colgroup> 876<col> 877<col> 878</colgroup> 879<tbody> 880<tr> 881<td> 882 <p><span><strong class="command">any</strong></span></p> 883 </td> 884<td> 885 <p> 886 Matches all hosts. 887 </p> 888 </td> 889</tr> 890<tr> 891<td> 892 <p><span><strong class="command">none</strong></span></p> 893 </td> 894<td> 895 <p> 896 Matches no hosts. 897 </p> 898 </td> 899</tr> 900<tr> 901<td> 902 <p><span><strong class="command">localhost</strong></span></p> 903 </td> 904<td> 905 <p> 906 Matches the IPv4 and IPv6 addresses of all network 907 interfaces on the system. 908 </p> 909 </td> 910</tr> 911<tr> 912<td> 913 <p><span><strong class="command">localnets</strong></span></p> 914 </td> 915<td> 916 <p> 917 Matches any host on an IPv4 or IPv6 network 918 for which the system has an interface. 919 Some systems do not provide a way to determine the prefix 920 lengths of 921 local IPv6 addresses. 922 In such a case, <span><strong class="command">localnets</strong></span> 923 only matches the local 924 IPv6 addresses, just like <span><strong class="command">localhost</strong></span>. 925 </p> 926 </td> 927</tr> 928</tbody> 929</table></div> 930</div> 931<div class="sect2" lang="en"> 932<div class="titlepage"><div><div><h3 class="title"> 933<a name="id2575176"></a><span><strong class="command">controls</strong></span> Statement Grammar</h3></div></div></div> 934<pre class="programlisting"><span><strong class="command">controls</strong></span> { 935 [ inet ( ip_addr | * ) [ port ip_port ] 936 allow { <em class="replaceable"><code> address_match_list </code></em> } 937 keys { <em class="replaceable"><code>key_list</code></em> }; ] 938 [ inet ...; ] 939 [ unix <em class="replaceable"><code>path</code></em> perm <em class="replaceable"><code>number</code></em> owner <em class="replaceable"><code>number</code></em> group <em class="replaceable"><code>number</code></em> 940 keys { <em class="replaceable"><code>key_list</code></em> }; ] 941 [ unix ...; ] 942}; 943</pre> 944</div> 945<div class="sect2" lang="en"> 946<div class="titlepage"><div><div><h3 class="title"> 947<a name="controls_statement_definition_and_usage"></a><span><strong class="command">controls</strong></span> Statement Definition and 948 Usage</h3></div></div></div> 949<p> 950 The <span><strong class="command">controls</strong></span> statement declares control 951 channels to be used by system administrators to control the 952 operation of the name server. These control channels are 953 used by the <span><strong class="command">rndc</strong></span> utility to send 954 commands to and retrieve non-DNS results from a name server. 955 </p> 956<p> 957 An <span><strong class="command">inet</strong></span> control channel is a TCP socket 958 listening at the specified <span><strong class="command">ip_port</strong></span> on the 959 specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6 960 address. An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is 961 interpreted as the IPv4 wildcard address; connections will be 962 accepted on any of the system's IPv4 addresses. 963 To listen on the IPv6 wildcard address, 964 use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>. 965 If you will only use <span><strong class="command">rndc</strong></span> on the local host, 966 using the loopback address (<code class="literal">127.0.0.1</code> 967 or <code class="literal">::1</code>) is recommended for maximum security. 968 </p> 969<p> 970 If no port is specified, port 953 is used. The asterisk 971 "<code class="literal">*</code>" cannot be used for <span><strong class="command">ip_port</strong></span>. 972 </p> 973<p> 974 The ability to issue commands over the control channel is 975 restricted by the <span><strong class="command">allow</strong></span> and 976 <span><strong class="command">keys</strong></span> clauses. 977 Connections to the control channel are permitted based on the 978 <span><strong class="command">address_match_list</strong></span>. This is for simple 979 IP address based filtering only; any <span><strong class="command">key_id</strong></span> 980 elements of the <span><strong class="command">address_match_list</strong></span> 981 are ignored. 982 </p> 983<p> 984 A <span><strong class="command">unix</strong></span> control channel is a UNIX domain 985 socket listening at the specified path in the file system. 986 Access to the socket is specified by the <span><strong class="command">perm</strong></span>, 987 <span><strong class="command">owner</strong></span> and <span><strong class="command">group</strong></span> clauses. 988 Note on some platforms (SunOS and Solaris) the permissions 989 (<span><strong class="command">perm</strong></span>) are applied to the parent directory 990 as the permissions on the socket itself are ignored. 991 </p> 992<p> 993 The primary authorization mechanism of the command 994 channel is the <span><strong class="command">key_list</strong></span>, which 995 contains a list of <span><strong class="command">key_id</strong></span>s. 996 Each <span><strong class="command">key_id</strong></span> in the <span><strong class="command">key_list</strong></span> 997 is authorized to execute commands over the control channel. 998 See <a href="Bv9ARM.ch03.html#rndc">Remote Name Daemon Control application</a> in <a href="Bv9ARM.ch03.html#admin_tools" title="Administrative Tools">the section called “Administrative Tools”</a>) 999 for information about configuring keys in <span><strong class="command">rndc</strong></span>. 1000 </p> 1001<p> 1002 If no <span><strong class="command">controls</strong></span> statement is present, 1003 <span><strong class="command">named</strong></span> will set up a default 1004 control channel listening on the loopback address 127.0.0.1 1005 and its IPv6 counterpart ::1. 1006 In this case, and also when the <span><strong class="command">controls</strong></span> statement 1007 is present but does not have a <span><strong class="command">keys</strong></span> clause, 1008 <span><strong class="command">named</strong></span> will attempt to load the command channel key 1009 from the file <code class="filename">rndc.key</code> in 1010 <code class="filename">/etc</code> (or whatever <code class="varname">sysconfdir</code> 1011 was specified as when <acronym class="acronym">BIND</acronym> was built). 1012 To create a <code class="filename">rndc.key</code> file, run 1013 <strong class="userinput"><code>rndc-confgen -a</code></strong>. 1014 </p> 1015<p> 1016 The <code class="filename">rndc.key</code> feature was created to 1017 ease the transition of systems from <acronym class="acronym">BIND</acronym> 8, 1018 which did not have digital signatures on its command channel 1019 messages and thus did not have a <span><strong class="command">keys</strong></span> clause. 1020 1021 It makes it possible to use an existing <acronym class="acronym">BIND</acronym> 8 1022 configuration file in <acronym class="acronym">BIND</acronym> 9 unchanged, 1023 and still have <span><strong class="command">rndc</strong></span> work the same way 1024 <span><strong class="command">ndc</strong></span> worked in BIND 8, simply by executing the 1025 command <strong class="userinput"><code>rndc-confgen -a</code></strong> after BIND 9 is 1026 installed. 1027 </p> 1028<p> 1029 Since the <code class="filename">rndc.key</code> feature 1030 is only intended to allow the backward-compatible usage of 1031 <acronym class="acronym">BIND</acronym> 8 configuration files, this 1032 feature does not 1033 have a high degree of configurability. You cannot easily change 1034 the key name or the size of the secret, so you should make a 1035 <code class="filename">rndc.conf</code> with your own key if you 1036 wish to change 1037 those things. The <code class="filename">rndc.key</code> file 1038 also has its 1039 permissions set such that only the owner of the file (the user that 1040 <span><strong class="command">named</strong></span> is running as) can access it. 1041 If you 1042 desire greater flexibility in allowing other users to access 1043 <span><strong class="command">rndc</strong></span> commands, then you need to create 1044 a 1045 <code class="filename">rndc.conf</code> file and make it group 1046 readable by a group 1047 that contains the users who should have access. 1048 </p> 1049<p> 1050 To disable the command channel, use an empty 1051 <span><strong class="command">controls</strong></span> statement: 1052 <span><strong class="command">controls { };</strong></span>. 1053 </p> 1054</div> 1055<div class="sect2" lang="en"> 1056<div class="titlepage"><div><div><h3 class="title"> 1057<a name="id2575467"></a><span><strong class="command">include</strong></span> Statement Grammar</h3></div></div></div> 1058<pre class="programlisting"><span><strong class="command">include</strong></span> <em class="replaceable"><code>filename</code></em>;</pre> 1059</div> 1060<div class="sect2" lang="en"> 1061<div class="titlepage"><div><div><h3 class="title"> 1062<a name="id2575484"></a><span><strong class="command">include</strong></span> Statement Definition and 1063 Usage</h3></div></div></div> 1064<p> 1065 The <span><strong class="command">include</strong></span> statement inserts the 1066 specified file at the point where the <span><strong class="command">include</strong></span> 1067 statement is encountered. The <span><strong class="command">include</strong></span> 1068 statement facilitates the administration of configuration 1069 files 1070 by permitting the reading or writing of some things but not 1071 others. For example, the statement could include private keys 1072 that are readable only by the name server. 1073 </p> 1074</div> 1075<div class="sect2" lang="en"> 1076<div class="titlepage"><div><div><h3 class="title"> 1077<a name="id2575576"></a><span><strong class="command">key</strong></span> Statement Grammar</h3></div></div></div> 1078<pre class="programlisting"><span><strong class="command">key</strong></span> <em class="replaceable"><code>key_id</code></em> { 1079 algorithm <em class="replaceable"><code>string</code></em>; 1080 secret <em class="replaceable"><code>string</code></em>; 1081}; 1082</pre> 1083</div> 1084<div class="sect2" lang="en"> 1085<div class="titlepage"><div><div><h3 class="title"> 1086<a name="id2575600"></a><span><strong class="command">key</strong></span> Statement Definition and Usage</h3></div></div></div> 1087<p> 1088 The <span><strong class="command">key</strong></span> statement defines a shared 1089 secret key for use with TSIG (see <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called “TSIG”</a>) 1090 or the command channel 1091 (see <a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and 1092 Usage">the section called “<span><strong class="command">controls</strong></span> Statement Definition and 1093 Usage”</a>). 1094 </p> 1095<p> 1096 The <span><strong class="command">key</strong></span> statement can occur at the 1097 top level 1098 of the configuration file or inside a <span><strong class="command">view</strong></span> 1099 statement. Keys defined in top-level <span><strong class="command">key</strong></span> 1100 statements can be used in all views. Keys intended for use in 1101 a <span><strong class="command">controls</strong></span> statement 1102 (see <a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and 1103 Usage">the section called “<span><strong class="command">controls</strong></span> Statement Definition and 1104 Usage”</a>) 1105 must be defined at the top level. 1106 </p> 1107<p> 1108 The <em class="replaceable"><code>key_id</code></em>, also known as the 1109 key name, is a domain name uniquely identifying the key. It can 1110 be used in a <span><strong class="command">server</strong></span> 1111 statement to cause requests sent to that 1112 server to be signed with this key, or in address match lists to 1113 verify that incoming requests have been signed with a key 1114 matching this name, algorithm, and secret. 1115 </p> 1116<p> 1117 The <em class="replaceable"><code>algorithm_id</code></em> is a string 1118 that specifies a security/authentication algorithm. Named 1119 supports <code class="literal">hmac-md5</code>, 1120 <code class="literal">hmac-sha1</code>, <code class="literal">hmac-sha224</code>, 1121 <code class="literal">hmac-sha256</code>, <code class="literal">hmac-sha384</code> 1122 and <code class="literal">hmac-sha512</code> TSIG authentication. 1123 Truncated hashes are supported by appending the minimum 1124 number of required bits preceded by a dash, e.g. 1125 <code class="literal">hmac-sha1-80</code>. The 1126 <em class="replaceable"><code>secret_string</code></em> is the secret 1127 to be used by the algorithm, and is treated as a base-64 1128 encoded string. 1129 </p> 1130</div> 1131<div class="sect2" lang="en"> 1132<div class="titlepage"><div><div><h3 class="title"> 1133<a name="id2575758"></a><span><strong class="command">logging</strong></span> Statement Grammar</h3></div></div></div> 1134<pre class="programlisting"><span><strong class="command">logging</strong></span> { 1135 [ <span><strong class="command">channel</strong></span> <em class="replaceable"><code>channel_name</code></em> { 1136 ( <span><strong class="command">file</strong></span> <em class="replaceable"><code>path_name</code></em> 1137 [ <span><strong class="command">versions</strong></span> ( <em class="replaceable"><code>number</code></em> | <span><strong class="command">unlimited</strong></span> ) ] 1138 [ <span><strong class="command">size</strong></span> <em class="replaceable"><code>size spec</code></em> ] 1139 | <span><strong class="command">syslog</strong></span> <em class="replaceable"><code>syslog_facility</code></em> 1140 | <span><strong class="command">stderr</strong></span> 1141 | <span><strong class="command">null</strong></span> ); 1142 [ <span><strong class="command">severity</strong></span> (<code class="option">critical</code> | <code class="option">error</code> | <code class="option">warning</code> | <code class="option">notice</code> | 1143 <code class="option">info</code> | <code class="option">debug</code> [ <em class="replaceable"><code>level</code></em> ] | <code class="option">dynamic</code> ); ] 1144 [ <span><strong class="command">print-category</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ] 1145 [ <span><strong class="command">print-severity</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ] 1146 [ <span><strong class="command">print-time</strong></span> <code class="option">yes</code> or <code class="option">no</code>; ] 1147 }; ] 1148 [ <span><strong class="command">category</strong></span> <em class="replaceable"><code>category_name</code></em> { 1149 <em class="replaceable"><code>channel_name</code></em> ; [ <em class="replaceable"><code>channel_name</code></em> ; ... ] 1150 }; ] 1151 ... 1152}; 1153</pre> 1154</div> 1155<div class="sect2" lang="en"> 1156<div class="titlepage"><div><div><h3 class="title"> 1157<a name="id2575884"></a><span><strong class="command">logging</strong></span> Statement Definition and 1158 Usage</h3></div></div></div> 1159<p> 1160 The <span><strong class="command">logging</strong></span> statement configures a 1161 wide 1162 variety of logging options for the name server. Its <span><strong class="command">channel</strong></span> phrase 1163 associates output methods, format options and severity levels with 1164 a name that can then be used with the <span><strong class="command">category</strong></span> phrase 1165 to select how various classes of messages are logged. 1166 </p> 1167<p> 1168 Only one <span><strong class="command">logging</strong></span> statement is used to 1169 define 1170 as many channels and categories as are wanted. If there is no <span><strong class="command">logging</strong></span> statement, 1171 the logging configuration will be: 1172 </p> 1173<pre class="programlisting">logging { 1174 category default { default_syslog; default_debug; }; 1175 category unmatched { null; }; 1176}; 1177</pre> 1178<p> 1179 In <acronym class="acronym">BIND</acronym> 9, the logging configuration 1180 is only established when 1181 the entire configuration file has been parsed. In <acronym class="acronym">BIND</acronym> 8, it was 1182 established as soon as the <span><strong class="command">logging</strong></span> 1183 statement 1184 was parsed. When the server is starting up, all logging messages 1185 regarding syntax errors in the configuration file go to the default 1186 channels, or to standard error if the "<code class="option">-g</code>" option 1187 was specified. 1188 </p> 1189<div class="sect3" lang="en"> 1190<div class="titlepage"><div><div><h4 class="title"> 1191<a name="id2576005"></a>The <span><strong class="command">channel</strong></span> Phrase</h4></div></div></div> 1192<p> 1193 All log output goes to one or more <span class="emphasis"><em>channels</em></span>; 1194 you can make as many of them as you want. 1195 </p> 1196<p> 1197 Every channel definition must include a destination clause that 1198 says whether messages selected for the channel go to a file, to a 1199 particular syslog facility, to the standard error stream, or are 1200 discarded. It can optionally also limit the message severity level 1201 that will be accepted by the channel (the default is 1202 <span><strong class="command">info</strong></span>), and whether to include a 1203 <span><strong class="command">named</strong></span>-generated time stamp, the 1204 category name 1205 and/or severity level (the default is not to include any). 1206 </p> 1207<p> 1208 The <span><strong class="command">null</strong></span> destination clause 1209 causes all messages sent to the channel to be discarded; 1210 in that case, other options for the channel are meaningless. 1211 </p> 1212<p> 1213 The <span><strong class="command">file</strong></span> destination clause directs 1214 the channel 1215 to a disk file. It can include limitations 1216 both on how large the file is allowed to become, and how many 1217 versions 1218 of the file will be saved each time the file is opened. 1219 </p> 1220<p> 1221 If you use the <span><strong class="command">versions</strong></span> log file 1222 option, then 1223 <span><strong class="command">named</strong></span> will retain that many backup 1224 versions of the file by 1225 renaming them when opening. For example, if you choose to keep 1226 three old versions 1227 of the file <code class="filename">lamers.log</code>, then just 1228 before it is opened 1229 <code class="filename">lamers.log.1</code> is renamed to 1230 <code class="filename">lamers.log.2</code>, <code class="filename">lamers.log.0</code> is renamed 1231 to <code class="filename">lamers.log.1</code>, and <code class="filename">lamers.log</code> is 1232 renamed to <code class="filename">lamers.log.0</code>. 1233 You can say <span><strong class="command">versions unlimited</strong></span> to 1234 not limit 1235 the number of versions. 1236 If a <span><strong class="command">size</strong></span> option is associated with 1237 the log file, 1238 then renaming is only done when the file being opened exceeds the 1239 indicated size. No backup versions are kept by default; any 1240 existing 1241 log file is simply appended. 1242 </p> 1243<p> 1244 The <span><strong class="command">size</strong></span> option for files is used 1245 to limit log 1246 growth. If the file ever exceeds the size, then <span><strong class="command">named</strong></span> will 1247 stop writing to the file unless it has a <span><strong class="command">versions</strong></span> option 1248 associated with it. If backup versions are kept, the files are 1249 rolled as 1250 described above and a new one begun. If there is no 1251 <span><strong class="command">versions</strong></span> option, no more data will 1252 be written to the log 1253 until some out-of-band mechanism removes or truncates the log to 1254 less than the 1255 maximum size. The default behavior is not to limit the size of 1256 the 1257 file. 1258 </p> 1259<p> 1260 Example usage of the <span><strong class="command">size</strong></span> and 1261 <span><strong class="command">versions</strong></span> options: 1262 </p> 1263<pre class="programlisting">channel an_example_channel { 1264 file "example.log" versions 3 size 20m; 1265 print-time yes; 1266 print-category yes; 1267}; 1268</pre> 1269<p> 1270 The <span><strong class="command">syslog</strong></span> destination clause 1271 directs the 1272 channel to the system log. Its argument is a 1273 syslog facility as described in the <span><strong class="command">syslog</strong></span> man 1274 page. Known facilities are <span><strong class="command">kern</strong></span>, <span><strong class="command">user</strong></span>, 1275 <span><strong class="command">mail</strong></span>, <span><strong class="command">daemon</strong></span>, <span><strong class="command">auth</strong></span>, 1276 <span><strong class="command">syslog</strong></span>, <span><strong class="command">lpr</strong></span>, <span><strong class="command">news</strong></span>, 1277 <span><strong class="command">uucp</strong></span>, <span><strong class="command">cron</strong></span>, <span><strong class="command">authpriv</strong></span>, 1278 <span><strong class="command">ftp</strong></span>, <span><strong class="command">local0</strong></span>, <span><strong class="command">local1</strong></span>, 1279 <span><strong class="command">local2</strong></span>, <span><strong class="command">local3</strong></span>, <span><strong class="command">local4</strong></span>, 1280 <span><strong class="command">local5</strong></span>, <span><strong class="command">local6</strong></span> and 1281 <span><strong class="command">local7</strong></span>, however not all facilities 1282 are supported on 1283 all operating systems. 1284 How <span><strong class="command">syslog</strong></span> will handle messages 1285 sent to 1286 this facility is described in the <span><strong class="command">syslog.conf</strong></span> man 1287 page. If you have a system which uses a very old version of <span><strong class="command">syslog</strong></span> that 1288 only uses two arguments to the <span><strong class="command">openlog()</strong></span> function, 1289 then this clause is silently ignored. 1290 </p> 1291<p> 1292 The <span><strong class="command">severity</strong></span> clause works like <span><strong class="command">syslog</strong></span>'s 1293 "priorities", except that they can also be used if you are writing 1294 straight to a file rather than using <span><strong class="command">syslog</strong></span>. 1295 Messages which are not at least of the severity level given will 1296 not be selected for the channel; messages of higher severity 1297 levels 1298 will be accepted. 1299 </p> 1300<p> 1301 If you are using <span><strong class="command">syslog</strong></span>, then the <span><strong class="command">syslog.conf</strong></span> priorities 1302 will also determine what eventually passes through. For example, 1303 defining a channel facility and severity as <span><strong class="command">daemon</strong></span> and <span><strong class="command">debug</strong></span> but 1304 only logging <span><strong class="command">daemon.warning</strong></span> via <span><strong class="command">syslog.conf</strong></span> will 1305 cause messages of severity <span><strong class="command">info</strong></span> and 1306 <span><strong class="command">notice</strong></span> to 1307 be dropped. If the situation were reversed, with <span><strong class="command">named</strong></span> writing 1308 messages of only <span><strong class="command">warning</strong></span> or higher, 1309 then <span><strong class="command">syslogd</strong></span> would 1310 print all messages it received from the channel. 1311 </p> 1312<p> 1313 The <span><strong class="command">stderr</strong></span> destination clause 1314 directs the 1315 channel to the server's standard error stream. This is intended 1316 for 1317 use when the server is running as a foreground process, for 1318 example 1319 when debugging a configuration. 1320 </p> 1321<p> 1322 The server can supply extensive debugging information when 1323 it is in debugging mode. If the server's global debug level is 1324 greater 1325 than zero, then debugging mode will be active. The global debug 1326 level is set either by starting the <span><strong class="command">named</strong></span> server 1327 with the <code class="option">-d</code> flag followed by a positive integer, 1328 or by running <span><strong class="command">rndc trace</strong></span>. 1329 The global debug level 1330 can be set to zero, and debugging mode turned off, by running <span><strong class="command">rndc 1331notrace</strong></span>. All debugging messages in the server have a debug 1332 level, and higher debug levels give more detailed output. Channels 1333 that specify a specific debug severity, for example: 1334 </p> 1335<pre class="programlisting">channel specific_debug_level { 1336 file "foo"; 1337 severity debug 3; 1338}; 1339</pre> 1340<p> 1341 will get debugging output of level 3 or less any time the 1342 server is in debugging mode, regardless of the global debugging 1343 level. Channels with <span><strong class="command">dynamic</strong></span> 1344 severity use the 1345 server's global debug level to determine what messages to print. 1346 </p> 1347<p> 1348 If <span><strong class="command">print-time</strong></span> has been turned on, 1349 then 1350 the date and time will be logged. <span><strong class="command">print-time</strong></span> may 1351 be specified for a <span><strong class="command">syslog</strong></span> channel, 1352 but is usually 1353 pointless since <span><strong class="command">syslog</strong></span> also logs 1354 the date and 1355 time. If <span><strong class="command">print-category</strong></span> is 1356 requested, then the 1357 category of the message will be logged as well. Finally, if <span><strong class="command">print-severity</strong></span> is 1358 on, then the severity level of the message will be logged. The <span><strong class="command">print-</strong></span> options may 1359 be used in any combination, and will always be printed in the 1360 following 1361 order: time, category, severity. Here is an example where all 1362 three <span><strong class="command">print-</strong></span> options 1363 are on: 1364 </p> 1365<p> 1366 <code class="computeroutput">28-Feb-2000 15:05:32.863 general: notice: running</code> 1367 </p> 1368<p> 1369 There are four predefined channels that are used for 1370 <span><strong class="command">named</strong></span>'s default logging as follows. 1371 How they are 1372 used is described in <a href="Bv9ARM.ch06.html#the_category_phrase" title="The category Phrase">the section called “The <span><strong class="command">category</strong></span> Phrase”</a>. 1373 </p> 1374<pre class="programlisting">channel default_syslog { 1375 // send to syslog's daemon facility 1376 syslog daemon; 1377 // only send priority info and higher 1378 severity info; 1379 1380channel default_debug { 1381 // write to named.run in the working directory 1382 // Note: stderr is used instead of "named.run" if 1383 // the server is started with the '-f' option. 1384 file "named.run"; 1385 // log at the server's current debug level 1386 severity dynamic; 1387}; 1388 1389channel default_stderr { 1390 // writes to stderr 1391 stderr; 1392 // only send priority info and higher 1393 severity info; 1394}; 1395 1396channel null { 1397 // toss anything sent to this channel 1398 null; 1399}; 1400</pre> 1401<p> 1402 The <span><strong class="command">default_debug</strong></span> channel has the 1403 special 1404 property that it only produces output when the server's debug 1405 level is 1406 nonzero. It normally writes to a file called <code class="filename">named.run</code> 1407 in the server's working directory. 1408 </p> 1409<p> 1410 For security reasons, when the "<code class="option">-u</code>" 1411 command line option is used, the <code class="filename">named.run</code> file 1412 is created only after <span><strong class="command">named</strong></span> has 1413 changed to the 1414 new UID, and any debug output generated while <span><strong class="command">named</strong></span> is 1415 starting up and still running as root is discarded. If you need 1416 to capture this output, you must run the server with the "<code class="option">-g</code>" 1417 option and redirect standard error to a file. 1418 </p> 1419<p> 1420 Once a channel is defined, it cannot be redefined. Thus you 1421 cannot alter the built-in channels directly, but you can modify 1422 the default logging by pointing categories at channels you have 1423 defined. 1424 </p> 1425</div> 1426<div class="sect3" lang="en"> 1427<div class="titlepage"><div><div><h4 class="title"> 1428<a name="the_category_phrase"></a>The <span><strong class="command">category</strong></span> Phrase</h4></div></div></div> 1429<p> 1430 There are many categories, so you can send the logs you want 1431 to see wherever you want, without seeing logs you don't want. If 1432 you don't specify a list of channels for a category, then log 1433 messages 1434 in that category will be sent to the <span><strong class="command">default</strong></span> category 1435 instead. If you don't specify a default category, the following 1436 "default default" is used: 1437 </p> 1438<pre class="programlisting">category default { default_syslog; default_debug; }; 1439</pre> 1440<p> 1441 As an example, let's say you want to log security events to 1442 a file, but you also want keep the default logging behavior. You'd 1443 specify the following: 1444 </p> 1445<pre class="programlisting">channel my_security_channel { 1446 file "my_security_file"; 1447 severity info; 1448}; 1449category security { 1450 my_security_channel; 1451 default_syslog; 1452 default_debug; 1453};</pre> 1454<p> 1455 To discard all messages in a category, specify the <span><strong class="command">null</strong></span> channel: 1456 </p> 1457<pre class="programlisting">category xfer-out { null; }; 1458category notify { null; }; 1459</pre> 1460<p> 1461 Following are the available categories and brief descriptions 1462 of the types of log information they contain. More 1463 categories may be added in future <acronym class="acronym">BIND</acronym> releases. 1464 </p> 1465<div class="informaltable"><table border="1"> 1466<colgroup> 1467<col> 1468<col> 1469</colgroup> 1470<tbody> 1471<tr> 1472<td> 1473 <p><span><strong class="command">default</strong></span></p> 1474 </td> 1475<td> 1476 <p> 1477 The default category defines the logging 1478 options for those categories where no specific 1479 configuration has been 1480 defined. 1481 </p> 1482 </td> 1483</tr> 1484<tr> 1485<td> 1486 <p><span><strong class="command">general</strong></span></p> 1487 </td> 1488<td> 1489 <p> 1490 The catch-all. Many things still aren't 1491 classified into categories, and they all end up here. 1492 </p> 1493 </td> 1494</tr> 1495<tr> 1496<td> 1497 <p><span><strong class="command">database</strong></span></p> 1498 </td> 1499<td> 1500 <p> 1501 Messages relating to the databases used 1502 internally by the name server to store zone and cache 1503 data. 1504 </p> 1505 </td> 1506</tr> 1507<tr> 1508<td> 1509 <p><span><strong class="command">security</strong></span></p> 1510 </td> 1511<td> 1512 <p> 1513 Approval and denial of requests. 1514 </p> 1515 </td> 1516</tr> 1517<tr> 1518<td> 1519 <p><span><strong class="command">config</strong></span></p> 1520 </td> 1521<td> 1522 <p> 1523 Configuration file parsing and processing. 1524 </p> 1525 </td> 1526</tr> 1527<tr> 1528<td> 1529 <p><span><strong class="command">resolver</strong></span></p> 1530 </td> 1531<td> 1532 <p> 1533 DNS resolution, such as the recursive 1534 lookups performed on behalf of clients by a caching name 1535 server. 1536 </p> 1537 </td> 1538</tr> 1539<tr> 1540<td> 1541 <p><span><strong class="command">xfer-in</strong></span></p> 1542 </td> 1543<td> 1544 <p> 1545 Zone transfers the server is receiving. 1546 </p> 1547 </td> 1548</tr> 1549<tr> 1550<td> 1551 <p><span><strong class="command">xfer-out</strong></span></p> 1552 </td> 1553<td> 1554 <p> 1555 Zone transfers the server is sending. 1556 </p> 1557 </td> 1558</tr> 1559<tr> 1560<td> 1561 <p><span><strong class="command">notify</strong></span></p> 1562 </td> 1563<td> 1564 <p> 1565 The NOTIFY protocol. 1566 </p> 1567 </td> 1568</tr> 1569<tr> 1570<td> 1571 <p><span><strong class="command">client</strong></span></p> 1572 </td> 1573<td> 1574 <p> 1575 Processing of client requests. 1576 </p> 1577 </td> 1578</tr> 1579<tr> 1580<td> 1581 <p><span><strong class="command">unmatched</strong></span></p> 1582 </td> 1583<td> 1584 <p> 1585 Messages that <span><strong class="command">named</strong></span> was unable to determine the 1586 class of or for which there was no matching <span><strong class="command">view</strong></span>. 1587 A one line summary is also logged to the <span><strong class="command">client</strong></span> category. 1588 This category is best sent to a file or stderr, by 1589 default it is sent to 1590 the <span><strong class="command">null</strong></span> channel. 1591 </p> 1592 </td> 1593</tr> 1594<tr> 1595<td> 1596 <p><span><strong class="command">network</strong></span></p> 1597 </td> 1598<td> 1599 <p> 1600 Network operations. 1601 </p> 1602 </td> 1603</tr> 1604<tr> 1605<td> 1606 <p><span><strong class="command">update</strong></span></p> 1607 </td> 1608<td> 1609 <p> 1610 Dynamic updates. 1611 </p> 1612 </td> 1613</tr> 1614<tr> 1615<td> 1616 <p><span><strong class="command">update-security</strong></span></p> 1617 </td> 1618<td> 1619 <p> 1620 Approval and denial of update requests. 1621 </p> 1622 </td> 1623</tr> 1624<tr> 1625<td> 1626 <p><span><strong class="command">queries</strong></span></p> 1627 </td> 1628<td> 1629 <p> 1630 Specify where queries should be logged to. 1631 </p> 1632 <p> 1633 At startup, specifying the category <span><strong class="command">queries</strong></span> will also 1634 enable query logging unless <span><strong class="command">querylog</strong></span> option has been 1635 specified. 1636 </p> 1637 1638 <p> 1639 The query log entry reports the client's IP 1640 address and port number, and the query name, 1641 class and type. Next it reports whether the 1642 Recursion Desired flag was set (+ if set, - 1643 if not set), if the query was signed (S), 1644 EDNS was in use (E), if TCP was used (T), if 1645 DO (DNSSEC Ok) was set (D), or if CD (Checking 1646 Disabled) was set (C). After this the 1647 destination address the query was sent to is 1648 reported. 1649 </p> 1650 1651 <p> 1652 <code class="computeroutput">client 127.0.0.1#62536: query: www.example.com IN AAAA +SE</code> 1653 </p> 1654 <p> 1655 <code class="computeroutput">client ::1#62537: query: www.example.net IN AAAA -SE</code> 1656 </p> 1657 </td> 1658</tr> 1659<tr> 1660<td> 1661 <p><span><strong class="command">query-errors</strong></span></p> 1662 </td> 1663<td> 1664 <p> 1665 Information about queries that resulted in some 1666 failure. 1667 </p> 1668 </td> 1669</tr> 1670<tr> 1671<td> 1672 <p><span><strong class="command">dispatch</strong></span></p> 1673 </td> 1674<td> 1675 <p> 1676 Dispatching of incoming packets to the 1677 server modules where they are to be processed. 1678 </p> 1679 </td> 1680</tr> 1681<tr> 1682<td> 1683 <p><span><strong class="command">dnssec</strong></span></p> 1684 </td> 1685<td> 1686 <p> 1687 DNSSEC and TSIG protocol processing. 1688 </p> 1689 </td> 1690</tr> 1691<tr> 1692<td> 1693 <p><span><strong class="command">lame-servers</strong></span></p> 1694 </td> 1695<td> 1696 <p> 1697 Lame servers. These are misconfigurations 1698 in remote servers, discovered by BIND 9 when trying to 1699 query those servers during resolution. 1700 </p> 1701 </td> 1702</tr> 1703<tr> 1704<td> 1705 <p><span><strong class="command">delegation-only</strong></span></p> 1706 </td> 1707<td> 1708 <p> 1709 Delegation only. Logs queries that have been 1710 forced to NXDOMAIN as the result of a 1711 delegation-only zone or a 1712 <span><strong class="command">delegation-only</strong></span> in a hint 1713 or stub zone declaration. 1714 </p> 1715 </td> 1716</tr> 1717<tr> 1718<td> 1719 <p><span><strong class="command">edns-disabled</strong></span></p> 1720 </td> 1721<td> 1722 <p> 1723 Log queries that have been forced to use plain 1724 DNS due to timeouts. This is often due to 1725 the remote servers not being RFC 1034 compliant 1726 (not always returning FORMERR or similar to 1727 EDNS queries and other extensions to the DNS 1728 when they are not understood). In other words, this is 1729 targeted at servers that fail to respond to 1730 DNS queries that they don't understand. 1731 </p> 1732 <p> 1733 Note: the log message can also be due to 1734 packet loss. Before reporting servers for 1735 non-RFC 1034 compliance they should be re-tested 1736 to determine the nature of the non-compliance. 1737 This testing should prevent or reduce the 1738 number of false-positive reports. 1739 </p> 1740 <p> 1741 Note: eventually <span><strong class="command">named</strong></span> will have to stop 1742 treating such timeouts as due to RFC 1034 non 1743 compliance and start treating it as plain 1744 packet loss. Falsely classifying packet 1745 loss as due to RFC 1034 non compliance impacts 1746 on DNSSEC validation which requires EDNS for 1747 the DNSSEC records to be returned. 1748 </p> 1749 </td> 1750</tr> 1751<tr> 1752<td> 1753 <p><span><strong class="command">RPZ</strong></span></p> 1754 </td> 1755<td> 1756 <p> 1757 Information about errors in response policy zone files, 1758 rewritten responses, and at the highest 1759 <span><strong class="command">debug</strong></span> levels, mere rewriting 1760 attempts. 1761 </p> 1762 </td> 1763</tr> 1764</tbody> 1765</table></div> 1766</div> 1767<div class="sect3" lang="en"> 1768<div class="titlepage"><div><div><h4 class="title"> 1769<a name="id2577322"></a>The <span><strong class="command">query-errors</strong></span> Category</h4></div></div></div> 1770<p> 1771 The <span><strong class="command">query-errors</strong></span> category is 1772 specifically intended for debugging purposes: To identify 1773 why and how specific queries result in responses which 1774 indicate an error. 1775 Messages of this category are therefore only logged 1776 with <span><strong class="command">debug</strong></span> levels. 1777 </p> 1778<p> 1779 At the debug levels of 1 or higher, each response with the 1780 rcode of SERVFAIL is logged as follows: 1781 </p> 1782<p> 1783 <code class="computeroutput">client 127.0.0.1#61502: query failed (SERVFAIL) for www.example.com/IN/AAAA at query.c:3880</code> 1784 </p> 1785<p> 1786 This means an error resulting in SERVFAIL was 1787 detected at line 3880 of source file 1788 <code class="filename">query.c</code>. 1789 Log messages of this level will particularly 1790 help identify the cause of SERVFAIL for an 1791 authoritative server. 1792 </p> 1793<p> 1794 At the debug levels of 2 or higher, detailed context 1795 information of recursive resolutions that resulted in 1796 SERVFAIL is logged. 1797 The log message will look like as follows: 1798 </p> 1799<p> 1800 1801 </p> 1802<pre class="programlisting"> 1803fetch completed at resolver.c:2970 for www.example.com/A 1804in 30.000183: timed out/success [domain:example.com, 1805referral:2,restart:7,qrysent:8,timeout:5,lame:0,neterr:0, 1806badresp:1,adberr:0,findfail:0,valfail:0] 1807 </pre> 1808<p> 1809 </p> 1810<p> 1811 The first part before the colon shows that a recursive 1812 resolution for AAAA records of www.example.com completed 1813 in 30.000183 seconds and the final result that led to the 1814 SERVFAIL was determined at line 2970 of source file 1815 <code class="filename">resolver.c</code>. 1816 </p> 1817<p> 1818 The following part shows the detected final result and the 1819 latest result of DNSSEC validation. 1820 The latter is always success when no validation attempt 1821 is made. 1822 In this example, this query resulted in SERVFAIL probably 1823 because all name servers are down or unreachable, leading 1824 to a timeout in 30 seconds. 1825 DNSSEC validation was probably not attempted. 1826 </p> 1827<p> 1828 The last part enclosed in square brackets shows statistics 1829 information collected for this particular resolution 1830 attempt. 1831 The <code class="varname">domain</code> field shows the deepest zone 1832 that the resolver reached; 1833 it is the zone where the error was finally detected. 1834 The meaning of the other fields is summarized in the 1835 following table. 1836 </p> 1837<div class="informaltable"><table border="1"> 1838<colgroup> 1839<col> 1840<col> 1841</colgroup> 1842<tbody> 1843<tr> 1844<td> 1845 <p><code class="varname">referral</code></p> 1846 </td> 1847<td> 1848 <p> 1849 The number of referrals the resolver received 1850 throughout the resolution process. 1851 In the above example this is 2, which are most 1852 likely com and example.com. 1853 </p> 1854 </td> 1855</tr> 1856<tr> 1857<td> 1858 <p><code class="varname">restart</code></p> 1859 </td> 1860<td> 1861 <p> 1862 The number of cycles that the resolver tried 1863 remote servers at the <code class="varname">domain</code> 1864 zone. 1865 In each cycle the resolver sends one query 1866 (possibly resending it, depending on the response) 1867 to each known name server of 1868 the <code class="varname">domain</code> zone. 1869 </p> 1870 </td> 1871</tr> 1872<tr> 1873<td> 1874 <p><code class="varname">qrysent</code></p> 1875 </td> 1876<td> 1877 <p> 1878 The number of queries the resolver sent at the 1879 <code class="varname">domain</code> zone. 1880 </p> 1881 </td> 1882</tr> 1883<tr> 1884<td> 1885 <p><code class="varname">timeout</code></p> 1886 </td> 1887<td> 1888 <p> 1889 The number of timeouts since the resolver 1890 received the last response. 1891 </p> 1892 </td> 1893</tr> 1894<tr> 1895<td> 1896 <p><code class="varname">lame</code></p> 1897 </td> 1898<td> 1899 <p> 1900 The number of lame servers the resolver detected 1901 at the <code class="varname">domain</code> zone. 1902 A server is detected to be lame either by an 1903 invalid response or as a result of lookup in 1904 BIND9's address database (ADB), where lame 1905 servers are cached. 1906 </p> 1907 </td> 1908</tr> 1909<tr> 1910<td> 1911 <p><code class="varname">neterr</code></p> 1912 </td> 1913<td> 1914 <p> 1915 The number of erroneous results that the 1916 resolver encountered in sending queries 1917 at the <code class="varname">domain</code> zone. 1918 One common case is the remote server is 1919 unreachable and the resolver receives an ICMP 1920 unreachable error message. 1921 </p> 1922 </td> 1923</tr> 1924<tr> 1925<td> 1926 <p><code class="varname">badresp</code></p> 1927 </td> 1928<td> 1929 <p> 1930 The number of unexpected responses (other than 1931 <code class="varname">lame</code>) to queries sent by the 1932 resolver at the <code class="varname">domain</code> zone. 1933 </p> 1934 </td> 1935</tr> 1936<tr> 1937<td> 1938 <p><code class="varname">adberr</code></p> 1939 </td> 1940<td> 1941 <p> 1942 Failures in finding remote server addresses 1943 of the <code class="varname">domain</code> zone in the ADB. 1944 One common case of this is that the remote 1945 server's name does not have any address records. 1946 </p> 1947 </td> 1948</tr> 1949<tr> 1950<td> 1951 <p><code class="varname">findfail</code></p> 1952 </td> 1953<td> 1954 <p> 1955 Failures of resolving remote server addresses. 1956 This is a total number of failures throughout 1957 the resolution process. 1958 </p> 1959 </td> 1960</tr> 1961<tr> 1962<td> 1963 <p><code class="varname">valfail</code></p> 1964 </td> 1965<td> 1966 <p> 1967 Failures of DNSSEC validation. 1968 Validation failures are counted throughout 1969 the resolution process (not limited to 1970 the <code class="varname">domain</code> zone), but should 1971 only happen in <code class="varname">domain</code>. 1972 </p> 1973 </td> 1974</tr> 1975</tbody> 1976</table></div> 1977<p> 1978 At the debug levels of 3 or higher, the same messages 1979 as those at the debug 1 level are logged for other errors 1980 than SERVFAIL. 1981 Note that negative responses such as NXDOMAIN are not 1982 regarded as errors here. 1983 </p> 1984<p> 1985 At the debug levels of 4 or higher, the same messages 1986 as those at the debug 2 level are logged for other errors 1987 than SERVFAIL. 1988 Unlike the above case of level 3, messages are logged for 1989 negative responses. 1990 This is because any unexpected results can be difficult to 1991 debug in the recursion case. 1992 </p> 1993</div> 1994</div> 1995<div class="sect2" lang="en"> 1996<div class="titlepage"><div><div><h3 class="title"> 1997<a name="id2577910"></a><span><strong class="command">lwres</strong></span> Statement Grammar</h3></div></div></div> 1998<p> 1999 This is the grammar of the <span><strong class="command">lwres</strong></span> 2000 statement in the <code class="filename">named.conf</code> file: 2001 </p> 2002<pre class="programlisting"><span><strong class="command">lwres</strong></span> { 2003 [<span class="optional"> listen-on { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; 2004 [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] 2005 [<span class="optional"> view <em class="replaceable"><code>view_name</code></em>; </span>] 2006 [<span class="optional"> search { <em class="replaceable"><code>domain_name</code></em> ; [<span class="optional"> <em class="replaceable"><code>domain_name</code></em> ; ... </span>] }; </span>] 2007 [<span class="optional"> ndots <em class="replaceable"><code>number</code></em>; </span>] 2008}; 2009</pre> 2010</div> 2011<div class="sect2" lang="en"> 2012<div class="titlepage"><div><div><h3 class="title"> 2013<a name="id2577984"></a><span><strong class="command">lwres</strong></span> Statement Definition and Usage</h3></div></div></div> 2014<p> 2015 The <span><strong class="command">lwres</strong></span> statement configures the 2016 name 2017 server to also act as a lightweight resolver server. (See 2018 <a href="Bv9ARM.ch05.html#lwresd" title="Running a Resolver Daemon">the section called “Running a Resolver Daemon”</a>.) There may be multiple 2019 <span><strong class="command">lwres</strong></span> statements configuring 2020 lightweight resolver servers with different properties. 2021 </p> 2022<p> 2023 The <span><strong class="command">listen-on</strong></span> statement specifies a 2024 list of 2025 addresses (and ports) that this instance of a lightweight resolver 2026 daemon 2027 should accept requests on. If no port is specified, port 921 is 2028 used. 2029 If this statement is omitted, requests will be accepted on 2030 127.0.0.1, 2031 port 921. 2032 </p> 2033<p> 2034 The <span><strong class="command">view</strong></span> statement binds this 2035 instance of a 2036 lightweight resolver daemon to a view in the DNS namespace, so that 2037 the 2038 response will be constructed in the same manner as a normal DNS 2039 query 2040 matching this view. If this statement is omitted, the default view 2041 is 2042 used, and if there is no default view, an error is triggered. 2043 </p> 2044<p> 2045 The <span><strong class="command">search</strong></span> statement is equivalent to 2046 the 2047 <span><strong class="command">search</strong></span> statement in 2048 <code class="filename">/etc/resolv.conf</code>. It provides a 2049 list of domains 2050 which are appended to relative names in queries. 2051 </p> 2052<p> 2053 The <span><strong class="command">ndots</strong></span> statement is equivalent to 2054 the 2055 <span><strong class="command">ndots</strong></span> statement in 2056 <code class="filename">/etc/resolv.conf</code>. It indicates the 2057 minimum 2058 number of dots in a relative domain name that should result in an 2059 exact match lookup before search path elements are appended. 2060 </p> 2061</div> 2062<div class="sect2" lang="en"> 2063<div class="titlepage"><div><div><h3 class="title"> 2064<a name="id2578116"></a><span><strong class="command">masters</strong></span> Statement Grammar</h3></div></div></div> 2065<pre class="programlisting"> 2066<span><strong class="command">masters</strong></span> <em class="replaceable"><code>name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>masters_list</code></em> | 2067 <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] }; 2068</pre> 2069</div> 2070<div class="sect2" lang="en"> 2071<div class="titlepage"><div><div><h3 class="title"> 2072<a name="id2578160"></a><span><strong class="command">masters</strong></span> Statement Definition and 2073 Usage</h3></div></div></div> 2074<p><span><strong class="command">masters</strong></span> 2075 lists allow for a common set of masters to be easily used by 2076 multiple stub and slave zones. 2077 </p> 2078</div> 2079<div class="sect2" lang="en"> 2080<div class="titlepage"><div><div><h3 class="title"> 2081<a name="id2578174"></a><span><strong class="command">options</strong></span> Statement Grammar</h3></div></div></div> 2082<p> 2083 This is the grammar of the <span><strong class="command">options</strong></span> 2084 statement in the <code class="filename">named.conf</code> file: 2085 </p> 2086<pre class="programlisting"><span><strong class="command">options</strong></span> { 2087 [<span class="optional"> attach-cache <em class="replaceable"><code>cache_name</code></em>; </span>] 2088 [<span class="optional"> version <em class="replaceable"><code>version_string</code></em>; </span>] 2089 [<span class="optional"> hostname <em class="replaceable"><code>hostname_string</code></em>; </span>] 2090 [<span class="optional"> server-id <em class="replaceable"><code>server_id_string</code></em>; </span>] 2091 [<span class="optional"> directory <em class="replaceable"><code>path_name</code></em>; </span>] 2092 [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>] 2093 [<span class="optional"> managed-keys-directory <em class="replaceable"><code>path_name</code></em>; </span>] 2094 [<span class="optional"> named-xfer <em class="replaceable"><code>path_name</code></em>; </span>] 2095 [<span class="optional"> tkey-gssapi-keytab <em class="replaceable"><code>path_name</code></em>; </span>] 2096 [<span class="optional"> tkey-gssapi-credential <em class="replaceable"><code>principal</code></em>; </span>] 2097 [<span class="optional"> tkey-domain <em class="replaceable"><code>domainname</code></em>; </span>] 2098 [<span class="optional"> tkey-dhkey <em class="replaceable"><code>key_name</code></em> <em class="replaceable"><code>key_tag</code></em>; </span>] 2099 [<span class="optional"> cache-file <em class="replaceable"><code>path_name</code></em>; </span>] 2100 [<span class="optional"> dump-file <em class="replaceable"><code>path_name</code></em>; </span>] 2101 [<span class="optional"> bindkeys-file <em class="replaceable"><code>path_name</code></em>; </span>] 2102 [<span class="optional"> secroots-file <em class="replaceable"><code>path_name</code></em>; </span>] 2103 [<span class="optional"> session-keyfile <em class="replaceable"><code>path_name</code></em>; </span>] 2104 [<span class="optional"> session-keyname <em class="replaceable"><code>key_name</code></em>; </span>] 2105 [<span class="optional"> session-keyalg <em class="replaceable"><code>algorithm_id</code></em>; </span>] 2106 [<span class="optional"> memstatistics <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2107 [<span class="optional"> memstatistics-file <em class="replaceable"><code>path_name</code></em>; </span>] 2108 [<span class="optional"> pid-file <em class="replaceable"><code>path_name</code></em>; </span>] 2109 [<span class="optional"> recursing-file <em class="replaceable"><code>path_name</code></em>; </span>] 2110 [<span class="optional"> statistics-file <em class="replaceable"><code>path_name</code></em>; </span>] 2111 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2112 [<span class="optional"> auth-nxdomain <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2113 [<span class="optional"> deallocate-on-exit <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2114 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em>; </span>] 2115 [<span class="optional"> fake-iquery <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2116 [<span class="optional"> fetch-glue <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2117 [<span class="optional"> flush-zones-on-shutdown <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2118 [<span class="optional"> has-old-clients <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2119 [<span class="optional"> host-statistics <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2120 [<span class="optional"> host-statistics-max <em class="replaceable"><code>number</code></em>; </span>] 2121 [<span class="optional"> minimal-responses <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2122 [<span class="optional"> multiple-cnames <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2123 [<span class="optional"> notify <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>explicit</code></em> | <em class="replaceable"><code>master-only</code></em>; </span>] 2124 [<span class="optional"> recursion <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2125 [<span class="optional"> rfc2308-type1 <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2126 [<span class="optional"> use-id-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2127 [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2128 [<span class="optional"> ixfr-from-differences (<em class="replaceable"><code>yes_or_no</code></em> | <code class="constant">master</code> | <code class="constant">slave</code>); </span>] 2129 [<span class="optional"> dnssec-enable <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2130 [<span class="optional"> dnssec-validation (<em class="replaceable"><code>yes_or_no</code></em> | <code class="constant">auto</code>); </span>] 2131 [<span class="optional"> dnssec-lookaside ( <em class="replaceable"><code>auto</code></em> | 2132 <em class="replaceable"><code>no</code></em> | 2133 <em class="replaceable"><code>domain</code></em> trust-anchor <em class="replaceable"><code>domain</code></em> ); </span>] 2134 [<span class="optional"> dnssec-must-be-secure <em class="replaceable"><code>domain yes_or_no</code></em>; </span>] 2135 [<span class="optional"> dnssec-accept-expired <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2136 [<span class="optional"> forward ( <em class="replaceable"><code>only</code></em> | <em class="replaceable"><code>first</code></em> ); </span>] 2137 [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] 2138 [<span class="optional"> dual-stack-servers [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { 2139 ( <em class="replaceable"><code>domain_name</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] | 2140 <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ) ; 2141 ... }; </span>] 2142 [<span class="optional"> check-names ( <em class="replaceable"><code>master</code></em> | <em class="replaceable"><code>slave</code></em> | <em class="replaceable"><code>response</code></em> ) 2143 ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>] 2144 [<span class="optional"> check-dup-records ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>] 2145 [<span class="optional"> check-mx ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>] 2146 [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2147 [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2148 [<span class="optional"> check-mx-cname ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>] 2149 [<span class="optional"> check-srv-cname ( <em class="replaceable"><code>warn</code></em> | <em class="replaceable"><code>fail</code></em> | <em class="replaceable"><code>ignore</code></em> ); </span>] 2150 [<span class="optional"> check-sibling <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2151 [<span class="optional"> allow-new-zones { <em class="replaceable"><code>yes_or_no</code></em> }; </span>] 2152 [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2153 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2154 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2155 [<span class="optional"> allow-query-cache { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2156 [<span class="optional"> allow-query-cache-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2157 [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2158 [<span class="optional"> allow-recursion { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2159 [<span class="optional"> allow-recursion-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2160 [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2161 [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2162 [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2163 [<span class="optional"> dnssec-dnskey-kskonly <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2164 [<span class="optional"> dnssec-secure-to-insecure <em class="replaceable"><code>yes_or_no</code></em> ;</span>] 2165 [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2166 [<span class="optional"> allow-v6-synthesis { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2167 [<span class="optional"> blackhole { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2168 [<span class="optional"> use-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>] 2169 [<span class="optional"> avoid-v4-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>] 2170 [<span class="optional"> use-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>] 2171 [<span class="optional"> avoid-v6-udp-ports { <em class="replaceable"><code>port_list</code></em> }; </span>] 2172 [<span class="optional"> listen-on [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em> </span>] { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2173 [<span class="optional"> listen-on-v6 [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em> </span>] { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2174 [<span class="optional"> query-source ( ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> ) 2175 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] | 2176 [<span class="optional"> address ( <em class="replaceable"><code>ip4_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] 2177 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>] 2178 [<span class="optional"> query-source-v6 ( ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> ) 2179 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] | 2180 [<span class="optional"> address ( <em class="replaceable"><code>ip6_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] 2181 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] ) ; </span>] 2182 [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2183 [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>] 2184 [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>] 2185 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em>; </span>] 2186 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em>; </span>] 2187 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em>; </span>] 2188 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em>; </span>] 2189 [<span class="optional"> tcp-clients <em class="replaceable"><code>number</code></em>; </span>] 2190 [<span class="optional"> reserved-sockets <em class="replaceable"><code>number</code></em>; </span>] 2191 [<span class="optional"> recursive-clients <em class="replaceable"><code>number</code></em>; </span>] 2192 [<span class="optional"> serial-query-rate <em class="replaceable"><code>number</code></em>; </span>] 2193 [<span class="optional"> serial-queries <em class="replaceable"><code>number</code></em>; </span>] 2194 [<span class="optional"> tcp-listen-queue <em class="replaceable"><code>number</code></em>; </span>] 2195 [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em>; </span>] 2196 [<span class="optional"> transfers-in <em class="replaceable"><code>number</code></em>; </span>] 2197 [<span class="optional"> transfers-out <em class="replaceable"><code>number</code></em>; </span>] 2198 [<span class="optional"> transfers-per-ns <em class="replaceable"><code>number</code></em>; </span>] 2199 [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 2200 [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 2201 [<span class="optional"> alt-transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 2202 [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) 2203 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 2204 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2205 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>] 2206 [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 2207 [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 2208 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 2209 [<span class="optional"> also-notify { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; 2210 [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] 2211 [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em>; </span>] 2212 [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>] 2213 [<span class="optional"> coresize <em class="replaceable"><code>size_spec</code></em> ; </span>] 2214 [<span class="optional"> datasize <em class="replaceable"><code>size_spec</code></em> ; </span>] 2215 [<span class="optional"> files <em class="replaceable"><code>size_spec</code></em> ; </span>] 2216 [<span class="optional"> stacksize <em class="replaceable"><code>size_spec</code></em> ; </span>] 2217 [<span class="optional"> cleaning-interval <em class="replaceable"><code>number</code></em>; </span>] 2218 [<span class="optional"> heartbeat-interval <em class="replaceable"><code>number</code></em>; </span>] 2219 [<span class="optional"> interface-interval <em class="replaceable"><code>number</code></em>; </span>] 2220 [<span class="optional"> statistics-interval <em class="replaceable"><code>number</code></em>; </span>] 2221 [<span class="optional"> topology { <em class="replaceable"><code>address_match_list</code></em> }</span>]; 2222 [<span class="optional"> sortlist { <em class="replaceable"><code>address_match_list</code></em> }</span>]; 2223 [<span class="optional"> rrset-order { <em class="replaceable"><code>order_spec</code></em> ; [<span class="optional"> <em class="replaceable"><code>order_spec</code></em> ; ... </span>] </span>] }; 2224 [<span class="optional"> lame-ttl <em class="replaceable"><code>number</code></em>; </span>] 2225 [<span class="optional"> max-ncache-ttl <em class="replaceable"><code>number</code></em>; </span>] 2226 [<span class="optional"> max-cache-ttl <em class="replaceable"><code>number</code></em>; </span>] 2227 [<span class="optional"> sig-validity-interval <em class="replaceable"><code>number</code></em> [<span class="optional"><em class="replaceable"><code>number</code></em></span>] ; </span>] 2228 [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>] 2229 [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>] 2230 [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>] 2231 [<span class="optional"> min-roots <em class="replaceable"><code>number</code></em>; </span>] 2232 [<span class="optional"> use-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 2233 [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2234 [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2235 [<span class="optional"> treat-cr-as-space <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 2236 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] 2237 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] 2238 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>] 2239 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>] 2240 [<span class="optional"> port <em class="replaceable"><code>ip_port</code></em>; </span>] 2241 [<span class="optional"> additional-from-auth <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 2242 [<span class="optional"> additional-from-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 2243 [<span class="optional"> random-device <em class="replaceable"><code>path_name</code></em> ; </span>] 2244 [<span class="optional"> max-cache-size <em class="replaceable"><code>size_spec</code></em> ; </span>] 2245 [<span class="optional"> match-mapped-addresses <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2246 [<span class="optional"> filter-aaaa-on-v4 ( <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>break-dnssec</code></em> ); </span>] 2247 [<span class="optional"> filter-aaaa { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2248 [<span class="optional"> dns64 <em class="replaceable"><code>IPv6-prefix</code></em> { 2249 [<span class="optional"> clients { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2250 [<span class="optional"> mapped { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2251 [<span class="optional"> exclude { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 2252 [<span class="optional"> suffix IPv6-address; </span>] 2253 [<span class="optional"> recursive-only <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2254 [<span class="optional"> break-dnssec <em class="replaceable"><code>yes_or_no</code></em>; </span>] 2255 }; </span>]; 2256 [<span class="optional"> dns64-server <em class="replaceable"><code>name</code></em> </span>] 2257 [<span class="optional"> dns64-contact <em class="replaceable"><code>name</code></em> </span>] 2258 [<span class="optional"> preferred-glue ( <em class="replaceable"><code>A</code></em> | <em class="replaceable"><code>AAAA</code></em> | <em class="replaceable"><code>NONE</code></em> ); </span>] 2259 [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em>; </span>] 2260 [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em>; </span>] 2261 [<span class="optional"> root-delegation-only [<span class="optional"> exclude { <em class="replaceable"><code>namelist</code></em> } </span>] ; </span>] 2262 [<span class="optional"> querylog <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 2263 [<span class="optional"> disable-algorithms <em class="replaceable"><code>domain</code></em> { <em class="replaceable"><code>algorithm</code></em>; 2264 [<span class="optional"> <em class="replaceable"><code>algorithm</code></em>; </span>] }; </span>] 2265 [<span class="optional"> acache-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 2266 [<span class="optional"> acache-cleaning-interval <em class="replaceable"><code>number</code></em>; </span>] 2267 [<span class="optional"> max-acache-size <em class="replaceable"><code>size_spec</code></em> ; </span>] 2268 [<span class="optional"> clients-per-query <em class="replaceable"><code>number</code></em> ; </span>] 2269 [<span class="optional"> max-clients-per-query <em class="replaceable"><code>number</code></em> ; </span>] 2270 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>] 2271 [<span class="optional"> empty-server <em class="replaceable"><code>name</code></em> ; </span>] 2272 [<span class="optional"> empty-contact <em class="replaceable"><code>name</code></em> ; </span>] 2273 [<span class="optional"> empty-zones-enable <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 2274 [<span class="optional"> disable-empty-zone <em class="replaceable"><code>zone_name</code></em> ; </span>] 2275 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 2276 [<span class="optional"> zero-no-soa-ttl-cache <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 2277 [<span class="optional"> resolver-query-timeout <em class="replaceable"><code>number</code></em> ; </span>] 2278 [<span class="optional"> deny-answer-addresses { <em class="replaceable"><code>address_match_list</code></em> } [<span class="optional"> except-from { <em class="replaceable"><code>namelist</code></em> } </span>];</span>] 2279 [<span class="optional"> deny-answer-aliases { <em class="replaceable"><code>namelist</code></em> } [<span class="optional"> except-from { <em class="replaceable"><code>namelist</code></em> } </span>];</span>] 2280 [<span class="optional"> response-policy { <em class="replaceable"><code>zone_name</code></em> [<span class="optional"> policy given | disabled | passthru | nxdomain | nodata | cname <em class="replaceable"><code>domain</code></em> </span>] ; } ; </span>] 2281}; 2282</pre> 2283</div> 2284<div class="sect2" lang="en"> 2285<div class="titlepage"><div><div><h3 class="title"> 2286<a name="options"></a><span><strong class="command">options</strong></span> Statement Definition and 2287 Usage</h3></div></div></div> 2288<p> 2289 The <span><strong class="command">options</strong></span> statement sets up global 2290 options 2291 to be used by <acronym class="acronym">BIND</acronym>. This statement 2292 may appear only 2293 once in a configuration file. If there is no <span><strong class="command">options</strong></span> 2294 statement, an options block with each option set to its default will 2295 be used. 2296 </p> 2297<div class="variablelist"><dl> 2298<dt><span class="term"><span><strong class="command">attach-cache</strong></span></span></dt> 2299<dd> 2300<p> 2301 Allows multiple views to share a single cache 2302 database. 2303 Each view has its own cache database by default, but 2304 if multiple views have the same operational policy 2305 for name resolution and caching, those views can 2306 share a single cache to save memory and possibly 2307 improve resolution efficiency by using this option. 2308 </p> 2309<p> 2310 The <span><strong class="command">attach-cache</strong></span> option 2311 may also be specified in <span><strong class="command">view</strong></span> 2312 statements, in which case it overrides the 2313 global <span><strong class="command">attach-cache</strong></span> option. 2314 </p> 2315<p> 2316 The <em class="replaceable"><code>cache_name</code></em> specifies 2317 the cache to be shared. 2318 When the <span><strong class="command">named</strong></span> server configures 2319 views which are supposed to share a cache, it 2320 creates a cache with the specified name for the 2321 first view of these sharing views. 2322 The rest of the views will simply refer to the 2323 already created cache. 2324 </p> 2325<p> 2326 One common configuration to share a cache would be to 2327 allow all views to share a single cache. 2328 This can be done by specifying 2329 the <span><strong class="command">attach-cache</strong></span> as a global 2330 option with an arbitrary name. 2331 </p> 2332<p> 2333 Another possible operation is to allow a subset of 2334 all views to share a cache while the others to 2335 retain their own caches. 2336 For example, if there are three views A, B, and C, 2337 and only A and B should share a cache, specify the 2338 <span><strong class="command">attach-cache</strong></span> option as a view A (or 2339 B)'s option, referring to the other view name: 2340 </p> 2341<pre class="programlisting"> 2342 view "A" { 2343 // this view has its own cache 2344 ... 2345 }; 2346 view "B" { 2347 // this view refers to A's cache 2348 attach-cache "A"; 2349 }; 2350 view "C" { 2351 // this view has its own cache 2352 ... 2353 }; 2354</pre> 2355<p> 2356 Views that share a cache must have the same policy 2357 on configurable parameters that may affect caching. 2358 The current implementation requires the following 2359 configurable options be consistent among these 2360 views: 2361 <span><strong class="command">check-names</strong></span>, 2362 <span><strong class="command">cleaning-interval</strong></span>, 2363 <span><strong class="command">dnssec-accept-expired</strong></span>, 2364 <span><strong class="command">dnssec-validation</strong></span>, 2365 <span><strong class="command">max-cache-ttl</strong></span>, 2366 <span><strong class="command">max-ncache-ttl</strong></span>, 2367 <span><strong class="command">max-cache-size</strong></span>, and 2368 <span><strong class="command">zero-no-soa-ttl</strong></span>. 2369 </p> 2370<p> 2371 Note that there may be other parameters that may 2372 cause confusion if they are inconsistent for 2373 different views that share a single cache. 2374 For example, if these views define different sets of 2375 forwarders that can return different answers for the 2376 same question, sharing the answer does not make 2377 sense or could even be harmful. 2378 It is administrator's responsibility to ensure 2379 configuration differences in different views do 2380 not cause disruption with a shared cache. 2381 </p> 2382</dd> 2383<dt><span class="term"><span><strong class="command">directory</strong></span></span></dt> 2384<dd><p> 2385 The working directory of the server. 2386 Any non-absolute pathnames in the configuration file will be 2387 taken 2388 as relative to this directory. The default location for most 2389 server 2390 output files (e.g. <code class="filename">named.run</code>) 2391 is this directory. 2392 If a directory is not specified, the working directory 2393 defaults to `<code class="filename">.</code>', the directory from 2394 which the server 2395 was started. The directory specified should be an absolute 2396 path. 2397 </p></dd> 2398<dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt> 2399<dd><p> 2400 When performing dynamic update of secure zones, the 2401 directory where the public and private DNSSEC key files 2402 should be found, if different than the current working 2403 directory. (Note that this option has no effect on the 2404 paths for files containing non-DNSSEC keys such as 2405 <code class="filename">bind.keys</code>, 2406 <code class="filename">rndc.key</code> or 2407 <code class="filename">session.key</code>.) 2408 </p></dd> 2409<dt><span class="term"><span><strong class="command">managed-keys-directory</strong></span></span></dt> 2410<dd><p> 2411 The directory used to hold the files used to track managed keys. 2412 By default it is the working directory. It there are no 2413 views then the file <code class="filename">managed-keys.bind</code> 2414 otherwise a SHA256 hash of the view name is used with 2415 <code class="filename">.mkeys</code> extension added. 2416 </p></dd> 2417<dt><span class="term"><span><strong class="command">named-xfer</strong></span></span></dt> 2418<dd><p> 2419 <span class="emphasis"><em>This option is obsolete.</em></span> It 2420 was used in <acronym class="acronym">BIND</acronym> 8 to specify 2421 the pathname to the <span><strong class="command">named-xfer</strong></span> 2422 program. In <acronym class="acronym">BIND</acronym> 9, no separate 2423 <span><strong class="command">named-xfer</strong></span> program is needed; 2424 its functionality is built into the name server. 2425 </p></dd> 2426<dt><span class="term"><span><strong class="command">tkey-gssapi-keytab</strong></span></span></dt> 2427<dd><p> 2428 The KRB5 keytab file to use for GSS-TSIG updates. If 2429 this option is set and tkey-gssapi-credential is not 2430 set, then updates will be allowed with any key 2431 matching a principal in the specified keytab. 2432 </p></dd> 2433<dt><span class="term"><span><strong class="command">tkey-gssapi-credential</strong></span></span></dt> 2434<dd><p> 2435 The security credential with which the server should 2436 authenticate keys requested by the GSS-TSIG protocol. 2437 Currently only Kerberos 5 authentication is available 2438 and the credential is a Kerberos principal which the 2439 server can acquire through the default system key 2440 file, normally <code class="filename">/etc/krb5.keytab</code>. 2441 The location keytab file can be overridden using the 2442 tkey-gssapi-keytab option. Normally this principal is 2443 of the form "<strong class="userinput"><code>DNS/</code></strong><code class="varname">server.domain</code>". 2444 To use GSS-TSIG, <span><strong class="command">tkey-domain</strong></span> must 2445 also be set if a specific keytab is not set with 2446 tkey-gssapi-keytab. 2447 </p></dd> 2448<dt><span class="term"><span><strong class="command">tkey-domain</strong></span></span></dt> 2449<dd><p> 2450 The domain appended to the names of all shared keys 2451 generated with <span><strong class="command">TKEY</strong></span>. When a 2452 client requests a <span><strong class="command">TKEY</strong></span> exchange, 2453 it may or may not specify the desired name for the 2454 key. If present, the name of the shared key will 2455 be <code class="varname">client specified part</code> + 2456 <code class="varname">tkey-domain</code>. Otherwise, the 2457 name of the shared key will be <code class="varname">random hex 2458 digits</code> + <code class="varname">tkey-domain</code>. 2459 In most cases, the <span><strong class="command">domainname</strong></span> 2460 should be the server's domain name, or an otherwise 2461 non-existent subdomain like 2462 "_tkey.<code class="varname">domainname</code>". If you are 2463 using GSS-TSIG, this variable must be defined, unless 2464 you specify a specific keytab using tkey-gssapi-keytab. 2465 </p></dd> 2466<dt><span class="term"><span><strong class="command">tkey-dhkey</strong></span></span></dt> 2467<dd><p> 2468 The Diffie-Hellman key used by the server 2469 to generate shared keys with clients using the Diffie-Hellman 2470 mode 2471 of <span><strong class="command">TKEY</strong></span>. The server must be 2472 able to load the 2473 public and private keys from files in the working directory. 2474 In 2475 most cases, the keyname should be the server's host name. 2476 </p></dd> 2477<dt><span class="term"><span><strong class="command">cache-file</strong></span></span></dt> 2478<dd><p> 2479 This is for testing only. Do not use. 2480 </p></dd> 2481<dt><span class="term"><span><strong class="command">dump-file</strong></span></span></dt> 2482<dd><p> 2483 The pathname of the file the server dumps 2484 the database to when instructed to do so with 2485 <span><strong class="command">rndc dumpdb</strong></span>. 2486 If not specified, the default is <code class="filename">named_dump.db</code>. 2487 </p></dd> 2488<dt><span class="term"><span><strong class="command">memstatistics-file</strong></span></span></dt> 2489<dd><p> 2490 The pathname of the file the server writes memory 2491 usage statistics to on exit. If not specified, 2492 the default is <code class="filename">named.memstats</code>. 2493 </p></dd> 2494<dt><span class="term"><span><strong class="command">pid-file</strong></span></span></dt> 2495<dd><p> 2496 The pathname of the file the server writes its process ID 2497 in. If not specified, the default is 2498 <code class="filename">/var/run/named/named.pid</code>. 2499 The PID file is used by programs that want to send signals to 2500 the running 2501 name server. Specifying <span><strong class="command">pid-file none</strong></span> disables the 2502 use of a PID file — no file will be written and any 2503 existing one will be removed. Note that <span><strong class="command">none</strong></span> 2504 is a keyword, not a filename, and therefore is not enclosed 2505 in 2506 double quotes. 2507 </p></dd> 2508<dt><span class="term"><span><strong class="command">recursing-file</strong></span></span></dt> 2509<dd><p> 2510 The pathname of the file the server dumps 2511 the queries that are currently recursing when instructed 2512 to do so with <span><strong class="command">rndc recursing</strong></span>. 2513 If not specified, the default is <code class="filename">named.recursing</code>. 2514 </p></dd> 2515<dt><span class="term"><span><strong class="command">statistics-file</strong></span></span></dt> 2516<dd><p> 2517 The pathname of the file the server appends statistics 2518 to when instructed to do so using <span><strong class="command">rndc stats</strong></span>. 2519 If not specified, the default is <code class="filename">named.stats</code> in the 2520 server's current directory. The format of the file is 2521 described 2522 in <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called “The Statistics File”</a>. 2523 </p></dd> 2524<dt><span class="term"><span><strong class="command">bindkeys-file</strong></span></span></dt> 2525<dd><p> 2526 The pathname of a file to override the built-in trusted 2527 keys provided by <span><strong class="command">named</strong></span>. 2528 See the discussion of <span><strong class="command">dnssec-lookaside</strong></span> 2529 and <span><strong class="command">dnssec-validation</strong></span> for details. 2530 If not specified, the default is 2531 <code class="filename">/etc/bind.keys</code>. 2532 </p></dd> 2533<dt><span class="term"><span><strong class="command">secroots-file</strong></span></span></dt> 2534<dd><p> 2535 The pathname of the file the server dumps 2536 security roots to when instructed to do so with 2537 <span><strong class="command">rndc secroots</strong></span>. 2538 If not specified, the default is 2539 <code class="filename">named.secroots</code>. 2540 </p></dd> 2541<dt><span class="term"><span><strong class="command">session-keyfile</strong></span></span></dt> 2542<dd><p> 2543 The pathname of the file into which to write a TSIG 2544 session key generated by <span><strong class="command">named</strong></span> for use by 2545 <span><strong class="command">nsupdate -l</strong></span>. If not specified, the 2546 default is <code class="filename">/var/run/named/session.key</code>. 2547 (See <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</a>, and in 2548 particular the discussion of the 2549 <span><strong class="command">update-policy</strong></span> statement's 2550 <strong class="userinput"><code>local</code></strong> option for more 2551 information about this feature.) 2552 </p></dd> 2553<dt><span class="term"><span><strong class="command">session-keyname</strong></span></span></dt> 2554<dd><p> 2555 The key name to use for the TSIG session key. 2556 If not specified, the default is "local-ddns". 2557 </p></dd> 2558<dt><span class="term"><span><strong class="command">session-keyalg</strong></span></span></dt> 2559<dd><p> 2560 The algorithm to use for the TSIG session key. 2561 Valid values are hmac-sha1, hmac-sha224, hmac-sha256, 2562 hmac-sha384, hmac-sha512 and hmac-md5. If not 2563 specified, the default is hmac-sha256. 2564 </p></dd> 2565<dt><span class="term"><span><strong class="command">port</strong></span></span></dt> 2566<dd><p> 2567 The UDP/TCP port number the server uses for 2568 receiving and sending DNS protocol traffic. 2569 The default is 53. This option is mainly intended for server 2570 testing; 2571 a server using a port other than 53 will not be able to 2572 communicate with 2573 the global DNS. 2574 </p></dd> 2575<dt><span class="term"><span><strong class="command">random-device</strong></span></span></dt> 2576<dd><p> 2577 The source of entropy to be used by the server. Entropy is 2578 primarily needed 2579 for DNSSEC operations, such as TKEY transactions and dynamic 2580 update of signed 2581 zones. This options specifies the device (or file) from which 2582 to read 2583 entropy. If this is a file, operations requiring entropy will 2584 fail when the 2585 file has been exhausted. If not specified, the default value 2586 is 2587 <code class="filename">/dev/random</code> 2588 (or equivalent) when present, and none otherwise. The 2589 <span><strong class="command">random-device</strong></span> option takes 2590 effect during 2591 the initial configuration load at server startup time and 2592 is ignored on subsequent reloads. 2593 </p></dd> 2594<dt><span class="term"><span><strong class="command">preferred-glue</strong></span></span></dt> 2595<dd><p> 2596 If specified, the listed type (A or AAAA) will be emitted 2597 before other glue 2598 in the additional section of a query response. 2599 The default is not to prefer any type (NONE). 2600 </p></dd> 2601<dt> 2602<a name="root_delegation_only"></a><span class="term"><span><strong class="command">root-delegation-only</strong></span></span> 2603</dt> 2604<dd> 2605<p> 2606 Turn on enforcement of delegation-only in TLDs 2607 (top level domains) and root zones with an optional 2608 exclude list. 2609 </p> 2610<p> 2611 DS queries are expected to be made to and be answered by 2612 delegation only zones. Such queries and responses are 2613 treated as an exception to delegation-only processing 2614 and are not converted to NXDOMAIN responses provided 2615 a CNAME is not discovered at the query name. 2616 </p> 2617<p> 2618 If a delegation only zone server also serves a child 2619 zone it is not always possible to determine whether 2620 an answer comes from the delegation only zone or the 2621 child zone. SOA NS and DNSKEY records are apex 2622 only records and a matching response that contains 2623 these records or DS is treated as coming from a 2624 child zone. RRSIG records are also examined to see 2625 if they are signed by a child zone or not. The 2626 authority section is also examined to see if there 2627 is evidence that the answer is from the child zone. 2628 Answers that are determined to be from a child zone 2629 are not converted to NXDOMAIN responses. Despite 2630 all these checks there is still a possibility of 2631 false negatives when a child zone is being served. 2632 </p> 2633<p> 2634 Similarly false positives can arise from empty nodes 2635 (no records at the name) in the delegation only zone 2636 when the query type is not ANY. 2637 </p> 2638<p> 2639 Note some TLDs are not delegation only (e.g. "DE", "LV", 2640 "US" and "MUSEUM"). This list is not exhaustive. 2641 </p> 2642<pre class="programlisting"> 2643options { 2644 root-delegation-only exclude { "de"; "lv"; "us"; "museum"; }; 2645}; 2646</pre> 2647</dd> 2648<dt><span class="term"><span><strong class="command">disable-algorithms</strong></span></span></dt> 2649<dd><p> 2650 Disable the specified DNSSEC algorithms at and below the 2651 specified name. 2652 Multiple <span><strong class="command">disable-algorithms</strong></span> 2653 statements are allowed. 2654 Only the most specific will be applied. 2655 </p></dd> 2656<dt><span class="term"><span><strong class="command">dnssec-lookaside</strong></span></span></dt> 2657<dd> 2658<p> 2659 When set, <span><strong class="command">dnssec-lookaside</strong></span> provides the 2660 validator with an alternate method to validate DNSKEY 2661 records at the top of a zone. When a DNSKEY is at or 2662 below a domain specified by the deepest 2663 <span><strong class="command">dnssec-lookaside</strong></span>, and the normal DNSSEC 2664 validation has left the key untrusted, the trust-anchor 2665 will be appended to the key name and a DLV record will be 2666 looked up to see if it can validate the key. If the DLV 2667 record validates a DNSKEY (similarly to the way a DS 2668 record does) the DNSKEY RRset is deemed to be trusted. 2669 </p> 2670<p> 2671 If <span><strong class="command">dnssec-lookaside</strong></span> is set to 2672 <strong class="userinput"><code>auto</code></strong>, then built-in default 2673 values for the DLV domain and trust anchor will be 2674 used, along with a built-in key for validation. 2675 </p> 2676<p> 2677 If <span><strong class="command">dnssec-lookaside</strong></span> is set to 2678 <strong class="userinput"><code>no</code></strong>, then dnssec-lookaside 2679 is not used. 2680 </p> 2681<p> 2682 The default DLV key is stored in the file 2683 <code class="filename">bind.keys</code>; 2684 <span><strong class="command">named</strong></span> will load that key at 2685 startup if <span><strong class="command">dnssec-lookaside</strong></span> is set to 2686 <code class="constant">auto</code>. A copy of the file is 2687 installed along with <acronym class="acronym">BIND</acronym> 9, and is 2688 current as of the release date. If the DLV key expires, a 2689 new copy of <code class="filename">bind.keys</code> can be downloaded 2690 from <a href="" target="_top">https://www.isc.org/solutions/dlv</a>. 2691 </p> 2692<p> 2693 (To prevent problems if <code class="filename">bind.keys</code> is 2694 not found, the current key is also compiled in to 2695 <span><strong class="command">named</strong></span>. Relying on this is not 2696 recommended, however, as it requires <span><strong class="command">named</strong></span> 2697 to be recompiled with a new key when the DLV key expires.) 2698 </p> 2699<p> 2700 NOTE: <span><strong class="command">named</strong></span> only loads certain specific 2701 keys from <code class="filename">bind.keys</code>: those for the 2702 DLV zone and for the DNS root zone. The file cannot be 2703 used to store keys for other zones. 2704 </p> 2705</dd> 2706<dt><span class="term"><span><strong class="command">dnssec-must-be-secure</strong></span></span></dt> 2707<dd><p> 2708 Specify hierarchies which must be or may not be secure 2709 (signed and validated). If <strong class="userinput"><code>yes</code></strong>, 2710 then <span><strong class="command">named</strong></span> will only accept answers if 2711 they are secure. If <strong class="userinput"><code>no</code></strong>, then normal 2712 DNSSEC validation applies allowing for insecure answers to 2713 be accepted. The specified domain must be under a 2714 <span><strong class="command">trusted-keys</strong></span> or 2715 <span><strong class="command">managed-keys</strong></span> statement, or 2716 <span><strong class="command">dnssec-lookaside</strong></span> must be active. 2717 </p></dd> 2718<dt><span class="term"><span><strong class="command">dns64</strong></span></span></dt> 2719<dd> 2720<p> 2721 This directive instructs <span><strong class="command">named</strong></span> to 2722 return mapped IPv4 addresses to AAAA queries when 2723 there are no AAAA records. It is intended to be 2724 used in conjunction with a NAT64. Each 2725 <span><strong class="command">dns64</strong></span> defines one DNS64 prefix. 2726 Multiple DNS64 prefixes can be defined. 2727 </p> 2728<p> 2729 Compatible IPv6 prefixes have lengths of 32, 40, 48, 56, 2730 64 and 96 as per RFC 6052. 2731 </p> 2732<p> 2733 Additionally a reverse IP6.ARPA zone will be created for 2734 the prefix to provide a mapping from the IP6.ARPA names 2735 to the corresponding IN-ADDR.ARPA names using synthesized 2736 CNAMEs. <span><strong class="command">dns64-server</strong></span> and 2737 <span><strong class="command">dns64-contact</strong></span> can be used to specify 2738 the name of the server and contact for the zones. These 2739 are settable at the view / options level. These are 2740 not settable on a per-prefix basis. 2741 </p> 2742<p> 2743 Each <span><strong class="command">dns64</strong></span> supports an optional 2744 <span><strong class="command">clients</strong></span> ACL that determines which 2745 clients are affected by this directive. If not defined, 2746 it defaults to <strong class="userinput"><code>any;</code></strong>. 2747 </p> 2748<p> 2749 Each <span><strong class="command">dns64</strong></span> supports an optional 2750 <span><strong class="command">mapped</strong></span> ACL that selects which 2751 IPv4 addresses are to be mapped in the corresponding 2752 A RRset. If not defined it defaults to 2753 <strong class="userinput"><code>any;</code></strong>. 2754 </p> 2755<p> 2756 Normally, DNS64 won't apply to a domain name that 2757 owns one or more AAAA records; these records will 2758 simply be returned. The optional 2759 <span><strong class="command">exclude</strong></span> ACL allows specification 2760 of a list of IPv6 addresses that will be ignored 2761 if they appear in a domain name's AAAA records, and 2762 DNS64 will be applied to any A records the domain 2763 name owns. If not defined, <span><strong class="command">exclude</strong></span> 2764 defaults to none. 2765 </p> 2766<p> 2767 A optional <span><strong class="command">suffix</strong></span> can also 2768 be defined to set the bits trailing the mapped 2769 IPv4 address bits. By default these bits are 2770 set to <strong class="userinput"><code>::</code></strong>. The bits 2771 matching the prefix and mapped IPv4 address 2772 must be zero. 2773 </p> 2774<p> 2775 If <span><strong class="command">recursive-only</strong></span> is set to 2776 <span><strong class="command">yes</strong></span> the DNS64 synthesis will 2777 only happen for recursive queries. The default 2778 is <span><strong class="command">no</strong></span>. 2779 </p> 2780<p> 2781 If <span><strong class="command">break-dnssec</strong></span> is set to 2782 <span><strong class="command">yes</strong></span> the DNS64 synthesis will 2783 happen even if the result, if validated, would 2784 cause a DNSSEC validation failure. If this option 2785 is set to <span><strong class="command">no</strong></span> (the default), the DO 2786 is set on the incoming query, and there are RRSIGs on 2787 the applicable records, then synthesis will not happen. 2788 </p> 2789<pre class="programlisting"> 2790 acl rfc1918 { 10/8; 192.168/16; 172.16/12; }; 2791 2792 dns64 64:FF9B::/96 { 2793 clients { any; }; 2794 mapped { !rfc1918; any; }; 2795 exclude { 64:FF9B::/96; ::ffff:0000:0000/96; }; 2796 suffix ::; 2797 }; 2798</pre> 2799</dd> 2800</dl></div> 2801<div class="sect3" lang="en"> 2802<div class="titlepage"><div><div><h4 class="title"> 2803<a name="boolean_options"></a>Boolean Options</h4></div></div></div> 2804<div class="variablelist"><dl> 2805<dt><span class="term"><span><strong class="command">allow-new-zones</strong></span></span></dt> 2806<dd><p> 2807 If <strong class="userinput"><code>yes</code></strong>, then zones can be 2808 added at runtime via <span><strong class="command">rndc addzone</strong></span> 2809 or deleted via <span><strong class="command">rndc delzone</strong></span>. 2810 The default is <strong class="userinput"><code>no</code></strong>. 2811 </p></dd> 2812<dt><span class="term"><span><strong class="command">auth-nxdomain</strong></span></span></dt> 2813<dd><p> 2814 If <strong class="userinput"><code>yes</code></strong>, then the <span><strong class="command">AA</strong></span> bit 2815 is always set on NXDOMAIN responses, even if the server is 2816 not actually 2817 authoritative. The default is <strong class="userinput"><code>no</code></strong>; 2818 this is 2819 a change from <acronym class="acronym">BIND</acronym> 8. If you 2820 are using very old DNS software, you 2821 may need to set it to <strong class="userinput"><code>yes</code></strong>. 2822 </p></dd> 2823<dt><span class="term"><span><strong class="command">deallocate-on-exit</strong></span></span></dt> 2824<dd><p> 2825 This option was used in <acronym class="acronym">BIND</acronym> 2826 8 to enable checking 2827 for memory leaks on exit. <acronym class="acronym">BIND</acronym> 9 ignores the option and always performs 2828 the checks. 2829 </p></dd> 2830<dt><span class="term"><span><strong class="command">memstatistics</strong></span></span></dt> 2831<dd><p> 2832 Write memory statistics to the file specified by 2833 <span><strong class="command">memstatistics-file</strong></span> at exit. 2834 The default is <strong class="userinput"><code>no</code></strong> unless 2835 '-m record' is specified on the command line in 2836 which case it is <strong class="userinput"><code>yes</code></strong>. 2837 </p></dd> 2838<dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt> 2839<dd> 2840<p> 2841 If <strong class="userinput"><code>yes</code></strong>, then the 2842 server treats all zones as if they are doing zone transfers 2843 across 2844 a dial-on-demand dialup link, which can be brought up by 2845 traffic 2846 originating from this server. This has different effects 2847 according 2848 to zone type and concentrates the zone maintenance so that 2849 it all 2850 happens in a short interval, once every <span><strong class="command">heartbeat-interval</strong></span> and 2851 hopefully during the one call. It also suppresses some of 2852 the normal 2853 zone maintenance traffic. The default is <strong class="userinput"><code>no</code></strong>. 2854 </p> 2855<p> 2856 The <span><strong class="command">dialup</strong></span> option 2857 may also be specified in the <span><strong class="command">view</strong></span> and 2858 <span><strong class="command">zone</strong></span> statements, 2859 in which case it overrides the global <span><strong class="command">dialup</strong></span> 2860 option. 2861 </p> 2862<p> 2863 If the zone is a master zone, then the server will send out a 2864 NOTIFY 2865 request to all the slaves (default). This should trigger the 2866 zone serial 2867 number check in the slave (providing it supports NOTIFY) 2868 allowing the slave 2869 to verify the zone while the connection is active. 2870 The set of servers to which NOTIFY is sent can be controlled 2871 by 2872 <span><strong class="command">notify</strong></span> and <span><strong class="command">also-notify</strong></span>. 2873 </p> 2874<p> 2875 If the 2876 zone is a slave or stub zone, then the server will suppress 2877 the regular 2878 "zone up to date" (refresh) queries and only perform them 2879 when the 2880 <span><strong class="command">heartbeat-interval</strong></span> expires in 2881 addition to sending 2882 NOTIFY requests. 2883 </p> 2884<p> 2885 Finer control can be achieved by using 2886 <strong class="userinput"><code>notify</code></strong> which only sends NOTIFY 2887 messages, 2888 <strong class="userinput"><code>notify-passive</code></strong> which sends NOTIFY 2889 messages and 2890 suppresses the normal refresh queries, <strong class="userinput"><code>refresh</code></strong> 2891 which suppresses normal refresh processing and sends refresh 2892 queries 2893 when the <span><strong class="command">heartbeat-interval</strong></span> 2894 expires, and 2895 <strong class="userinput"><code>passive</code></strong> which just disables normal 2896 refresh 2897 processing. 2898 </p> 2899<div class="informaltable"><table border="1"> 2900<colgroup> 2901<col> 2902<col> 2903<col> 2904<col> 2905</colgroup> 2906<tbody> 2907<tr> 2908<td> 2909 <p> 2910 dialup mode 2911 </p> 2912 </td> 2913<td> 2914 <p> 2915 normal refresh 2916 </p> 2917 </td> 2918<td> 2919 <p> 2920 heart-beat refresh 2921 </p> 2922 </td> 2923<td> 2924 <p> 2925 heart-beat notify 2926 </p> 2927 </td> 2928</tr> 2929<tr> 2930<td> 2931 <p><span><strong class="command">no</strong></span> (default)</p> 2932 </td> 2933<td> 2934 <p> 2935 yes 2936 </p> 2937 </td> 2938<td> 2939 <p> 2940 no 2941 </p> 2942 </td> 2943<td> 2944 <p> 2945 no 2946 </p> 2947 </td> 2948</tr> 2949<tr> 2950<td> 2951 <p><span><strong class="command">yes</strong></span></p> 2952 </td> 2953<td> 2954 <p> 2955 no 2956 </p> 2957 </td> 2958<td> 2959 <p> 2960 yes 2961 </p> 2962 </td> 2963<td> 2964 <p> 2965 yes 2966 </p> 2967 </td> 2968</tr> 2969<tr> 2970<td> 2971 <p><span><strong class="command">notify</strong></span></p> 2972 </td> 2973<td> 2974 <p> 2975 yes 2976 </p> 2977 </td> 2978<td> 2979 <p> 2980 no 2981 </p> 2982 </td> 2983<td> 2984 <p> 2985 yes 2986 </p> 2987 </td> 2988</tr> 2989<tr> 2990<td> 2991 <p><span><strong class="command">refresh</strong></span></p> 2992 </td> 2993<td> 2994 <p> 2995 no 2996 </p> 2997 </td> 2998<td> 2999 <p> 3000 yes 3001 </p> 3002 </td> 3003<td> 3004 <p> 3005 no 3006 </p> 3007 </td> 3008</tr> 3009<tr> 3010<td> 3011 <p><span><strong class="command">passive</strong></span></p> 3012 </td> 3013<td> 3014 <p> 3015 no 3016 </p> 3017 </td> 3018<td> 3019 <p> 3020 no 3021 </p> 3022 </td> 3023<td> 3024 <p> 3025 no 3026 </p> 3027 </td> 3028</tr> 3029<tr> 3030<td> 3031 <p><span><strong class="command">notify-passive</strong></span></p> 3032 </td> 3033<td> 3034 <p> 3035 no 3036 </p> 3037 </td> 3038<td> 3039 <p> 3040 no 3041 </p> 3042 </td> 3043<td> 3044 <p> 3045 yes 3046 </p> 3047 </td> 3048</tr> 3049</tbody> 3050</table></div> 3051<p> 3052 Note that normal NOTIFY processing is not affected by 3053 <span><strong class="command">dialup</strong></span>. 3054 </p> 3055</dd> 3056<dt><span class="term"><span><strong class="command">fake-iquery</strong></span></span></dt> 3057<dd><p> 3058 In <acronym class="acronym">BIND</acronym> 8, this option 3059 enabled simulating the obsolete DNS query type 3060 IQUERY. <acronym class="acronym">BIND</acronym> 9 never does 3061 IQUERY simulation. 3062 </p></dd> 3063<dt><span class="term"><span><strong class="command">fetch-glue</strong></span></span></dt> 3064<dd><p> 3065 This option is obsolete. 3066 In BIND 8, <strong class="userinput"><code>fetch-glue yes</code></strong> 3067 caused the server to attempt to fetch glue resource records 3068 it 3069 didn't have when constructing the additional 3070 data section of a response. This is now considered a bad 3071 idea 3072 and BIND 9 never does it. 3073 </p></dd> 3074<dt><span class="term"><span><strong class="command">flush-zones-on-shutdown</strong></span></span></dt> 3075<dd><p> 3076 When the nameserver exits due receiving SIGTERM, 3077 flush or do not flush any pending zone writes. The default 3078 is 3079 <span><strong class="command">flush-zones-on-shutdown</strong></span> <strong class="userinput"><code>no</code></strong>. 3080 </p></dd> 3081<dt><span class="term"><span><strong class="command">has-old-clients</strong></span></span></dt> 3082<dd><p> 3083 This option was incorrectly implemented 3084 in <acronym class="acronym">BIND</acronym> 8, and is ignored by <acronym class="acronym">BIND</acronym> 9. 3085 To achieve the intended effect 3086 of 3087 <span><strong class="command">has-old-clients</strong></span> <strong class="userinput"><code>yes</code></strong>, specify 3088 the two separate options <span><strong class="command">auth-nxdomain</strong></span> <strong class="userinput"><code>yes</code></strong> 3089 and <span><strong class="command">rfc2308-type1</strong></span> <strong class="userinput"><code>no</code></strong> instead. 3090 </p></dd> 3091<dt><span class="term"><span><strong class="command">host-statistics</strong></span></span></dt> 3092<dd><p> 3093 In BIND 8, this enables keeping of 3094 statistics for every host that the name server interacts 3095 with. 3096 Not implemented in BIND 9. 3097 </p></dd> 3098<dt><span class="term"><span><strong class="command">maintain-ixfr-base</strong></span></span></dt> 3099<dd><p> 3100 <span class="emphasis"><em>This option is obsolete</em></span>. 3101 It was used in <acronym class="acronym">BIND</acronym> 8 to 3102 determine whether a transaction log was 3103 kept for Incremental Zone Transfer. <acronym class="acronym">BIND</acronym> 9 maintains a transaction 3104 log whenever possible. If you need to disable outgoing 3105 incremental zone 3106 transfers, use <span><strong class="command">provide-ixfr</strong></span> <strong class="userinput"><code>no</code></strong>. 3107 </p></dd> 3108<dt><span class="term"><span><strong class="command">minimal-responses</strong></span></span></dt> 3109<dd><p> 3110 If <strong class="userinput"><code>yes</code></strong>, then when generating 3111 responses the server will only add records to the authority 3112 and additional data sections when they are required (e.g. 3113 delegations, negative responses). This may improve the 3114 performance of the server. 3115 The default is <strong class="userinput"><code>no</code></strong>. 3116 </p></dd> 3117<dt><span class="term"><span><strong class="command">multiple-cnames</strong></span></span></dt> 3118<dd><p> 3119 This option was used in <acronym class="acronym">BIND</acronym> 8 to allow 3120 a domain name to have multiple CNAME records in violation of 3121 the DNS standards. <acronym class="acronym">BIND</acronym> 9.2 onwards 3122 always strictly enforces the CNAME rules both in master 3123 files and dynamic updates. 3124 </p></dd> 3125<dt><span class="term"><span><strong class="command">notify</strong></span></span></dt> 3126<dd> 3127<p> 3128 If <strong class="userinput"><code>yes</code></strong> (the default), 3129 DNS NOTIFY messages are sent when a zone the server is 3130 authoritative for 3131 changes, see <a href="Bv9ARM.ch04.html#notify" title="Notify">the section called “Notify”</a>. The messages are 3132 sent to the 3133 servers listed in the zone's NS records (except the master 3134 server identified 3135 in the SOA MNAME field), and to any servers listed in the 3136 <span><strong class="command">also-notify</strong></span> option. 3137 </p> 3138<p> 3139 If <strong class="userinput"><code>master-only</code></strong>, notifies are only 3140 sent 3141 for master zones. 3142 If <strong class="userinput"><code>explicit</code></strong>, notifies are sent only 3143 to 3144 servers explicitly listed using <span><strong class="command">also-notify</strong></span>. 3145 If <strong class="userinput"><code>no</code></strong>, no notifies are sent. 3146 </p> 3147<p> 3148 The <span><strong class="command">notify</strong></span> option may also be 3149 specified in the <span><strong class="command">zone</strong></span> 3150 statement, 3151 in which case it overrides the <span><strong class="command">options notify</strong></span> statement. 3152 It would only be necessary to turn off this option if it 3153 caused slaves 3154 to crash. 3155 </p> 3156</dd> 3157<dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt> 3158<dd><p> 3159 If <strong class="userinput"><code>yes</code></strong> do not check the nameservers 3160 in the NS RRset against the SOA MNAME. Normally a NOTIFY 3161 message is not sent to the SOA MNAME (SOA ORIGIN) as it is 3162 supposed to contain the name of the ultimate master. 3163 Sometimes, however, a slave is listed as the SOA MNAME in 3164 hidden master configurations and in that case you would 3165 want the ultimate master to still send NOTIFY messages to 3166 all the nameservers listed in the NS RRset. 3167 </p></dd> 3168<dt><span class="term"><span><strong class="command">recursion</strong></span></span></dt> 3169<dd><p> 3170 If <strong class="userinput"><code>yes</code></strong>, and a 3171 DNS query requests recursion, then the server will attempt 3172 to do 3173 all the work required to answer the query. If recursion is 3174 off 3175 and the server does not already know the answer, it will 3176 return a 3177 referral response. The default is 3178 <strong class="userinput"><code>yes</code></strong>. 3179 Note that setting <span><strong class="command">recursion no</strong></span> does not prevent 3180 clients from getting data from the server's cache; it only 3181 prevents new data from being cached as an effect of client 3182 queries. 3183 Caching may still occur as an effect the server's internal 3184 operation, such as NOTIFY address lookups. 3185 See also <span><strong class="command">fetch-glue</strong></span> above. 3186 </p></dd> 3187<dt><span class="term"><span><strong class="command">rfc2308-type1</strong></span></span></dt> 3188<dd> 3189<p> 3190 Setting this to <strong class="userinput"><code>yes</code></strong> will 3191 cause the server to send NS records along with the SOA 3192 record for negative 3193 answers. The default is <strong class="userinput"><code>no</code></strong>. 3194 </p> 3195<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 3196<h3 class="title">Note</h3> 3197<p> 3198 Not yet implemented in <acronym class="acronym">BIND</acronym> 3199 9. 3200 </p> 3201</div> 3202</dd> 3203<dt><span class="term"><span><strong class="command">use-id-pool</strong></span></span></dt> 3204<dd><p> 3205 <span class="emphasis"><em>This option is obsolete</em></span>. 3206 <acronym class="acronym">BIND</acronym> 9 always allocates query 3207 IDs from a pool. 3208 </p></dd> 3209<dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt> 3210<dd><p> 3211 If <strong class="userinput"><code>yes</code></strong>, the server will collect 3212 statistical data on all zones (unless specifically turned 3213 off 3214 on a per-zone basis by specifying <span><strong class="command">zone-statistics no</strong></span> 3215 in the <span><strong class="command">zone</strong></span> statement). 3216 The default is <strong class="userinput"><code>no</code></strong>. 3217 These statistics may be accessed 3218 using <span><strong class="command">rndc stats</strong></span>, which will 3219 dump them to the file listed 3220 in the <span><strong class="command">statistics-file</strong></span>. See 3221 also <a href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called “The Statistics File”</a>. 3222 </p></dd> 3223<dt><span class="term"><span><strong class="command">use-ixfr</strong></span></span></dt> 3224<dd><p> 3225 <span class="emphasis"><em>This option is obsolete</em></span>. 3226 If you need to disable IXFR to a particular server or 3227 servers, see 3228 the information on the <span><strong class="command">provide-ixfr</strong></span> option 3229 in <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and 3230 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and 3231 Usage”</a>. 3232 See also 3233 <a href="Bv9ARM.ch04.html#incremental_zone_transfers" title="Incremental Zone Transfers (IXFR)">the section called “Incremental Zone Transfers (IXFR)”</a>. 3234 </p></dd> 3235<dt><span class="term"><span><strong class="command">provide-ixfr</strong></span></span></dt> 3236<dd><p> 3237 See the description of 3238 <span><strong class="command">provide-ixfr</strong></span> in 3239 <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and 3240 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and 3241 Usage”</a>. 3242 </p></dd> 3243<dt><span class="term"><span><strong class="command">request-ixfr</strong></span></span></dt> 3244<dd><p> 3245 See the description of 3246 <span><strong class="command">request-ixfr</strong></span> in 3247 <a href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and 3248 Usage">the section called “<span><strong class="command">server</strong></span> Statement Definition and 3249 Usage”</a>. 3250 </p></dd> 3251<dt><span class="term"><span><strong class="command">treat-cr-as-space</strong></span></span></dt> 3252<dd><p> 3253 This option was used in <acronym class="acronym">BIND</acronym> 3254 8 to make 3255 the server treat carriage return ("<span><strong class="command">\r</strong></span>") characters the same way 3256 as a space or tab character, 3257 to facilitate loading of zone files on a UNIX system that 3258 were generated 3259 on an NT or DOS machine. In <acronym class="acronym">BIND</acronym> 9, both UNIX "<span><strong class="command">\n</strong></span>" 3260 and NT/DOS "<span><strong class="command">\r\n</strong></span>" newlines 3261 are always accepted, 3262 and the option is ignored. 3263 </p></dd> 3264<dt> 3265<span class="term"><span><strong class="command">additional-from-auth</strong></span>, </span><span class="term"><span><strong class="command">additional-from-cache</strong></span></span> 3266</dt> 3267<dd> 3268<p> 3269 These options control the behavior of an authoritative 3270 server when 3271 answering queries which have additional data, or when 3272 following CNAME 3273 and DNAME chains. 3274 </p> 3275<p> 3276 When both of these options are set to <strong class="userinput"><code>yes</code></strong> 3277 (the default) and a 3278 query is being answered from authoritative data (a zone 3279 configured into the server), the additional data section of 3280 the 3281 reply will be filled in using data from other authoritative 3282 zones 3283 and from the cache. In some situations this is undesirable, 3284 such 3285 as when there is concern over the correctness of the cache, 3286 or 3287 in servers where slave zones may be added and modified by 3288 untrusted third parties. Also, avoiding 3289 the search for this additional data will speed up server 3290 operations 3291 at the possible expense of additional queries to resolve 3292 what would 3293 otherwise be provided in the additional section. 3294 </p> 3295<p> 3296 For example, if a query asks for an MX record for host <code class="literal">foo.example.com</code>, 3297 and the record found is "<code class="literal">MX 10 mail.example.net</code>", normally the address 3298 records (A and AAAA) for <code class="literal">mail.example.net</code> will be provided as well, 3299 if known, even though they are not in the example.com zone. 3300 Setting these options to <span><strong class="command">no</strong></span> 3301 disables this behavior and makes 3302 the server only search for additional data in the zone it 3303 answers from. 3304 </p> 3305<p> 3306 These options are intended for use in authoritative-only 3307 servers, or in authoritative-only views. Attempts to set 3308 them to <span><strong class="command">no</strong></span> without also 3309 specifying 3310 <span><strong class="command">recursion no</strong></span> will cause the 3311 server to 3312 ignore the options and log a warning message. 3313 </p> 3314<p> 3315 Specifying <span><strong class="command">additional-from-cache no</strong></span> actually 3316 disables the use of the cache not only for additional data 3317 lookups 3318 but also when looking up the answer. This is usually the 3319 desired 3320 behavior in an authoritative-only server where the 3321 correctness of 3322 the cached data is an issue. 3323 </p> 3324<p> 3325 When a name server is non-recursively queried for a name 3326 that is not 3327 below the apex of any served zone, it normally answers with 3328 an 3329 "upwards referral" to the root servers or the servers of 3330 some other 3331 known parent of the query name. Since the data in an 3332 upwards referral 3333 comes from the cache, the server will not be able to provide 3334 upwards 3335 referrals when <span><strong class="command">additional-from-cache no</strong></span> 3336 has been specified. Instead, it will respond to such 3337 queries 3338 with REFUSED. This should not cause any problems since 3339 upwards referrals are not required for the resolution 3340 process. 3341 </p> 3342</dd> 3343<dt><span class="term"><span><strong class="command">match-mapped-addresses</strong></span></span></dt> 3344<dd> 3345<p> 3346 If <strong class="userinput"><code>yes</code></strong>, then an 3347 IPv4-mapped IPv6 address will match any address match 3348 list entries that match the corresponding IPv4 address. 3349 </p> 3350<p> 3351 This option was introduced to work around a kernel quirk 3352 in some operating systems that causes IPv4 TCP 3353 connections, such as zone transfers, to be accepted on an 3354 IPv6 socket using mapped addresses. This caused address 3355 match lists designed for IPv4 to fail to match. However, 3356 <span><strong class="command">named</strong></span> now solves this problem 3357 internally. The use of this option is discouraged. 3358 </p> 3359</dd> 3360<dt><span class="term"><span><strong class="command">filter-aaaa-on-v4</strong></span></span></dt> 3361<dd> 3362<p> 3363 This option is only available when 3364 <acronym class="acronym">BIND</acronym> 9 is compiled with the 3365 <strong class="userinput"><code>--enable-filter-aaaa</code></strong> option on the 3366 "configure" command line. It is intended to help the 3367 transition from IPv4 to IPv6 by not giving IPv6 addresses 3368 to DNS clients unless they have connections to the IPv6 3369 Internet. This is not recommended unless absolutely 3370 necessary. The default is <strong class="userinput"><code>no</code></strong>. 3371 The <span><strong class="command">filter-aaaa-on-v4</strong></span> option 3372 may also be specified in <span><strong class="command">view</strong></span> statements 3373 to override the global <span><strong class="command">filter-aaaa-on-v4</strong></span> 3374 option. 3375 </p> 3376<p> 3377 If <strong class="userinput"><code>yes</code></strong>, 3378 the DNS client is at an IPv4 address, in <span><strong class="command">filter-aaaa</strong></span>, 3379 and if the response does not include DNSSEC signatures, 3380 then all AAAA records are deleted from the response. 3381 This filtering applies to all responses and not only 3382 authoritative responses. 3383 </p> 3384<p> 3385 If <strong class="userinput"><code>break-dnssec</code></strong>, 3386 then AAAA records are deleted even when dnssec is enabled. 3387 As suggested by the name, this makes the response not verify, 3388 because the DNSSEC protocol is designed detect deletions. 3389 </p> 3390<p> 3391 This mechanism can erroneously cause other servers to 3392 not give AAAA records to their clients. 3393 A recursing server with both IPv6 and IPv4 network connections 3394 that queries an authoritative server using this mechanism 3395 via IPv4 will be denied AAAA records even if its client is 3396 using IPv6. 3397 </p> 3398<p> 3399 This mechanism is applied to authoritative as well as 3400 non-authoritative records. 3401 A client using IPv4 that is not allowed recursion can 3402 erroneously be given AAAA records because the server is not 3403 allowed to check for A records. 3404 </p> 3405<p> 3406 Some AAAA records are given to IPv4 clients in glue records. 3407 IPv4 clients that are servers can then erroneously 3408 answer requests for AAAA records received via IPv4. 3409 </p> 3410</dd> 3411<dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt> 3412<dd> 3413<p> 3414 When <strong class="userinput"><code>yes</code></strong> and the server loads a new version of a master 3415 zone from its zone file or receives a new version of a slave 3416 file by a non-incremental zone transfer, it will compare 3417 the new version to the previous one and calculate a set 3418 of differences. The differences are then logged in the 3419 zone's journal file such that the changes can be transmitted 3420 to downstream slaves as an incremental zone transfer. 3421 </p> 3422<p> 3423 By allowing incremental zone transfers to be used for 3424 non-dynamic zones, this option saves bandwidth at the 3425 expense of increased CPU and memory consumption at the 3426 master. 3427 In particular, if the new version of a zone is completely 3428 different from the previous one, the set of differences 3429 will be of a size comparable to the combined size of the 3430 old and new zone version, and the server will need to 3431 temporarily allocate memory to hold this complete 3432 difference set. 3433 </p> 3434<p><span><strong class="command">ixfr-from-differences</strong></span> 3435 also accepts <span><strong class="command">master</strong></span> and 3436 <span><strong class="command">slave</strong></span> at the view and options 3437 levels which causes 3438 <span><strong class="command">ixfr-from-differences</strong></span> to be enabled for 3439 all <span><strong class="command">master</strong></span> or 3440 <span><strong class="command">slave</strong></span> zones respectively. 3441 It is off by default. 3442 </p> 3443</dd> 3444<dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt> 3445<dd><p> 3446 This should be set when you have multiple masters for a zone 3447 and the 3448 addresses refer to different machines. If <strong class="userinput"><code>yes</code></strong>, <span><strong class="command">named</strong></span> will 3449 not log 3450 when the serial number on the master is less than what <span><strong class="command">named</strong></span> 3451 currently 3452 has. The default is <strong class="userinput"><code>no</code></strong>. 3453 </p></dd> 3454<dt><span class="term"><span><strong class="command">dnssec-enable</strong></span></span></dt> 3455<dd><p> 3456 Enable DNSSEC support in <span><strong class="command">named</strong></span>. Unless set to <strong class="userinput"><code>yes</code></strong>, 3457 <span><strong class="command">named</strong></span> behaves as if it does not support DNSSEC. 3458 The default is <strong class="userinput"><code>yes</code></strong>. 3459 </p></dd> 3460<dt><span class="term"><span><strong class="command">dnssec-validation</strong></span></span></dt> 3461<dd><p> 3462 Enable DNSSEC validation in <span><strong class="command">named</strong></span>. 3463 Note <span><strong class="command">dnssec-enable</strong></span> also needs to be 3464 set to <strong class="userinput"><code>yes</code></strong> to be effective. 3465 If set to <strong class="userinput"><code>no</code></strong>, DNSSEC validation 3466 is disabled. If set to <strong class="userinput"><code>auto</code></strong>, 3467 DNSSEC validation is enabled, and a default 3468 trust-anchor for the DNS root zone is used. If set to 3469 <strong class="userinput"><code>yes</code></strong>, DNSSEC validation is enabled, 3470 but a trust anchor must be manually configured using 3471 a <span><strong class="command">trusted-keys</strong></span> or 3472 <span><strong class="command">managed-keys</strong></span> statement. The default 3473 is <strong class="userinput"><code>yes</code></strong>. 3474 </p></dd> 3475<dt><span class="term"><span><strong class="command">dnssec-accept-expired</strong></span></span></dt> 3476<dd><p> 3477 Accept expired signatures when verifying DNSSEC signatures. 3478 The default is <strong class="userinput"><code>no</code></strong>. 3479 Setting this option to <strong class="userinput"><code>yes</code></strong> 3480 leaves <span><strong class="command">named</strong></span> vulnerable to 3481 replay attacks. 3482 </p></dd> 3483<dt><span class="term"><span><strong class="command">querylog</strong></span></span></dt> 3484<dd><p> 3485 Specify whether query logging should be started when <span><strong class="command">named</strong></span> 3486 starts. 3487 If <span><strong class="command">querylog</strong></span> is not specified, 3488 then the query logging 3489 is determined by the presence of the logging category <span><strong class="command">queries</strong></span>. 3490 </p></dd> 3491<dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt> 3492<dd> 3493<p> 3494 This option is used to restrict the character set and syntax 3495 of 3496 certain domain names in master files and/or DNS responses 3497 received 3498 from the network. The default varies according to usage 3499 area. For 3500 <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>. 3501 For <span><strong class="command">slave</strong></span> zones the default 3502 is <span><strong class="command">warn</strong></span>. 3503 For answers received from the network (<span><strong class="command">response</strong></span>) 3504 the default is <span><strong class="command">ignore</strong></span>. 3505 </p> 3506<p> 3507 The rules for legal hostnames and mail domains are derived 3508 from RFC 952 and RFC 821 as modified by RFC 1123. 3509 </p> 3510<p><span><strong class="command">check-names</strong></span> 3511 applies to the owner names of A, AAAA and MX records. 3512 It also applies to the domain names in the RDATA of NS, SOA, 3513 MX, and SRV records. 3514 It also applies to the RDATA of PTR records where the owner 3515 name indicated that it is a reverse lookup of a hostname 3516 (the owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT). 3517 </p> 3518</dd> 3519<dt><span class="term"><span><strong class="command">check-dup-records</strong></span></span></dt> 3520<dd><p> 3521 Check master zones for records that are treated as different 3522 by DNSSEC but are semantically equal in plain DNS. The 3523 default is to <span><strong class="command">warn</strong></span>. Other possible 3524 values are <span><strong class="command">fail</strong></span> and 3525 <span><strong class="command">ignore</strong></span>. 3526 </p></dd> 3527<dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt> 3528<dd><p> 3529 Check whether the MX record appears to refer to a IP address. 3530 The default is to <span><strong class="command">warn</strong></span>. Other possible 3531 values are <span><strong class="command">fail</strong></span> and 3532 <span><strong class="command">ignore</strong></span>. 3533 </p></dd> 3534<dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt> 3535<dd><p> 3536 This option is used to check for non-terminal wildcards. 3537 The use of non-terminal wildcards is almost always as a 3538 result of a failure 3539 to understand the wildcard matching algorithm (RFC 1034). 3540 This option 3541 affects master zones. The default (<span><strong class="command">yes</strong></span>) is to check 3542 for non-terminal wildcards and issue a warning. 3543 </p></dd> 3544<dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt> 3545<dd><p> 3546 Perform post load zone integrity checks on master 3547 zones. This checks that MX and SRV records refer 3548 to address (A or AAAA) records and that glue 3549 address records exist for delegated zones. For 3550 MX and SRV records only in-zone hostnames are 3551 checked (for out-of-zone hostnames use 3552 <span><strong class="command">named-checkzone</strong></span>). 3553 For NS records only names below top of zone are 3554 checked (for out-of-zone names and glue consistency 3555 checks use <span><strong class="command">named-checkzone</strong></span>). 3556 The default is <span><strong class="command">yes</strong></span>. 3557 </p></dd> 3558<dt><span class="term"><span><strong class="command">check-mx-cname</strong></span></span></dt> 3559<dd><p> 3560 If <span><strong class="command">check-integrity</strong></span> is set then 3561 fail, warn or ignore MX records that refer 3562 to CNAMES. The default is to <span><strong class="command">warn</strong></span>. 3563 </p></dd> 3564<dt><span class="term"><span><strong class="command">check-srv-cname</strong></span></span></dt> 3565<dd><p> 3566 If <span><strong class="command">check-integrity</strong></span> is set then 3567 fail, warn or ignore SRV records that refer 3568 to CNAMES. The default is to <span><strong class="command">warn</strong></span>. 3569 </p></dd> 3570<dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt> 3571<dd><p> 3572 When performing integrity checks, also check that 3573 sibling glue exists. The default is <span><strong class="command">yes</strong></span>. 3574 </p></dd> 3575<dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt> 3576<dd><p> 3577 When returning authoritative negative responses to 3578 SOA queries set the TTL of the SOA record returned in 3579 the authority section to zero. 3580 The default is <span><strong class="command">yes</strong></span>. 3581 </p></dd> 3582<dt><span class="term"><span><strong class="command">zero-no-soa-ttl-cache</strong></span></span></dt> 3583<dd><p> 3584 When caching a negative response to a SOA query 3585 set the TTL to zero. 3586 The default is <span><strong class="command">no</strong></span>. 3587 </p></dd> 3588<dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt> 3589<dd> 3590<p> 3591 When set to the default value of <code class="literal">yes</code>, 3592 check the KSK bit in each key to determine how the key 3593 should be used when generating RRSIGs for a secure zone. 3594 </p> 3595<p> 3596 Ordinarily, zone-signing keys (that is, keys without the 3597 KSK bit set) are used to sign the entire zone, while 3598 key-signing keys (keys with the KSK bit set) are only 3599 used to sign the DNSKEY RRset at the zone apex. 3600 However, if this option is set to <code class="literal">no</code>, 3601 then the KSK bit is ignored; KSKs are treated as if they 3602 were ZSKs and are used to sign the entire zone. This is 3603 similar to the <span><strong class="command">dnssec-signzone -z</strong></span> 3604 command line option. 3605 </p> 3606<p> 3607 When this option is set to <code class="literal">yes</code>, there 3608 must be at least two active keys for every algorithm 3609 represented in the DNSKEY RRset: at least one KSK and one 3610 ZSK per algorithm. If there is any algorithm for which 3611 this requirement is not met, this option will be ignored 3612 for that algorithm. 3613 </p> 3614</dd> 3615<dt><span class="term"><span><strong class="command">dnssec-dnskey-kskonly</strong></span></span></dt> 3616<dd> 3617<p> 3618 When this option and <span><strong class="command">update-check-ksk</strong></span> 3619 are both set to <code class="literal">yes</code>, only key-signing 3620 keys (that is, keys with the KSK bit set) will be used 3621 to sign the DNSKEY RRset at the zone apex. Zone-signing 3622 keys (keys without the KSK bit set) will be used to sign 3623 the remainder of the zone, but not the DNSKEY RRset. 3624 This is similar to the 3625 <span><strong class="command">dnssec-signzone -x</strong></span> command line option. 3626 </p> 3627<p> 3628 The default is <span><strong class="command">no</strong></span>. If 3629 <span><strong class="command">update-check-ksk</strong></span> is set to 3630 <code class="literal">no</code>, this option is ignored. 3631 </p> 3632</dd> 3633<dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt> 3634<dd><p> 3635 Try to refresh the zone using TCP if UDP queries fail. 3636 For BIND 8 compatibility, the default is 3637 <span><strong class="command">yes</strong></span>. 3638 </p></dd> 3639<dt><span class="term"><span><strong class="command">dnssec-secure-to-insecure</strong></span></span></dt> 3640<dd> 3641<p> 3642 Allow a dynamic zone to transition from secure to 3643 insecure (i.e., signed to unsigned) by deleting all 3644 of the DNSKEY records. The default is <span><strong class="command">no</strong></span>. 3645 If set to <span><strong class="command">yes</strong></span>, and if the DNSKEY RRset 3646 at the zone apex is deleted, all RRSIG and NSEC records 3647 will be removed from the zone as well. 3648 </p> 3649<p> 3650 If the zone uses NSEC3, then it is also necessary to 3651 delete the NSEC3PARAM RRset from the zone apex; this will 3652 cause the removal of all corresponding NSEC3 records. 3653 (It is expected that this requirement will be eliminated 3654 in a future release.) 3655 </p> 3656<p> 3657 Note that if a zone has been configured with 3658 <span><strong class="command">auto-dnssec maintain</strong></span> and the 3659 private keys remain accessible in the key repository, 3660 then the zone will be automatically signed again the 3661 next time <span><strong class="command">named</strong></span> is started. 3662 </p> 3663</dd> 3664</dl></div> 3665</div> 3666<div class="sect3" lang="en"> 3667<div class="titlepage"><div><div><h4 class="title"> 3668<a name="id2583643"></a>Forwarding</h4></div></div></div> 3669<p> 3670 The forwarding facility can be used to create a large site-wide 3671 cache on a few servers, reducing traffic over links to external 3672 name servers. It can also be used to allow queries by servers that 3673 do not have direct access to the Internet, but wish to look up 3674 exterior 3675 names anyway. Forwarding occurs only on those queries for which 3676 the server is not authoritative and does not have the answer in 3677 its cache. 3678 </p> 3679<div class="variablelist"><dl> 3680<dt><span class="term"><span><strong class="command">forward</strong></span></span></dt> 3681<dd><p> 3682 This option is only meaningful if the 3683 forwarders list is not empty. A value of <code class="varname">first</code>, 3684 the default, causes the server to query the forwarders 3685 first — and 3686 if that doesn't answer the question, the server will then 3687 look for 3688 the answer itself. If <code class="varname">only</code> is 3689 specified, the 3690 server will only query the forwarders. 3691 </p></dd> 3692<dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt> 3693<dd><p> 3694 Specifies the IP addresses to be used 3695 for forwarding. The default is the empty list (no 3696 forwarding). 3697 </p></dd> 3698</dl></div> 3699<p> 3700 Forwarding can also be configured on a per-domain basis, allowing 3701 for the global forwarding options to be overridden in a variety 3702 of ways. You can set particular domains to use different 3703 forwarders, 3704 or have a different <span><strong class="command">forward only/first</strong></span> behavior, 3705 or not forward at all, see <a href="Bv9ARM.ch06.html#zone_statement_grammar" title="zone 3706 Statement Grammar">the section called “<span><strong class="command">zone</strong></span> 3707 Statement Grammar”</a>. 3708 </p> 3709</div> 3710<div class="sect3" lang="en"> 3711<div class="titlepage"><div><div><h4 class="title"> 3712<a name="id2583702"></a>Dual-stack Servers</h4></div></div></div> 3713<p> 3714 Dual-stack servers are used as servers of last resort to work 3715 around 3716 problems in reachability due the lack of support for either IPv4 3717 or IPv6 3718 on the host machine. 3719 </p> 3720<div class="variablelist"><dl> 3721<dt><span class="term"><span><strong class="command">dual-stack-servers</strong></span></span></dt> 3722<dd><p> 3723 Specifies host names or addresses of machines with access to 3724 both IPv4 and IPv6 transports. If a hostname is used, the 3725 server must be able 3726 to resolve the name using only the transport it has. If the 3727 machine is dual 3728 stacked, then the <span><strong class="command">dual-stack-servers</strong></span> have no effect unless 3729 access to a transport has been disabled on the command line 3730 (e.g. <span><strong class="command">named -4</strong></span>). 3731 </p></dd> 3732</dl></div> 3733</div> 3734<div class="sect3" lang="en"> 3735<div class="titlepage"><div><div><h4 class="title"> 3736<a name="access_control"></a>Access Control</h4></div></div></div> 3737<p> 3738 Access to the server can be restricted based on the IP address 3739 of the requesting system. See <a href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called “Address Match Lists”</a> for 3740 details on how to specify IP address lists. 3741 </p> 3742<div class="variablelist"><dl> 3743<dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt> 3744<dd><p> 3745 Specifies which hosts are allowed to 3746 notify this server, a slave, of zone changes in addition 3747 to the zone masters. 3748 <span><strong class="command">allow-notify</strong></span> may also be 3749 specified in the 3750 <span><strong class="command">zone</strong></span> statement, in which case 3751 it overrides the 3752 <span><strong class="command">options allow-notify</strong></span> 3753 statement. It is only meaningful 3754 for a slave zone. If not specified, the default is to 3755 process notify messages 3756 only from a zone's master. 3757 </p></dd> 3758<dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt> 3759<dd> 3760<p> 3761 Specifies which hosts are allowed to ask ordinary 3762 DNS questions. <span><strong class="command">allow-query</strong></span> may 3763 also be specified in the <span><strong class="command">zone</strong></span> 3764 statement, in which case it overrides the 3765 <span><strong class="command">options allow-query</strong></span> statement. 3766 If not specified, the default is to allow queries 3767 from all hosts. 3768 </p> 3769<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 3770<h3 class="title">Note</h3> 3771<p> 3772 <span><strong class="command">allow-query-cache</strong></span> is now 3773 used to specify access to the cache. 3774 </p> 3775</div> 3776</dd> 3777<dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt> 3778<dd> 3779<p> 3780 Specifies which local addresses can accept ordinary 3781 DNS questions. This makes it possible, for instance, 3782 to allow queries on internal-facing interfaces but 3783 disallow them on external-facing ones, without 3784 necessarily knowing the internal network's addresses. 3785 </p> 3786<p> 3787 <span><strong class="command">allow-query-on</strong></span> may 3788 also be specified in the <span><strong class="command">zone</strong></span> 3789 statement, in which case it overrides the 3790 <span><strong class="command">options allow-query-on</strong></span> statement. 3791 </p> 3792<p> 3793 If not specified, the default is to allow queries 3794 on all addresses. 3795 </p> 3796<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 3797<h3 class="title">Note</h3> 3798<p> 3799 <span><strong class="command">allow-query-cache</strong></span> is 3800 used to specify access to the cache. 3801 </p> 3802</div> 3803</dd> 3804<dt><span class="term"><span><strong class="command">allow-query-cache</strong></span></span></dt> 3805<dd><p> 3806 Specifies which hosts are allowed to get answers 3807 from the cache. If <span><strong class="command">allow-query-cache</strong></span> 3808 is not set then <span><strong class="command">allow-recursion</strong></span> 3809 is used if set, otherwise <span><strong class="command">allow-query</strong></span> 3810 is used if set unless <span><strong class="command">recursion no;</strong></span> is 3811 set in which case <span><strong class="command">none;</strong></span> is used, 3812 otherwise the default (<span><strong class="command">localnets;</strong></span> 3813 <span><strong class="command">localhost;</strong></span>) is used. 3814 </p></dd> 3815<dt><span class="term"><span><strong class="command">allow-query-cache-on</strong></span></span></dt> 3816<dd><p> 3817 Specifies which local addresses can give answers 3818 from the cache. If not specified, the default is 3819 to allow cache queries on any address, 3820 <span><strong class="command">localnets</strong></span> and 3821 <span><strong class="command">localhost</strong></span>. 3822 </p></dd> 3823<dt><span class="term"><span><strong class="command">allow-recursion</strong></span></span></dt> 3824<dd><p> 3825 Specifies which hosts are allowed to make recursive 3826 queries through this server. If 3827 <span><strong class="command">allow-recursion</strong></span> is not set 3828 then <span><strong class="command">allow-query-cache</strong></span> is 3829 used if set, otherwise <span><strong class="command">allow-query</strong></span> 3830 is used if set, otherwise the default 3831 (<span><strong class="command">localnets;</strong></span> 3832 <span><strong class="command">localhost;</strong></span>) is used. 3833 </p></dd> 3834<dt><span class="term"><span><strong class="command">allow-recursion-on</strong></span></span></dt> 3835<dd><p> 3836 Specifies which local addresses can accept recursive 3837 queries. If not specified, the default is to allow 3838 recursive queries on all addresses. 3839 </p></dd> 3840<dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt> 3841<dd><p> 3842 Specifies which hosts are allowed to 3843 submit Dynamic DNS updates for master zones. The default is 3844 to deny 3845 updates from all hosts. Note that allowing updates based 3846 on the requestor's IP address is insecure; see 3847 <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called “Dynamic Update Security”</a> for details. 3848 </p></dd> 3849<dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt> 3850<dd> 3851<p> 3852 Specifies which hosts are allowed to 3853 submit Dynamic DNS updates to slave zones to be forwarded to 3854 the 3855 master. The default is <strong class="userinput"><code>{ none; }</code></strong>, 3856 which 3857 means that no update forwarding will be performed. To 3858 enable 3859 update forwarding, specify 3860 <strong class="userinput"><code>allow-update-forwarding { any; };</code></strong>. 3861 Specifying values other than <strong class="userinput"><code>{ none; }</code></strong> or 3862 <strong class="userinput"><code>{ any; }</code></strong> is usually 3863 counterproductive, since 3864 the responsibility for update access control should rest 3865 with the 3866 master server, not the slaves. 3867 </p> 3868<p> 3869 Note that enabling the update forwarding feature on a slave 3870 server 3871 may expose master servers relying on insecure IP address 3872 based 3873 access control to attacks; see <a href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called “Dynamic Update Security”</a> 3874 for more details. 3875 </p> 3876</dd> 3877<dt><span class="term"><span><strong class="command">allow-v6-synthesis</strong></span></span></dt> 3878<dd><p> 3879 This option was introduced for the smooth transition from 3880 AAAA 3881 to A6 and from "nibble labels" to binary labels. 3882 However, since both A6 and binary labels were then 3883 deprecated, 3884 this option was also deprecated. 3885 It is now ignored with some warning messages. 3886 </p></dd> 3887<dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt> 3888<dd><p> 3889 Specifies which hosts are allowed to 3890 receive zone transfers from the server. <span><strong class="command">allow-transfer</strong></span> may 3891 also be specified in the <span><strong class="command">zone</strong></span> 3892 statement, in which 3893 case it overrides the <span><strong class="command">options allow-transfer</strong></span> statement. 3894 If not specified, the default is to allow transfers to all 3895 hosts. 3896 </p></dd> 3897<dt><span class="term"><span><strong class="command">blackhole</strong></span></span></dt> 3898<dd><p> 3899 Specifies a list of addresses that the 3900 server will not accept queries from or use to resolve a 3901 query. Queries 3902 from these addresses will not be responded to. The default 3903 is <strong class="userinput"><code>none</code></strong>. 3904 </p></dd> 3905<dt><span class="term"><span><strong class="command">filter-aaaa</strong></span></span></dt> 3906<dd><p> 3907 Specifies a list of addresses to which 3908 <span><strong class="command">filter-aaaa-on-v4</strong></span> 3909 is applies. The default is <strong class="userinput"><code>any</code></strong>. 3910 </p></dd> 3911<dt><span class="term"><span><strong class="command">resolver-query-timeout</strong></span></span></dt> 3912<dd><p> 3913 The amount of time the resolver will spend attempting 3914 to resolve a recursive query before failing. The 3915 default is <code class="literal">10</code> and the maximum is 3916 <code class="literal">30</code>. Setting it to <code class="literal">0</code> 3917 will result in the default being used. 3918 </p></dd> 3919</dl></div> 3920</div> 3921<div class="sect3" lang="en"> 3922<div class="titlepage"><div><div><h4 class="title"> 3923<a name="id2584322"></a>Interfaces</h4></div></div></div> 3924<p> 3925 The interfaces and ports that the server will answer queries 3926 from may be specified using the <span><strong class="command">listen-on</strong></span> option. <span><strong class="command">listen-on</strong></span> takes 3927 an optional port and an <code class="varname">address_match_list</code>. 3928 The server will listen on all interfaces allowed by the address 3929 match list. If a port is not specified, port 53 will be used. 3930 </p> 3931<p> 3932 Multiple <span><strong class="command">listen-on</strong></span> statements are 3933 allowed. 3934 For example, 3935 </p> 3936<pre class="programlisting">listen-on { 5.6.7.8; }; 3937listen-on port 1234 { !1.2.3.4; 1.2/16; }; 3938</pre> 3939<p> 3940 will enable the name server on port 53 for the IP address 3941 5.6.7.8, and on port 1234 of an address on the machine in net 3942 1.2 that is not 1.2.3.4. 3943 </p> 3944<p> 3945 If no <span><strong class="command">listen-on</strong></span> is specified, the 3946 server will listen on port 53 on all IPv4 interfaces. 3947 </p> 3948<p> 3949 The <span><strong class="command">listen-on-v6</strong></span> option is used to 3950 specify the interfaces and the ports on which the server will 3951 listen 3952 for incoming queries sent using IPv6. 3953 </p> 3954<p> 3955 When </p> 3956<pre class="programlisting">{ any; }</pre> 3957<p> is 3958 specified 3959 as the <code class="varname">address_match_list</code> for the 3960 <span><strong class="command">listen-on-v6</strong></span> option, 3961 the server does not bind a separate socket to each IPv6 interface 3962 address as it does for IPv4 if the operating system has enough API 3963 support for IPv6 (specifically if it conforms to RFC 3493 and RFC 3964 3542). 3965 Instead, it listens on the IPv6 wildcard address. 3966 If the system only has incomplete API support for IPv6, however, 3967 the behavior is the same as that for IPv4. 3968 </p> 3969<p> 3970 A list of particular IPv6 addresses can also be specified, in 3971 which case 3972 the server listens on a separate socket for each specified 3973 address, 3974 regardless of whether the desired API is supported by the system. 3975 </p> 3976<p> 3977 Multiple <span><strong class="command">listen-on-v6</strong></span> options can 3978 be used. 3979 For example, 3980 </p> 3981<pre class="programlisting">listen-on-v6 { any; }; 3982listen-on-v6 port 1234 { !2001:db8::/32; any; }; 3983</pre> 3984<p> 3985 will enable the name server on port 53 for any IPv6 addresses 3986 (with a single wildcard socket), 3987 and on port 1234 of IPv6 addresses that is not in the prefix 3988 2001:db8::/32 (with separate sockets for each matched address.) 3989 </p> 3990<p> 3991 To make the server not listen on any IPv6 address, use 3992 </p> 3993<pre class="programlisting">listen-on-v6 { none; }; 3994</pre> 3995<p> 3996 If no <span><strong class="command">listen-on-v6</strong></span> option is 3997 specified, the server will not listen on any IPv6 address 3998 unless <span><strong class="command">-6</strong></span> is specified when <span><strong class="command">named</strong></span> is 3999 invoked. If <span><strong class="command">-6</strong></span> is specified then 4000 <span><strong class="command">named</strong></span> will listen on port 53 on all IPv6 interfaces by default. 4001 </p> 4002</div> 4003<div class="sect3" lang="en"> 4004<div class="titlepage"><div><div><h4 class="title"> 4005<a name="query_address"></a>Query Address</h4></div></div></div> 4006<p> 4007 If the server doesn't know the answer to a question, it will 4008 query other name servers. <span><strong class="command">query-source</strong></span> specifies 4009 the address and port used for such queries. For queries sent over 4010 IPv6, there is a separate <span><strong class="command">query-source-v6</strong></span> option. 4011 If <span><strong class="command">address</strong></span> is <span><strong class="command">*</strong></span> (asterisk) or is omitted, 4012 a wildcard IP address (<span><strong class="command">INADDR_ANY</strong></span>) 4013 will be used. 4014 </p> 4015<p> 4016 If <span><strong class="command">port</strong></span> is <span><strong class="command">*</strong></span> or is omitted, 4017 a random port number from a pre-configured 4018 range is picked up and will be used for each query. 4019 The port range(s) is that specified in 4020 the <span><strong class="command">use-v4-udp-ports</strong></span> (for IPv4) 4021 and <span><strong class="command">use-v6-udp-ports</strong></span> (for IPv6) 4022 options, excluding the ranges specified in 4023 the <span><strong class="command">avoid-v4-udp-ports</strong></span> 4024 and <span><strong class="command">avoid-v6-udp-ports</strong></span> options, respectively. 4025 </p> 4026<p> 4027 The defaults of the <span><strong class="command">query-source</strong></span> and 4028 <span><strong class="command">query-source-v6</strong></span> options 4029 are: 4030 </p> 4031<pre class="programlisting">query-source address * port *; 4032query-source-v6 address * port *; 4033</pre> 4034<p> 4035 If <span><strong class="command">use-v4-udp-ports</strong></span> or 4036 <span><strong class="command">use-v6-udp-ports</strong></span> is unspecified, 4037 <span><strong class="command">named</strong></span> will check if the operating 4038 system provides a programming interface to retrieve the 4039 system's default range for ephemeral ports. 4040 If such an interface is available, 4041 <span><strong class="command">named</strong></span> will use the corresponding system 4042 default range; otherwise, it will use its own defaults: 4043 </p> 4044<pre class="programlisting">use-v4-udp-ports { range 1024 65535; }; 4045use-v6-udp-ports { range 1024 65535; }; 4046</pre> 4047<p> 4048 Note: make sure the ranges be sufficiently large for 4049 security. A desirable size depends on various parameters, 4050 but we generally recommend it contain at least 16384 ports 4051 (14 bits of entropy). 4052 Note also that the system's default range when used may be 4053 too small for this purpose, and that the range may even be 4054 changed while <span><strong class="command">named</strong></span> is running; the new 4055 range will automatically be applied when <span><strong class="command">named</strong></span> 4056 is reloaded. 4057 It is encouraged to 4058 configure <span><strong class="command">use-v4-udp-ports</strong></span> and 4059 <span><strong class="command">use-v6-udp-ports</strong></span> explicitly so that the 4060 ranges are sufficiently large and are reasonably 4061 independent from the ranges used by other applications. 4062 </p> 4063<p> 4064 Note: the operational configuration 4065 where <span><strong class="command">named</strong></span> runs may prohibit the use 4066 of some ports. For example, UNIX systems will not allow 4067 <span><strong class="command">named</strong></span> running without a root privilege 4068 to use ports less than 1024. 4069 If such ports are included in the specified (or detected) 4070 set of query ports, the corresponding query attempts will 4071 fail, resulting in resolution failures or delay. 4072 It is therefore important to configure the set of ports 4073 that can be safely used in the expected operational environment. 4074 </p> 4075<p> 4076 The defaults of the <span><strong class="command">avoid-v4-udp-ports</strong></span> and 4077 <span><strong class="command">avoid-v6-udp-ports</strong></span> options 4078 are: 4079 </p> 4080<pre class="programlisting">avoid-v4-udp-ports {}; 4081avoid-v6-udp-ports {}; 4082</pre> 4083<p> 4084 Note: BIND 9.5.0 introduced 4085 the <span><strong class="command">use-queryport-pool</strong></span> 4086 option to support a pool of such random ports, but this 4087 option is now obsolete because reusing the same ports in 4088 the pool may not be sufficiently secure. 4089 For the same reason, it is generally strongly discouraged to 4090 specify a particular port for the 4091 <span><strong class="command">query-source</strong></span> or 4092 <span><strong class="command">query-source-v6</strong></span> options; 4093 it implicitly disables the use of randomized port numbers. 4094 </p> 4095<div class="variablelist"><dl> 4096<dt><span class="term"><span><strong class="command">use-queryport-pool</strong></span></span></dt> 4097<dd><p> 4098 This option is obsolete. 4099 </p></dd> 4100<dt><span class="term"><span><strong class="command">queryport-pool-ports</strong></span></span></dt> 4101<dd><p> 4102 This option is obsolete. 4103 </p></dd> 4104<dt><span class="term"><span><strong class="command">queryport-pool-updateinterval</strong></span></span></dt> 4105<dd><p> 4106 This option is obsolete. 4107 </p></dd> 4108</dl></div> 4109<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 4110<h3 class="title">Note</h3> 4111<p> 4112 The address specified in the <span><strong class="command">query-source</strong></span> option 4113 is used for both UDP and TCP queries, but the port applies only 4114 to UDP queries. TCP queries always use a random 4115 unprivileged port. 4116 </p> 4117</div> 4118<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 4119<h3 class="title">Note</h3> 4120<p> 4121 Solaris 2.5.1 and earlier does not support setting the source 4122 address for TCP sockets. 4123 </p> 4124</div> 4125<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 4126<h3 class="title">Note</h3> 4127<p> 4128 See also <span><strong class="command">transfer-source</strong></span> and 4129 <span><strong class="command">notify-source</strong></span>. 4130 </p> 4131</div> 4132</div> 4133<div class="sect3" lang="en"> 4134<div class="titlepage"><div><div><h4 class="title"> 4135<a name="zone_transfers"></a>Zone Transfers</h4></div></div></div> 4136<p> 4137 <acronym class="acronym">BIND</acronym> has mechanisms in place to 4138 facilitate zone transfers 4139 and set limits on the amount of load that transfers place on the 4140 system. The following options apply to zone transfers. 4141 </p> 4142<div class="variablelist"><dl> 4143<dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt> 4144<dd><p> 4145 Defines a global list of IP addresses of name servers 4146 that are also sent NOTIFY messages whenever a fresh copy of 4147 the 4148 zone is loaded, in addition to the servers listed in the 4149 zone's NS records. 4150 This helps to ensure that copies of the zones will 4151 quickly converge on stealth servers. 4152 Optionally, a port may be specified with each 4153 <span><strong class="command">also-notify</strong></span> address to send 4154 the notify messages to a port other than the 4155 default of 53. 4156 If an <span><strong class="command">also-notify</strong></span> list 4157 is given in a <span><strong class="command">zone</strong></span> statement, 4158 it will override 4159 the <span><strong class="command">options also-notify</strong></span> 4160 statement. When a <span><strong class="command">zone notify</strong></span> 4161 statement 4162 is set to <span><strong class="command">no</strong></span>, the IP 4163 addresses in the global <span><strong class="command">also-notify</strong></span> list will 4164 not be sent NOTIFY messages for that zone. The default is 4165 the empty 4166 list (no global notification list). 4167 </p></dd> 4168<dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt> 4169<dd><p> 4170 Inbound zone transfers running longer than 4171 this many minutes will be terminated. The default is 120 4172 minutes 4173 (2 hours). The maximum value is 28 days (40320 minutes). 4174 </p></dd> 4175<dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt> 4176<dd><p> 4177 Inbound zone transfers making no progress 4178 in this many minutes will be terminated. The default is 60 4179 minutes 4180 (1 hour). The maximum value is 28 days (40320 minutes). 4181 </p></dd> 4182<dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt> 4183<dd><p> 4184 Outbound zone transfers running longer than 4185 this many minutes will be terminated. The default is 120 4186 minutes 4187 (2 hours). The maximum value is 28 days (40320 minutes). 4188 </p></dd> 4189<dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt> 4190<dd><p> 4191 Outbound zone transfers making no progress 4192 in this many minutes will be terminated. The default is 60 4193 minutes (1 4194 hour). The maximum value is 28 days (40320 minutes). 4195 </p></dd> 4196<dt><span class="term"><span><strong class="command">serial-query-rate</strong></span></span></dt> 4197<dd> 4198<p> 4199 Slave servers will periodically query master 4200 servers to find out if zone serial numbers have 4201 changed. Each such query uses a minute amount of 4202 the slave server's network bandwidth. To limit 4203 the amount of bandwidth used, BIND 9 limits the 4204 rate at which queries are sent. The value of the 4205 <span><strong class="command">serial-query-rate</strong></span> option, an 4206 integer, is the maximum number of queries sent 4207 per second. The default is 20. 4208 </p> 4209<p> 4210 In addition to controlling the rate SOA refresh 4211 queries are issued at 4212 <span><strong class="command">serial-query-rate</strong></span> also controls 4213 the rate at which NOTIFY messages are sent from 4214 both master and slave zones. 4215 </p> 4216</dd> 4217<dt><span class="term"><span><strong class="command">serial-queries</strong></span></span></dt> 4218<dd><p> 4219 In BIND 8, the <span><strong class="command">serial-queries</strong></span> 4220 option 4221 set the maximum number of concurrent serial number queries 4222 allowed to be outstanding at any given time. 4223 BIND 9 does not limit the number of outstanding 4224 serial queries and ignores the <span><strong class="command">serial-queries</strong></span> option. 4225 Instead, it limits the rate at which the queries are sent 4226 as defined using the <span><strong class="command">serial-query-rate</strong></span> option. 4227 </p></dd> 4228<dt><span class="term"><span><strong class="command">transfer-format</strong></span></span></dt> 4229<dd><p> 4230 Zone transfers can be sent using two different formats, 4231 <span><strong class="command">one-answer</strong></span> and 4232 <span><strong class="command">many-answers</strong></span>. 4233 The <span><strong class="command">transfer-format</strong></span> option is used 4234 on the master server to determine which format it sends. 4235 <span><strong class="command">one-answer</strong></span> uses one DNS message per 4236 resource record transferred. 4237 <span><strong class="command">many-answers</strong></span> packs as many resource 4238 records as possible into a message. 4239 <span><strong class="command">many-answers</strong></span> is more efficient, but is 4240 only supported by relatively new slave servers, 4241 such as <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym> 4242 8.x and <acronym class="acronym">BIND</acronym> 4.9.5 onwards. 4243 The <span><strong class="command">many-answers</strong></span> format is also supported by 4244 recent Microsoft Windows nameservers. 4245 The default is <span><strong class="command">many-answers</strong></span>. 4246 <span><strong class="command">transfer-format</strong></span> may be overridden on a 4247 per-server basis by using the <span><strong class="command">server</strong></span> 4248 statement. 4249 </p></dd> 4250<dt><span class="term"><span><strong class="command">transfers-in</strong></span></span></dt> 4251<dd><p> 4252 The maximum number of inbound zone transfers 4253 that can be running concurrently. The default value is <code class="literal">10</code>. 4254 Increasing <span><strong class="command">transfers-in</strong></span> may 4255 speed up the convergence 4256 of slave zones, but it also may increase the load on the 4257 local system. 4258 </p></dd> 4259<dt><span class="term"><span><strong class="command">transfers-out</strong></span></span></dt> 4260<dd><p> 4261 The maximum number of outbound zone transfers 4262 that can be running concurrently. Zone transfer requests in 4263 excess 4264 of the limit will be refused. The default value is <code class="literal">10</code>. 4265 </p></dd> 4266<dt><span class="term"><span><strong class="command">transfers-per-ns</strong></span></span></dt> 4267<dd><p> 4268 The maximum number of inbound zone transfers 4269 that can be concurrently transferring from a given remote 4270 name server. 4271 The default value is <code class="literal">2</code>. 4272 Increasing <span><strong class="command">transfers-per-ns</strong></span> 4273 may 4274 speed up the convergence of slave zones, but it also may 4275 increase 4276 the load on the remote name server. <span><strong class="command">transfers-per-ns</strong></span> may 4277 be overridden on a per-server basis by using the <span><strong class="command">transfers</strong></span> phrase 4278 of the <span><strong class="command">server</strong></span> statement. 4279 </p></dd> 4280<dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt> 4281<dd> 4282<p><span><strong class="command">transfer-source</strong></span> 4283 determines which local address will be bound to IPv4 4284 TCP connections used to fetch zones transferred 4285 inbound by the server. It also determines the 4286 source IPv4 address, and optionally the UDP port, 4287 used for the refresh queries and forwarded dynamic 4288 updates. If not set, it defaults to a system 4289 controlled value which will usually be the address 4290 of the interface "closest to" the remote end. This 4291 address must appear in the remote end's 4292 <span><strong class="command">allow-transfer</strong></span> option for the 4293 zone being transferred, if one is specified. This 4294 statement sets the 4295 <span><strong class="command">transfer-source</strong></span> for all zones, 4296 but can be overridden on a per-view or per-zone 4297 basis by including a 4298 <span><strong class="command">transfer-source</strong></span> statement within 4299 the <span><strong class="command">view</strong></span> or 4300 <span><strong class="command">zone</strong></span> block in the configuration 4301 file. 4302 </p> 4303<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 4304<h3 class="title">Note</h3> 4305<p> 4306 Solaris 2.5.1 and earlier does not support setting the 4307 source address for TCP sockets. 4308 </p> 4309</div> 4310</dd> 4311<dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt> 4312<dd><p> 4313 The same as <span><strong class="command">transfer-source</strong></span>, 4314 except zone transfers are performed using IPv6. 4315 </p></dd> 4316<dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt> 4317<dd> 4318<p> 4319 An alternate transfer source if the one listed in 4320 <span><strong class="command">transfer-source</strong></span> fails and 4321 <span><strong class="command">use-alt-transfer-source</strong></span> is 4322 set. 4323 </p> 4324<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 4325<h3 class="title">Note</h3> 4326 If you do not wish the alternate transfer source 4327 to be used, you should set 4328 <span><strong class="command">use-alt-transfer-source</strong></span> 4329 appropriately and you should not depend upon 4330 getting an answer back to the first refresh 4331 query. 4332 </div> 4333</dd> 4334<dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt> 4335<dd><p> 4336 An alternate transfer source if the one listed in 4337 <span><strong class="command">transfer-source-v6</strong></span> fails and 4338 <span><strong class="command">use-alt-transfer-source</strong></span> is 4339 set. 4340 </p></dd> 4341<dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt> 4342<dd><p> 4343 Use the alternate transfer sources or not. If views are 4344 specified this defaults to <span><strong class="command">no</strong></span> 4345 otherwise it defaults to 4346 <span><strong class="command">yes</strong></span> (for BIND 8 4347 compatibility). 4348 </p></dd> 4349<dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt> 4350<dd> 4351<p><span><strong class="command">notify-source</strong></span> 4352 determines which local source address, and 4353 optionally UDP port, will be used to send NOTIFY 4354 messages. This address must appear in the slave 4355 server's <span><strong class="command">masters</strong></span> zone clause or 4356 in an <span><strong class="command">allow-notify</strong></span> clause. This 4357 statement sets the <span><strong class="command">notify-source</strong></span> 4358 for all zones, but can be overridden on a per-zone or 4359 per-view basis by including a 4360 <span><strong class="command">notify-source</strong></span> statement within 4361 the <span><strong class="command">zone</strong></span> or 4362 <span><strong class="command">view</strong></span> block in the configuration 4363 file. 4364 </p> 4365<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 4366<h3 class="title">Note</h3> 4367<p> 4368 Solaris 2.5.1 and earlier does not support setting the 4369 source address for TCP sockets. 4370 </p> 4371</div> 4372</dd> 4373<dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt> 4374<dd><p> 4375 Like <span><strong class="command">notify-source</strong></span>, 4376 but applies to notify messages sent to IPv6 addresses. 4377 </p></dd> 4378</dl></div> 4379</div> 4380<div class="sect3" lang="en"> 4381<div class="titlepage"><div><div><h4 class="title"> 4382<a name="id2585531"></a>UDP Port Lists</h4></div></div></div> 4383<p> 4384 <span><strong class="command">use-v4-udp-ports</strong></span>, 4385 <span><strong class="command">avoid-v4-udp-ports</strong></span>, 4386 <span><strong class="command">use-v6-udp-ports</strong></span>, and 4387 <span><strong class="command">avoid-v6-udp-ports</strong></span> 4388 specify a list of IPv4 and IPv6 UDP ports that will be 4389 used or not used as source ports for UDP messages. 4390 See <a href="Bv9ARM.ch06.html#query_address" title="Query Address">the section called “Query Address”</a> about how the 4391 available ports are determined. 4392 For example, with the following configuration 4393 </p> 4394<pre class="programlisting"> 4395use-v6-udp-ports { range 32768 65535; }; 4396avoid-v6-udp-ports { 40000; range 50000 60000; }; 4397</pre> 4398<p> 4399 UDP ports of IPv6 messages sent 4400 from <span><strong class="command">named</strong></span> will be in one 4401 of the following ranges: 32768 to 39999, 40001 to 49999, 4402 and 60001 to 65535. 4403 </p> 4404<p> 4405 <span><strong class="command">avoid-v4-udp-ports</strong></span> and 4406 <span><strong class="command">avoid-v6-udp-ports</strong></span> can be used 4407 to prevent <span><strong class="command">named</strong></span> from choosing as its random source port a 4408 port that is blocked by your firewall or a port that is 4409 used by other applications; 4410 if a query went out with a source port blocked by a 4411 firewall, the 4412 answer would not get by the firewall and the name server would 4413 have to query again. 4414 Note: the desired range can also be represented only with 4415 <span><strong class="command">use-v4-udp-ports</strong></span> and 4416 <span><strong class="command">use-v6-udp-ports</strong></span>, and the 4417 <span><strong class="command">avoid-</strong></span> options are redundant in that 4418 sense; they are provided for backward compatibility and 4419 to possibly simplify the port specification. 4420 </p> 4421</div> 4422<div class="sect3" lang="en"> 4423<div class="titlepage"><div><div><h4 class="title"> 4424<a name="id2585591"></a>Operating System Resource Limits</h4></div></div></div> 4425<p> 4426 The server's usage of many system resources can be limited. 4427 Scaled values are allowed when specifying resource limits. For 4428 example, <span><strong class="command">1G</strong></span> can be used instead of 4429 <span><strong class="command">1073741824</strong></span> to specify a limit of 4430 one 4431 gigabyte. <span><strong class="command">unlimited</strong></span> requests 4432 unlimited use, or the 4433 maximum available amount. <span><strong class="command">default</strong></span> 4434 uses the limit 4435 that was in force when the server was started. See the description 4436 of <span><strong class="command">size_spec</strong></span> in <a href="Bv9ARM.ch06.html#configuration_file_elements" title="Configuration File Elements">the section called “Configuration File Elements”</a>. 4437 </p> 4438<p> 4439 The following options set operating system resource limits for 4440 the name server process. Some operating systems don't support 4441 some or 4442 any of the limits. On such systems, a warning will be issued if 4443 the 4444 unsupported limit is used. 4445 </p> 4446<div class="variablelist"><dl> 4447<dt><span class="term"><span><strong class="command">coresize</strong></span></span></dt> 4448<dd><p> 4449 The maximum size of a core dump. The default 4450 is <code class="literal">default</code>. 4451 </p></dd> 4452<dt><span class="term"><span><strong class="command">datasize</strong></span></span></dt> 4453<dd><p> 4454 The maximum amount of data memory the server 4455 may use. The default is <code class="literal">default</code>. 4456 This is a hard limit on server memory usage. 4457 If the server attempts to allocate memory in excess of this 4458 limit, the allocation will fail, which may in turn leave 4459 the server unable to perform DNS service. Therefore, 4460 this option is rarely useful as a way of limiting the 4461 amount of memory used by the server, but it can be used 4462 to raise an operating system data size limit that is 4463 too small by default. If you wish to limit the amount 4464 of memory used by the server, use the 4465 <span><strong class="command">max-cache-size</strong></span> and 4466 <span><strong class="command">recursive-clients</strong></span> 4467 options instead. 4468 </p></dd> 4469<dt><span class="term"><span><strong class="command">files</strong></span></span></dt> 4470<dd><p> 4471 The maximum number of files the server 4472 may have open concurrently. The default is <code class="literal">unlimited</code>. 4473 </p></dd> 4474<dt><span class="term"><span><strong class="command">stacksize</strong></span></span></dt> 4475<dd><p> 4476 The maximum amount of stack memory the server 4477 may use. The default is <code class="literal">default</code>. 4478 </p></dd> 4479</dl></div> 4480</div> 4481<div class="sect3" lang="en"> 4482<div class="titlepage"><div><div><h4 class="title"> 4483<a name="server_resource_limits"></a>Server Resource Limits</h4></div></div></div> 4484<p> 4485 The following options set limits on the server's 4486 resource consumption that are enforced internally by the 4487 server rather than the operating system. 4488 </p> 4489<div class="variablelist"><dl> 4490<dt><span class="term"><span><strong class="command">max-ixfr-log-size</strong></span></span></dt> 4491<dd><p> 4492 This option is obsolete; it is accepted 4493 and ignored for BIND 8 compatibility. The option 4494 <span><strong class="command">max-journal-size</strong></span> performs a 4495 similar function in BIND 9. 4496 </p></dd> 4497<dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt> 4498<dd><p> 4499 Sets a maximum size for each journal file 4500 (see <a href="Bv9ARM.ch04.html#journal" title="The journal file">the section called “The journal file”</a>). When the journal file 4501 approaches 4502 the specified size, some of the oldest transactions in the 4503 journal 4504 will be automatically removed. The default is 4505 <code class="literal">unlimited</code>. 4506 This may also be set on a per-zone basis. 4507 </p></dd> 4508<dt><span class="term"><span><strong class="command">host-statistics-max</strong></span></span></dt> 4509<dd><p> 4510 In BIND 8, specifies the maximum number of host statistics 4511 entries to be kept. 4512 Not implemented in BIND 9. 4513 </p></dd> 4514<dt><span class="term"><span><strong class="command">recursive-clients</strong></span></span></dt> 4515<dd><p> 4516 The maximum number of simultaneous recursive lookups 4517 the server will perform on behalf of clients. The default 4518 is 4519 <code class="literal">1000</code>. Because each recursing 4520 client uses a fair 4521 bit of memory, on the order of 20 kilobytes, the value of 4522 the 4523 <span><strong class="command">recursive-clients</strong></span> option may 4524 have to be decreased 4525 on hosts with limited memory. 4526 </p></dd> 4527<dt><span class="term"><span><strong class="command">tcp-clients</strong></span></span></dt> 4528<dd><p> 4529 The maximum number of simultaneous client TCP 4530 connections that the server will accept. 4531 The default is <code class="literal">100</code>. 4532 </p></dd> 4533<dt><span class="term"><span><strong class="command">reserved-sockets</strong></span></span></dt> 4534<dd> 4535<p> 4536 The number of file descriptors reserved for TCP, stdio, 4537 etc. This needs to be big enough to cover the number of 4538 interfaces <span><strong class="command">named</strong></span> listens on, <span><strong class="command">tcp-clients</strong></span> as well as 4539 to provide room for outgoing TCP queries and incoming zone 4540 transfers. The default is <code class="literal">512</code>. 4541 The minimum value is <code class="literal">128</code> and the 4542 maximum value is <code class="literal">128</code> less than 4543 maxsockets (-S). This option may be removed in the future. 4544 </p> 4545<p> 4546 This option has little effect on Windows. 4547 </p> 4548</dd> 4549<dt><span class="term"><span><strong class="command">max-cache-size</strong></span></span></dt> 4550<dd><p> 4551 The maximum amount of memory to use for the 4552 server's cache, in bytes. 4553 When the amount of data in the cache 4554 reaches this limit, the server will cause records to expire 4555 prematurely based on an LRU based strategy so that 4556 the limit is not exceeded. 4557 A value of 0 is special, meaning that 4558 records are purged from the cache only when their 4559 TTLs expire. 4560 Another special keyword <strong class="userinput"><code>unlimited</code></strong> 4561 means the maximum value of 32-bit unsigned integers 4562 (0xffffffff), which may not have the same effect as 4563 0 on machines that support more than 32 bits of 4564 memory space. 4565 Any positive values less than 2MB will be ignored reset 4566 to 2MB. 4567 In a server with multiple views, the limit applies 4568 separately to the cache of each view. 4569 The default is 0. 4570 </p></dd> 4571<dt><span class="term"><span><strong class="command">tcp-listen-queue</strong></span></span></dt> 4572<dd><p> 4573 The listen queue depth. The default and minimum is 3. 4574 If the kernel supports the accept filter "dataready" this 4575 also controls how 4576 many TCP connections that will be queued in kernel space 4577 waiting for 4578 some data before being passed to accept. Values less than 3 4579 will be 4580 silently raised. 4581 </p></dd> 4582</dl></div> 4583</div> 4584<div class="sect3" lang="en"> 4585<div class="titlepage"><div><div><h4 class="title"> 4586<a name="id2586082"></a>Periodic Task Intervals</h4></div></div></div> 4587<div class="variablelist"><dl> 4588<dt><span class="term"><span><strong class="command">cleaning-interval</strong></span></span></dt> 4589<dd><p> 4590 This interval is effectively obsolete. Previously, 4591 the server would remove expired resource records 4592 from the cache every <span><strong class="command">cleaning-interval</strong></span> minutes. 4593 <acronym class="acronym">BIND</acronym> 9 now manages cache 4594 memory in a more sophisticated manner and does not 4595 rely on the periodic cleaning any more. 4596 Specifying this option therefore has no effect on 4597 the server's behavior. 4598 </p></dd> 4599<dt><span class="term"><span><strong class="command">heartbeat-interval</strong></span></span></dt> 4600<dd><p> 4601 The server will perform zone maintenance tasks 4602 for all zones marked as <span><strong class="command">dialup</strong></span> whenever this 4603 interval expires. The default is 60 minutes. Reasonable 4604 values are up 4605 to 1 day (1440 minutes). The maximum value is 28 days 4606 (40320 minutes). 4607 If set to 0, no zone maintenance for these zones will occur. 4608 </p></dd> 4609<dt><span class="term"><span><strong class="command">interface-interval</strong></span></span></dt> 4610<dd><p> 4611 The server will scan the network interface list 4612 every <span><strong class="command">interface-interval</strong></span> 4613 minutes. The default 4614 is 60 minutes. The maximum value is 28 days (40320 minutes). 4615 If set to 0, interface scanning will only occur when 4616 the configuration file is loaded. After the scan, the 4617 server will 4618 begin listening for queries on any newly discovered 4619 interfaces (provided they are allowed by the 4620 <span><strong class="command">listen-on</strong></span> configuration), and 4621 will 4622 stop listening on interfaces that have gone away. 4623 </p></dd> 4624<dt><span class="term"><span><strong class="command">statistics-interval</strong></span></span></dt> 4625<dd> 4626<p> 4627 Name server statistics will be logged 4628 every <span><strong class="command">statistics-interval</strong></span> 4629 minutes. The default is 4630 60. The maximum value is 28 days (40320 minutes). 4631 If set to 0, no statistics will be logged. 4632 </p> 4633<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 4634<h3 class="title">Note</h3> 4635<p> 4636 Not yet implemented in 4637 <acronym class="acronym">BIND</acronym> 9. 4638 </p> 4639</div> 4640</dd> 4641</dl></div> 4642</div> 4643<div class="sect3" lang="en"> 4644<div class="titlepage"><div><div><h4 class="title"> 4645<a name="topology"></a>Topology</h4></div></div></div> 4646<p> 4647 All other things being equal, when the server chooses a name 4648 server 4649 to query from a list of name servers, it prefers the one that is 4650 topologically closest to itself. The <span><strong class="command">topology</strong></span> statement 4651 takes an <span><strong class="command">address_match_list</strong></span> and 4652 interprets it 4653 in a special way. Each top-level list element is assigned a 4654 distance. 4655 Non-negated elements get a distance based on their position in the 4656 list, where the closer the match is to the start of the list, the 4657 shorter the distance is between it and the server. A negated match 4658 will be assigned the maximum distance from the server. If there 4659 is no match, the address will get a distance which is further than 4660 any non-negated list element, and closer than any negated element. 4661 For example, 4662 </p> 4663<pre class="programlisting">topology { 4664 10/8; 4665 !1.2.3/24; 4666 { 1.2/16; 3/8; }; 4667};</pre> 4668<p> 4669 will prefer servers on network 10 the most, followed by hosts 4670 on network 1.2.0.0 (netmask 255.255.0.0) and network 3, with the 4671 exception of hosts on network 1.2.3 (netmask 255.255.255.0), which 4672 is preferred least of all. 4673 </p> 4674<p> 4675 The default topology is 4676 </p> 4677<pre class="programlisting"> topology { localhost; localnets; }; 4678</pre> 4679<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 4680<h3 class="title">Note</h3> 4681<p> 4682 The <span><strong class="command">topology</strong></span> option 4683 is not implemented in <acronym class="acronym">BIND</acronym> 9. 4684 </p> 4685</div> 4686</div> 4687<div class="sect3" lang="en"> 4688<div class="titlepage"><div><div><h4 class="title"> 4689<a name="the_sortlist_statement"></a>The <span><strong class="command">sortlist</strong></span> Statement</h4></div></div></div> 4690<p> 4691 The response to a DNS query may consist of multiple resource 4692 records (RRs) forming a resource records set (RRset). 4693 The name server will normally return the 4694 RRs within the RRset in an indeterminate order 4695 (but see the <span><strong class="command">rrset-order</strong></span> 4696 statement in <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called “RRset Ordering”</a>). 4697 The client resolver code should rearrange the RRs as appropriate, 4698 that is, using any addresses on the local net in preference to 4699 other addresses. 4700 However, not all resolvers can do this or are correctly 4701 configured. 4702 When a client is using a local server, the sorting can be performed 4703 in the server, based on the client's address. This only requires 4704 configuring the name servers, not all the clients. 4705 </p> 4706<p> 4707 The <span><strong class="command">sortlist</strong></span> statement (see below) 4708 takes 4709 an <span><strong class="command">address_match_list</strong></span> and 4710 interprets it even 4711 more specifically than the <span><strong class="command">topology</strong></span> 4712 statement 4713 does (<a href="Bv9ARM.ch06.html#topology" title="Topology">the section called “Topology”</a>). 4714 Each top level statement in the <span><strong class="command">sortlist</strong></span> must 4715 itself be an explicit <span><strong class="command">address_match_list</strong></span> with 4716 one or two elements. The first element (which may be an IP 4717 address, 4718 an IP prefix, an ACL name or a nested <span><strong class="command">address_match_list</strong></span>) 4719 of each top level list is checked against the source address of 4720 the query until a match is found. 4721 </p> 4722<p> 4723 Once the source address of the query has been matched, if 4724 the top level statement contains only one element, the actual 4725 primitive 4726 element that matched the source address is used to select the 4727 address 4728 in the response to move to the beginning of the response. If the 4729 statement is a list of two elements, then the second element is 4730 treated the same as the <span><strong class="command">address_match_list</strong></span> in 4731 a <span><strong class="command">topology</strong></span> statement. Each top 4732 level element 4733 is assigned a distance and the address in the response with the 4734 minimum 4735 distance is moved to the beginning of the response. 4736 </p> 4737<p> 4738 In the following example, any queries received from any of 4739 the addresses of the host itself will get responses preferring 4740 addresses 4741 on any of the locally connected networks. Next most preferred are 4742 addresses 4743 on the 192.168.1/24 network, and after that either the 4744 192.168.2/24 4745 or 4746 192.168.3/24 network with no preference shown between these two 4747 networks. Queries received from a host on the 192.168.1/24 network 4748 will prefer other addresses on that network to the 192.168.2/24 4749 and 4750 192.168.3/24 networks. Queries received from a host on the 4751 192.168.4/24 4752 or the 192.168.5/24 network will only prefer other addresses on 4753 their directly connected networks. 4754 </p> 4755<pre class="programlisting">sortlist { 4756 // IF the local host 4757 // THEN first fit on the following nets 4758 { localhost; 4759 { localnets; 4760 192.168.1/24; 4761 { 192.168.2/24; 192.168.3/24; }; }; }; 4762 // IF on class C 192.168.1 THEN use .1, or .2 or .3 4763 { 192.168.1/24; 4764 { 192.168.1/24; 4765 { 192.168.2/24; 192.168.3/24; }; }; }; 4766 // IF on class C 192.168.2 THEN use .2, or .1 or .3 4767 { 192.168.2/24; 4768 { 192.168.2/24; 4769 { 192.168.1/24; 192.168.3/24; }; }; }; 4770 // IF on class C 192.168.3 THEN use .3, or .1 or .2 4771 { 192.168.3/24; 4772 { 192.168.3/24; 4773 { 192.168.1/24; 192.168.2/24; }; }; }; 4774 // IF .4 or .5 THEN prefer that net 4775 { { 192.168.4/24; 192.168.5/24; }; 4776 }; 4777};</pre> 4778<p> 4779 The following example will give reasonable behavior for the 4780 local host and hosts on directly connected networks. It is similar 4781 to the behavior of the address sort in <acronym class="acronym">BIND</acronym> 4.9.x. Responses sent 4782 to queries from the local host will favor any of the directly 4783 connected 4784 networks. Responses sent to queries from any other hosts on a 4785 directly 4786 connected network will prefer addresses on that same network. 4787 Responses 4788 to other queries will not be sorted. 4789 </p> 4790<pre class="programlisting">sortlist { 4791 { localhost; localnets; }; 4792 { localnets; }; 4793}; 4794</pre> 4795</div> 4796<div class="sect3" lang="en"> 4797<div class="titlepage"><div><div><h4 class="title"> 4798<a name="rrset_ordering"></a>RRset Ordering</h4></div></div></div> 4799<p> 4800 When multiple records are returned in an answer it may be 4801 useful to configure the order of the records placed into the 4802 response. 4803 The <span><strong class="command">rrset-order</strong></span> statement permits 4804 configuration 4805 of the ordering of the records in a multiple record response. 4806 See also the <span><strong class="command">sortlist</strong></span> statement, 4807 <a href="Bv9ARM.ch06.html#the_sortlist_statement" title="The sortlist Statement">the section called “The <span><strong class="command">sortlist</strong></span> Statement”</a>. 4808 </p> 4809<p> 4810 An <span><strong class="command">order_spec</strong></span> is defined as 4811 follows: 4812 </p> 4813<p> 4814 [<span class="optional">class <em class="replaceable"><code>class_name</code></em></span>] 4815 [<span class="optional">type <em class="replaceable"><code>type_name</code></em></span>] 4816 [<span class="optional">name <em class="replaceable"><code>"domain_name"</code></em></span>] 4817 order <em class="replaceable"><code>ordering</code></em> 4818 </p> 4819<p> 4820 If no class is specified, the default is <span><strong class="command">ANY</strong></span>. 4821 If no type is specified, the default is <span><strong class="command">ANY</strong></span>. 4822 If no name is specified, the default is "<span><strong class="command">*</strong></span>" (asterisk). 4823 </p> 4824<p> 4825 The legal values for <span><strong class="command">ordering</strong></span> are: 4826 </p> 4827<div class="informaltable"><table border="1"> 4828<colgroup> 4829<col> 4830<col> 4831</colgroup> 4832<tbody> 4833<tr> 4834<td> 4835 <p><span><strong class="command">fixed</strong></span></p> 4836 </td> 4837<td> 4838 <p> 4839 Records are returned in the order they 4840 are defined in the zone file. 4841 </p> 4842 </td> 4843</tr> 4844<tr> 4845<td> 4846 <p><span><strong class="command">random</strong></span></p> 4847 </td> 4848<td> 4849 <p> 4850 Records are returned in some random order. 4851 </p> 4852 </td> 4853</tr> 4854<tr> 4855<td> 4856 <p><span><strong class="command">cyclic</strong></span></p> 4857 </td> 4858<td> 4859 <p> 4860 Records are returned in a cyclic round-robin order. 4861 </p> 4862 <p> 4863 If <acronym class="acronym">BIND</acronym> is configured with the 4864 "--enable-fixed-rrset" option at compile time, then 4865 the initial ordering of the RRset will match the 4866 one specified in the zone file. 4867 </p> 4868 </td> 4869</tr> 4870</tbody> 4871</table></div> 4872<p> 4873 For example: 4874 </p> 4875<pre class="programlisting">rrset-order { 4876 class IN type A name "host.example.com" order random; 4877 order cyclic; 4878}; 4879</pre> 4880<p> 4881 will cause any responses for type A records in class IN that 4882 have "<code class="literal">host.example.com</code>" as a 4883 suffix, to always be returned 4884 in random order. All other records are returned in cyclic order. 4885 </p> 4886<p> 4887 If multiple <span><strong class="command">rrset-order</strong></span> statements 4888 appear, 4889 they are not combined — the last one applies. 4890 </p> 4891<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 4892<h3 class="title">Note</h3> 4893<p> 4894 In this release of <acronym class="acronym">BIND</acronym> 9, the 4895 <span><strong class="command">rrset-order</strong></span> statement does not support 4896 "fixed" ordering by default. Fixed ordering can be enabled 4897 at compile time by specifying "--enable-fixed-rrset" on 4898 the "configure" command line. 4899 </p> 4900</div> 4901</div> 4902<div class="sect3" lang="en"> 4903<div class="titlepage"><div><div><h4 class="title"> 4904<a name="tuning"></a>Tuning</h4></div></div></div> 4905<div class="variablelist"><dl> 4906<dt><span class="term"><span><strong class="command">lame-ttl</strong></span></span></dt> 4907<dd> 4908<p> 4909 Sets the number of seconds to cache a 4910 lame server indication. 0 disables caching. (This is 4911 <span class="bold"><strong>NOT</strong></span> recommended.) 4912 The default is <code class="literal">600</code> (10 minutes) and the 4913 maximum value is 4914 <code class="literal">1800</code> (30 minutes). 4915 </p> 4916<p> 4917 Lame-ttl also controls the amount of time DNSSEC 4918 validation failures are cached. There is a minimum 4919 of 30 seconds applied to bad cache entries if the 4920 lame-ttl is set to less than 30 seconds. 4921 </p> 4922</dd> 4923<dt><span class="term"><span><strong class="command">max-ncache-ttl</strong></span></span></dt> 4924<dd><p> 4925 To reduce network traffic and increase performance, 4926 the server stores negative answers. <span><strong class="command">max-ncache-ttl</strong></span> is 4927 used to set a maximum retention time for these answers in 4928 the server 4929 in seconds. The default 4930 <span><strong class="command">max-ncache-ttl</strong></span> is <code class="literal">10800</code> seconds (3 hours). 4931 <span><strong class="command">max-ncache-ttl</strong></span> cannot exceed 4932 7 days and will 4933 be silently truncated to 7 days if set to a greater value. 4934 </p></dd> 4935<dt><span class="term"><span><strong class="command">max-cache-ttl</strong></span></span></dt> 4936<dd><p> 4937 Sets the maximum time for which the server will 4938 cache ordinary (positive) answers. The default is 4939 one week (7 days). 4940 A value of zero may cause all queries to return 4941 SERVFAIL, because of lost caches of intermediate 4942 RRsets (such as NS and glue AAAA/A records) in the 4943 resolution process. 4944 </p></dd> 4945<dt><span class="term"><span><strong class="command">min-roots</strong></span></span></dt> 4946<dd> 4947<p> 4948 The minimum number of root servers that 4949 is required for a request for the root servers to be 4950 accepted. The default 4951 is <strong class="userinput"><code>2</code></strong>. 4952 </p> 4953<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 4954<h3 class="title">Note</h3> 4955<p> 4956 Not implemented in <acronym class="acronym">BIND</acronym> 9. 4957 </p> 4958</div> 4959</dd> 4960<dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt> 4961<dd> 4962<p> 4963 Specifies the number of days into the future when 4964 DNSSEC signatures automatically generated as a 4965 result of dynamic updates (<a href="Bv9ARM.ch04.html#dynamic_update" title="Dynamic Update">the section called “Dynamic Update”</a>) will expire. There 4966 is an optional second field which specifies how 4967 long before expiry that the signatures will be 4968 regenerated. If not specified, the signatures will 4969 be regenerated at 1/4 of base interval. The second 4970 field is specified in days if the base interval is 4971 greater than 7 days otherwise it is specified in hours. 4972 The default base interval is <code class="literal">30</code> days 4973 giving a re-signing interval of 7 1/2 days. The maximum 4974 values are 10 years (3660 days). 4975 </p> 4976<p> 4977 The signature inception time is unconditionally 4978 set to one hour before the current time to allow 4979 for a limited amount of clock skew. 4980 </p> 4981<p> 4982 The <span><strong class="command">sig-validity-interval</strong></span> 4983 should be, at least, several multiples of the SOA 4984 expire interval to allow for reasonable interaction 4985 between the various timer and expiry dates. 4986 </p> 4987</dd> 4988<dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt> 4989<dd><p> 4990 Specify the maximum number of nodes to be 4991 examined in each quantum when signing a zone with 4992 a new DNSKEY. The default is 4993 <code class="literal">100</code>. 4994 </p></dd> 4995<dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt> 4996<dd><p> 4997 Specify a threshold number of signatures that 4998 will terminate processing a quantum when signing 4999 a zone with a new DNSKEY. The default is 5000 <code class="literal">10</code>. 5001 </p></dd> 5002<dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt> 5003<dd> 5004<p> 5005 Specify a private RDATA type to be used when generating 5006 key signing records. The default is 5007 <code class="literal">65534</code>. 5008 </p> 5009<p> 5010 It is expected that this parameter may be removed 5011 in a future version once there is a standard type. 5012 </p> 5013</dd> 5014<dt> 5015<span class="term"><span><strong class="command">min-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">max-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">min-retry-time</strong></span>, </span><span class="term"><span><strong class="command">max-retry-time</strong></span></span> 5016</dt> 5017<dd> 5018<p> 5019 These options control the server's behavior on refreshing a 5020 zone 5021 (querying for SOA changes) or retrying failed transfers. 5022 Usually the SOA values for the zone are used, but these 5023 values 5024 are set by the master, giving slave server administrators 5025 little 5026 control over their contents. 5027 </p> 5028<p> 5029 These options allow the administrator to set a minimum and 5030 maximum 5031 refresh and retry time either per-zone, per-view, or 5032 globally. 5033 These options are valid for slave and stub zones, 5034 and clamp the SOA refresh and retry times to the specified 5035 values. 5036 </p> 5037<p> 5038 The following defaults apply. 5039 <span><strong class="command">min-refresh-time</strong></span> 300 seconds, 5040 <span><strong class="command">max-refresh-time</strong></span> 2419200 seconds 5041 (4 weeks), <span><strong class="command">min-retry-time</strong></span> 500 seconds, 5042 and <span><strong class="command">max-retry-time</strong></span> 1209600 seconds 5043 (2 weeks). 5044 </p> 5045</dd> 5046<dt><span class="term"><span><strong class="command">edns-udp-size</strong></span></span></dt> 5047<dd> 5048<p> 5049 Sets the advertised EDNS UDP buffer size in bytes 5050 to control the size of packets received. 5051 Valid values are 512 to 4096 (values outside this range 5052 will be silently adjusted). The default value 5053 is 4096. The usual reason for setting 5054 <span><strong class="command">edns-udp-size</strong></span> to a non-default 5055 value is to get UDP answers to pass through broken 5056 firewalls that block fragmented packets and/or 5057 block UDP packets that are greater than 512 bytes. 5058 </p> 5059<p> 5060 <span><strong class="command">named</strong></span> will fallback to using 512 bytes 5061 if it get a series of timeout at the initial value. 512 5062 bytes is not being offered to encourage sites to fix their 5063 firewalls. Small EDNS UDP sizes will result in the 5064 excessive use of TCP. 5065 </p> 5066</dd> 5067<dt><span class="term"><span><strong class="command">max-udp-size</strong></span></span></dt> 5068<dd> 5069<p> 5070 Sets the maximum EDNS UDP message size 5071 <span><strong class="command">named</strong></span> will send in bytes. 5072 Valid values are 512 to 4096 (values outside this 5073 range will be silently adjusted). The default 5074 value is 4096. The usual reason for setting 5075 <span><strong class="command">max-udp-size</strong></span> to a non-default 5076 value is to get UDP answers to pass through broken 5077 firewalls that block fragmented packets and/or 5078 block UDP packets that are greater than 512 bytes. 5079 This is independent of the advertised receive 5080 buffer (<span><strong class="command">edns-udp-size</strong></span>). 5081 </p> 5082<p> 5083 Setting this to a low value will encourage additional 5084 TCP traffic to the nameserver. 5085 </p> 5086</dd> 5087<dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt> 5088<dd><p>Specifies 5089 the file format of zone files (see 5090 <a href="Bv9ARM.ch06.html#zonefile_format" title="Additional File Formats">the section called “Additional File Formats”</a>). 5091 The default value is <code class="constant">text</code>, which is the 5092 standard textual representation. Files in other formats 5093 than <code class="constant">text</code> are typically expected 5094 to be generated by the <span><strong class="command">named-compilezone</strong></span> tool. 5095 Note that when a zone file in a different format than 5096 <code class="constant">text</code> is loaded, <span><strong class="command">named</strong></span> 5097 may omit some of the checks which would be performed for a 5098 file in the <code class="constant">text</code> format. In particular, 5099 <span><strong class="command">check-names</strong></span> checks do not apply 5100 for the <code class="constant">raw</code> format. This means 5101 a zone file in the <code class="constant">raw</code> format 5102 must be generated with the same check level as that 5103 specified in the <span><strong class="command">named</strong></span> configuration 5104 file. This statement sets the 5105 <span><strong class="command">masterfile-format</strong></span> for all zones, 5106 but can be overridden on a per-zone or per-view basis 5107 by including a <span><strong class="command">masterfile-format</strong></span> 5108 statement within the <span><strong class="command">zone</strong></span> or 5109 <span><strong class="command">view</strong></span> block in the configuration 5110 file. 5111 </p></dd> 5112<dt> 5113<a name="clients-per-query"></a><span class="term"><span><strong class="command">clients-per-query</strong></span>, </span><span class="term"><span><strong class="command">max-clients-per-query</strong></span></span> 5114</dt> 5115<dd> 5116<p>These set the 5117 initial value (minimum) and maximum number of recursive 5118 simultaneous clients for any given query 5119 (<qname,qtype,qclass>) that the server will accept 5120 before dropping additional clients. <span><strong class="command">named</strong></span> will attempt to 5121 self tune this value and changes will be logged. The 5122 default values are 10 and 100. 5123 </p> 5124<p> 5125 This value should reflect how many queries come in for 5126 a given name in the time it takes to resolve that name. 5127 If the number of queries exceed this value, <span><strong class="command">named</strong></span> will 5128 assume that it is dealing with a non-responsive zone 5129 and will drop additional queries. If it gets a response 5130 after dropping queries, it will raise the estimate. The 5131 estimate will then be lowered in 20 minutes if it has 5132 remained unchanged. 5133 </p> 5134<p> 5135 If <span><strong class="command">clients-per-query</strong></span> is set to zero, 5136 then there is no limit on the number of clients per query 5137 and no queries will be dropped. 5138 </p> 5139<p> 5140 If <span><strong class="command">max-clients-per-query</strong></span> is set to zero, 5141 then there is no upper bound other than imposed by 5142 <span><strong class="command">recursive-clients</strong></span>. 5143 </p> 5144</dd> 5145<dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt> 5146<dd> 5147<p> 5148 The delay, in seconds, between sending sets of notify 5149 messages for a zone. The default is five (5) seconds. 5150 </p> 5151<p> 5152 The overall rate that NOTIFY messages are sent for all 5153 zones is controlled by <span><strong class="command">serial-query-rate</strong></span>. 5154 </p> 5155</dd> 5156</dl></div> 5157</div> 5158<div class="sect3" lang="en"> 5159<div class="titlepage"><div><div><h4 class="title"> 5160<a name="builtin"></a>Built-in server information zones</h4></div></div></div> 5161<p> 5162 The server provides some helpful diagnostic information 5163 through a number of built-in zones under the 5164 pseudo-top-level-domain <code class="literal">bind</code> in the 5165 <span><strong class="command">CHAOS</strong></span> class. These zones are part 5166 of a 5167 built-in view (see <a href="Bv9ARM.ch06.html#view_statement_grammar" title="view Statement Grammar">the section called “<span><strong class="command">view</strong></span> Statement Grammar”</a>) of 5168 class 5169 <span><strong class="command">CHAOS</strong></span> which is separate from the 5170 default view of 5171 class <span><strong class="command">IN</strong></span>; therefore, any global 5172 server options 5173 such as <span><strong class="command">allow-query</strong></span> do not apply 5174 the these zones. 5175 If you feel the need to disable these zones, use the options 5176 below, or hide the built-in <span><strong class="command">CHAOS</strong></span> 5177 view by 5178 defining an explicit view of class <span><strong class="command">CHAOS</strong></span> 5179 that matches all clients. 5180 </p> 5181<div class="variablelist"><dl> 5182<dt><span class="term"><span><strong class="command">version</strong></span></span></dt> 5183<dd><p> 5184 The version the server should report 5185 via a query of the name <code class="literal">version.bind</code> 5186 with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>. 5187 The default is the real version number of this server. 5188 Specifying <span><strong class="command">version none</strong></span> 5189 disables processing of the queries. 5190 </p></dd> 5191<dt><span class="term"><span><strong class="command">hostname</strong></span></span></dt> 5192<dd><p> 5193 The hostname the server should report via a query of 5194 the name <code class="filename">hostname.bind</code> 5195 with type <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>. 5196 This defaults to the hostname of the machine hosting the 5197 name server as 5198 found by the gethostname() function. The primary purpose of such queries 5199 is to 5200 identify which of a group of anycast servers is actually 5201 answering your queries. Specifying <span><strong class="command">hostname none;</strong></span> 5202 disables processing of the queries. 5203 </p></dd> 5204<dt><span class="term"><span><strong class="command">server-id</strong></span></span></dt> 5205<dd><p> 5206 The ID the server should report when receiving a Name 5207 Server Identifier (NSID) query, or a query of the name 5208 <code class="filename">ID.SERVER</code> with type 5209 <span><strong class="command">TXT</strong></span>, class <span><strong class="command">CHAOS</strong></span>. 5210 The primary purpose of such queries is to 5211 identify which of a group of anycast servers is actually 5212 answering your queries. Specifying <span><strong class="command">server-id none;</strong></span> 5213 disables processing of the queries. 5214 Specifying <span><strong class="command">server-id hostname;</strong></span> will cause <span><strong class="command">named</strong></span> to 5215 use the hostname as found by the gethostname() function. 5216 The default <span><strong class="command">server-id</strong></span> is <span><strong class="command">none</strong></span>. 5217 </p></dd> 5218</dl></div> 5219</div> 5220<div class="sect3" lang="en"> 5221<div class="titlepage"><div><div><h4 class="title"> 5222<a name="empty"></a>Built-in Empty Zones</h4></div></div></div> 5223<p> 5224 Named has some built-in empty zones (SOA and NS records only). 5225 These are for zones that should normally be answered locally 5226 and which queries should not be sent to the Internet's root 5227 servers. The official servers which cover these namespaces 5228 return NXDOMAIN responses to these queries. In particular, 5229 these cover the reverse namespaces for addresses from 5230 RFC 1918, RFC 4193, and RFC 5737. They also include the 5231 reverse namespace for IPv6 local address (locally assigned), 5232 IPv6 link local addresses, the IPv6 loopback address and the 5233 IPv6 unknown address. 5234 </p> 5235<p> 5236 Named will attempt to determine if a built-in zone already exists 5237 or is active (covered by a forward-only forwarding declaration) 5238 and will not create an empty zone in that case. 5239 </p> 5240<p> 5241 The current list of empty zones is: 5242 </p> 5243<div class="itemizedlist"><ul type="disc"> 5244<li>10.IN-ADDR.ARPA</li> 5245<li>16.172.IN-ADDR.ARPA</li> 5246<li>17.172.IN-ADDR.ARPA</li> 5247<li>18.172.IN-ADDR.ARPA</li> 5248<li>19.172.IN-ADDR.ARPA</li> 5249<li>20.172.IN-ADDR.ARPA</li> 5250<li>21.172.IN-ADDR.ARPA</li> 5251<li>22.172.IN-ADDR.ARPA</li> 5252<li>23.172.IN-ADDR.ARPA</li> 5253<li>24.172.IN-ADDR.ARPA</li> 5254<li>25.172.IN-ADDR.ARPA</li> 5255<li>26.172.IN-ADDR.ARPA</li> 5256<li>27.172.IN-ADDR.ARPA</li> 5257<li>28.172.IN-ADDR.ARPA</li> 5258<li>29.172.IN-ADDR.ARPA</li> 5259<li>30.172.IN-ADDR.ARPA</li> 5260<li>31.172.IN-ADDR.ARPA</li> 5261<li>168.192.IN-ADDR.ARPA</li> 5262<li>0.IN-ADDR.ARPA</li> 5263<li>127.IN-ADDR.ARPA</li> 5264<li>254.169.IN-ADDR.ARPA</li> 5265<li>2.0.192.IN-ADDR.ARPA</li> 5266<li>100.51.198.IN-ADDR.ARPA</li> 5267<li>113.0.203.IN-ADDR.ARPA</li> 5268<li>255.255.255.255.IN-ADDR.ARPA</li> 5269<li>0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA</li> 5270<li>1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA</li> 5271<li>8.B.D.0.1.0.0.2.IP6.ARPA</li> 5272<li>D.F.IP6.ARPA</li> 5273<li>8.E.F.IP6.ARPA</li> 5274<li>9.E.F.IP6.ARPA</li> 5275<li>A.E.F.IP6.ARPA</li> 5276<li>B.E.F.IP6.ARPA</li> 5277</ul></div> 5278<p> 5279 </p> 5280<p> 5281 Empty zones are settable at the view level and only apply to 5282 views of class IN. Disabled empty zones are only inherited 5283 from options if there are no disabled empty zones specified 5284 at the view level. To override the options list of disabled 5285 zones, you can disable the root zone at the view level, for example: 5286</p> 5287<pre class="programlisting"> 5288 disable-empty-zone "."; 5289</pre> 5290<p> 5291 </p> 5292<p> 5293 If you are using the address ranges covered here, you should 5294 already have reverse zones covering the addresses you use. 5295 In practice this appears to not be the case with many queries 5296 being made to the infrastructure servers for names in these 5297 spaces. So many in fact that sacrificial servers were needed 5298 to be deployed to channel the query load away from the 5299 infrastructure servers. 5300 </p> 5301<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 5302<h3 class="title">Note</h3> 5303 The real parent servers for these zones should disable all 5304 empty zone under the parent zone they serve. For the real 5305 root servers, this is all built-in empty zones. This will 5306 enable them to return referrals to deeper in the tree. 5307 </div> 5308<div class="variablelist"><dl> 5309<dt><span class="term"><span><strong class="command">empty-server</strong></span></span></dt> 5310<dd><p> 5311 Specify what server name will appear in the returned 5312 SOA record for empty zones. If none is specified, then 5313 the zone's name will be used. 5314 </p></dd> 5315<dt><span class="term"><span><strong class="command">empty-contact</strong></span></span></dt> 5316<dd><p> 5317 Specify what contact name will appear in the returned 5318 SOA record for empty zones. If none is specified, then 5319 "." will be used. 5320 </p></dd> 5321<dt><span class="term"><span><strong class="command">empty-zones-enable</strong></span></span></dt> 5322<dd><p> 5323 Enable or disable all empty zones. By default, they 5324 are enabled. 5325 </p></dd> 5326<dt><span class="term"><span><strong class="command">disable-empty-zone</strong></span></span></dt> 5327<dd><p> 5328 Disable individual empty zones. By default, none are 5329 disabled. This option can be specified multiple times. 5330 </p></dd> 5331</dl></div> 5332</div> 5333<div class="sect3" lang="en"> 5334<div class="titlepage"><div><div><h4 class="title"> 5335<a name="acache"></a>Additional Section Caching</h4></div></div></div> 5336<p> 5337 The additional section cache, also called <span><strong class="command">acache</strong></span>, 5338 is an internal cache to improve the response performance of BIND 9. 5339 When additional section caching is enabled, BIND 9 will 5340 cache an internal short-cut to the additional section content for 5341 each answer RR. 5342 Note that <span><strong class="command">acache</strong></span> is an internal caching 5343 mechanism of BIND 9, and is not related to the DNS caching 5344 server function. 5345 </p> 5346<p> 5347 Additional section caching does not change the 5348 response content (except the RRsets ordering of the additional 5349 section, see below), but can improve the response performance 5350 significantly. 5351 It is particularly effective when BIND 9 acts as an authoritative 5352 server for a zone that has many delegations with many glue RRs. 5353 </p> 5354<p> 5355 In order to obtain the maximum performance improvement 5356 from additional section caching, setting 5357 <span><strong class="command">additional-from-cache</strong></span> 5358 to <span><strong class="command">no</strong></span> is recommended, since the current 5359 implementation of <span><strong class="command">acache</strong></span> 5360 does not short-cut of additional section information from the 5361 DNS cache data. 5362 </p> 5363<p> 5364 One obvious disadvantage of <span><strong class="command">acache</strong></span> is 5365 that it requires much more 5366 memory for the internal cached data. 5367 Thus, if the response performance does not matter and memory 5368 consumption is much more critical, the 5369 <span><strong class="command">acache</strong></span> mechanism can be 5370 disabled by setting <span><strong class="command">acache-enable</strong></span> to 5371 <span><strong class="command">no</strong></span>. 5372 It is also possible to specify the upper limit of memory 5373 consumption 5374 for acache by using <span><strong class="command">max-acache-size</strong></span>. 5375 </p> 5376<p> 5377 Additional section caching also has a minor effect on the 5378 RRset ordering in the additional section. 5379 Without <span><strong class="command">acache</strong></span>, 5380 <span><strong class="command">cyclic</strong></span> order is effective for the additional 5381 section as well as the answer and authority sections. 5382 However, additional section caching fixes the ordering when it 5383 first caches an RRset for the additional section, and the same 5384 ordering will be kept in succeeding responses, regardless of the 5385 setting of <span><strong class="command">rrset-order</strong></span>. 5386 The effect of this should be minor, however, since an 5387 RRset in the additional section 5388 typically only contains a small number of RRs (and in many cases 5389 it only contains a single RR), in which case the 5390 ordering does not matter much. 5391 </p> 5392<p> 5393 The following is a summary of options related to 5394 <span><strong class="command">acache</strong></span>. 5395 </p> 5396<div class="variablelist"><dl> 5397<dt><span class="term"><span><strong class="command">acache-enable</strong></span></span></dt> 5398<dd><p> 5399 If <span><strong class="command">yes</strong></span>, additional section caching is 5400 enabled. The default value is <span><strong class="command">no</strong></span>. 5401 </p></dd> 5402<dt><span class="term"><span><strong class="command">acache-cleaning-interval</strong></span></span></dt> 5403<dd><p> 5404 The server will remove stale cache entries, based on an LRU 5405 based 5406 algorithm, every <span><strong class="command">acache-cleaning-interval</strong></span> minutes. 5407 The default is 60 minutes. 5408 If set to 0, no periodic cleaning will occur. 5409 </p></dd> 5410<dt><span class="term"><span><strong class="command">max-acache-size</strong></span></span></dt> 5411<dd><p> 5412 The maximum amount of memory in bytes to use for the server's acache. 5413 When the amount of data in the acache reaches this limit, 5414 the server 5415 will clean more aggressively so that the limit is not 5416 exceeded. 5417 In a server with multiple views, the limit applies 5418 separately to the 5419 acache of each view. 5420 The default is <code class="literal">16M</code>. 5421 </p></dd> 5422</dl></div> 5423</div> 5424<div class="sect3" lang="en"> 5425<div class="titlepage"><div><div><h4 class="title"> 5426<a name="id2588188"></a>Content Filtering</h4></div></div></div> 5427<p> 5428 <acronym class="acronym">BIND</acronym> 9 provides the ability to filter 5429 out DNS responses from external DNS servers containing 5430 certain types of data in the answer section. 5431 Specifically, it can reject address (A or AAAA) records if 5432 the corresponding IPv4 or IPv6 addresses match the given 5433 <code class="varname">address_match_list</code> of the 5434 <span><strong class="command">deny-answer-addresses</strong></span> option. 5435 It can also reject CNAME or DNAME records if the "alias" 5436 name (i.e., the CNAME alias or the substituted query name 5437 due to DNAME) matches the 5438 given <code class="varname">namelist</code> of the 5439 <span><strong class="command">deny-answer-aliases</strong></span> option, where 5440 "match" means the alias name is a subdomain of one of 5441 the <code class="varname">name_list</code> elements. 5442 If the optional <code class="varname">namelist</code> is specified 5443 with <span><strong class="command">except-from</strong></span>, records whose query name 5444 matches the list will be accepted regardless of the filter 5445 setting. 5446 Likewise, if the alias name is a subdomain of the 5447 corresponding zone, the <span><strong class="command">deny-answer-aliases</strong></span> 5448 filter will not apply; 5449 for example, even if "example.com" is specified for 5450 <span><strong class="command">deny-answer-aliases</strong></span>, 5451 </p> 5452<pre class="programlisting">www.example.com. CNAME xxx.example.com.</pre> 5453<p> 5454 returned by an "example.com" server will be accepted. 5455 </p> 5456<p> 5457 In the <code class="varname">address_match_list</code> of the 5458 <span><strong class="command">deny-answer-addresses</strong></span> option, only 5459 <code class="varname">ip_addr</code> 5460 and <code class="varname">ip_prefix</code> 5461 are meaningful; 5462 any <code class="varname">key_id</code> will be silently ignored. 5463 </p> 5464<p> 5465 If a response message is rejected due to the filtering, 5466 the entire message is discarded without being cached, and 5467 a SERVFAIL error will be returned to the client. 5468 </p> 5469<p> 5470 This filtering is intended to prevent "DNS rebinding attacks," in 5471 which an attacker, in response to a query for a domain name the 5472 attacker controls, returns an IP address within your own network or 5473 an alias name within your own domain. 5474 A naive web browser or script could then serve as an 5475 unintended proxy, allowing the attacker 5476 to get access to an internal node of your local network 5477 that couldn't be externally accessed otherwise. 5478 See the paper available at 5479 <a href="" target="_top"> 5480 http://portal.acm.org/citation.cfm?id=1315245.1315298 5481 </a> 5482 for more details about the attacks. 5483 </p> 5484<p> 5485 For example, if you own a domain named "example.net" and 5486 your internal network uses an IPv4 prefix 192.0.2.0/24, 5487 you might specify the following rules: 5488 </p> 5489<pre class="programlisting">deny-answer-addresses { 192.0.2.0/24; } except-from { "example.net"; }; 5490deny-answer-aliases { "example.net"; }; 5491</pre> 5492<p> 5493 If an external attacker lets a web browser in your local 5494 network look up an IPv4 address of "attacker.example.com", 5495 the attacker's DNS server would return a response like this: 5496 </p> 5497<pre class="programlisting">attacker.example.com. A 192.0.2.1</pre> 5498<p> 5499 in the answer section. 5500 Since the rdata of this record (the IPv4 address) matches 5501 the specified prefix 192.0.2.0/24, this response will be 5502 ignored. 5503 </p> 5504<p> 5505 On the other hand, if the browser looks up a legitimate 5506 internal web server "www.example.net" and the 5507 following response is returned to 5508 the <acronym class="acronym">BIND</acronym> 9 server 5509 </p> 5510<pre class="programlisting">www.example.net. A 192.0.2.2</pre> 5511<p> 5512 it will be accepted since the owner name "www.example.net" 5513 matches the <span><strong class="command">except-from</strong></span> element, 5514 "example.net". 5515 </p> 5516<p> 5517 Note that this is not really an attack on the DNS per se. 5518 In fact, there is nothing wrong for an "external" name to 5519 be mapped to your "internal" IP address or domain name 5520 from the DNS point of view. 5521 It might actually be provided for a legitimate purpose, 5522 such as for debugging. 5523 As long as the mapping is provided by the correct owner, 5524 it is not possible or does not make sense to detect 5525 whether the intent of the mapping is legitimate or not 5526 within the DNS. 5527 The "rebinding" attack must primarily be protected at the 5528 application that uses the DNS. 5529 For a large site, however, it may be difficult to protect 5530 all possible applications at once. 5531 This filtering feature is provided only to help such an 5532 operational environment; 5533 it is generally discouraged to turn it on unless you are 5534 very sure you have no other choice and the attack is a 5535 real threat for your applications. 5536 </p> 5537<p> 5538 Care should be particularly taken if you want to use this 5539 option for addresses within 127.0.0.0/8. 5540 These addresses are obviously "internal", but many 5541 applications conventionally rely on a DNS mapping from 5542 some name to such an address. 5543 Filtering out DNS records containing this address 5544 spuriously can break such applications. 5545 </p> 5546</div> 5547<div class="sect3" lang="en"> 5548<div class="titlepage"><div><div><h4 class="title"> 5549<a name="id2588379"></a>Response Policy Zone (RPZ) Rewriting</h4></div></div></div> 5550<p> 5551 <acronym class="acronym">BIND</acronym> 9 includes an intentionally limited 5552 mechanism to modify DNS responses for recursive requests 5553 somewhat similar to email anti-spam DNS blacklists. 5554 Responses can be changed to deny the existence of domains(NXDOMAIN), 5555 deny the existence of IP addresses for domains (NODATA), 5556 or contain other IP addresses or data. 5557 </p> 5558<p> 5559 The actions encoded in a response policy zone (RPZ) are applied 5560 only to queries that ask for recursion (RD=1). 5561 Response policy zones are named in the 5562 <span><strong class="command">response-policy</strong></span> option for the view or among the 5563 global options if there is no response-policy option for the view. 5564 RPZs are ordinary DNS zones containing RRsets 5565 that can be queried normally if allowed. 5566 It is usually best to restrict those queries with something like 5567 <span><strong class="command">allow-query { localhost; };</strong></span>. 5568 </p> 5569<p> 5570 There are four kinds of RPZ records, QNAME, IP, NSIP, 5571 and NSDNAME. 5572 QNAME records are applied to query names of requests and targets 5573 of CNAME records resolved to generate the response. 5574 The owner name of a QNAME RPZ record is the query name relativized 5575 to the RPZ. 5576 </p> 5577<p> 5578 The second kind of RPZ record, an IP policy record, 5579 is triggered by addresses in A and AAAA records 5580 for the ANSWER sections of responses. 5581 IP policy records have owner names that are 5582 subdomains of <strong class="userinput"><code>rpz-ip</code></strong> relativized to the 5583 RPZ origin name and encode an IP address or address block. 5584 IPv4 addresses are encoded as 5585 <strong class="userinput"><code>prefixlength.B4.B3.B2.B1.rpz-ip</code></strong>. 5586 The prefix length must be between 1 and 32. 5587 All four bytes, B4, B3, B2, and B1, must be present. 5588 B4 is the decimal value of the least significant byte of the 5589 IPv4 address as in IN-ADDR.ARPA. 5590 IPv6 addresses are encoded in a format similar to the standard 5591 IPv6 text representation, 5592 <strong class="userinput"><code>prefixlength.W8.W7.W6.W5.W4.W3.W2.W1.rpz-ip</code></strong>. 5593 Each of W8,...,W1 is a one to four digit hexadecimal number 5594 representing 16 bits of the IPv6 address as in the standard text 5595 representation of IPv6 addresses, but reversed as in IN-ADDR.ARPA. 5596 All 8 words must be present except when consecutive 5597 zero words are replaced with <strong class="userinput"><code>.zz.</code></strong> 5598 analogous to double colons (::) in standard IPv6 text encodings. 5599 The prefix length must be between 1 and 128. 5600 </p> 5601<p> 5602 NSDNAME policy records match names of authoritative servers 5603 for the query name, a parent of the query name, a CNAME, 5604 or a parent of a CNAME. 5605 They are encoded as subdomains of 5606 <strong class="userinput"><code>rpz-nsdomain</code></strong> relativized 5607 to the RPZ origin name. 5608 </p> 5609<p> 5610 NSIP policy records match IP addresses in A and AAAA RRsets 5611 for domains that can be checked against NSDNAME policy records. 5612 The are encoded like IP policies except as subdomains of 5613 <strong class="userinput"><code>rpz-nsip</code></strong>. 5614 </p> 5615<p> 5616 The query response is checked against all RPZs, so 5617 two or more policy records can apply to a single response. 5618 Because DNS responses can be rewritten according by at most a 5619 single policy record, a single policy (other than 5620 <span><strong class="command">DISABLED</strong></span> policies) must be chosen. 5621 Policies are chosen in the following order: 5622 </p> 5623<div class="itemizedlist"><ul type="disc"> 5624<li>Among applicable zones, use the RPZ that appears first 5625 in the response-policy option. 5626 </li> 5627<li>Prefer QNAME to IP to NSDNAME to NSIP policy records 5628 in a single RPZ 5629 </li> 5630<li>Among applicable NSDNAME policy records, prefer the 5631 policy record that matches the lexically smallest name 5632 </li> 5633<li>Among IP or NSIP policy records, prefer the record 5634 with the longest prefix. 5635 </li> 5636<li>Among records with the same prefex length, 5637 prefer the IP or NSIP policy record that matches 5638 the smallest IP address. 5639 </li> 5640</ul></div> 5641<p> 5642 </p> 5643<p> 5644 When the processing of a response is restarted to resolve 5645 DNAME or CNAME records and an applicable policy record set has 5646 not been found, 5647 all RPZs are again consulted for the DNAME or CNAME names 5648 and addresses. 5649 </p> 5650<p> 5651 Authority verification issues and variations in authority data 5652 can cause inconsistent results for NSIP and NSDNAME policy records. 5653 Glue NS records often differ from authoritative NS records. 5654 So they are available 5655 only when <acronym class="acronym">BIND</acronym> is built with the 5656 <strong class="userinput"><code>--enable-rpz-nsip</code></strong> or 5657 <strong class="userinput"><code>--enable-rpz-nsdname</code></strong> options 5658 on the "configure" command line. 5659 </p> 5660<p> 5661 RPZ record sets are special CNAME records or one or more 5662 of any types of DNS record except DNAME or DNSSEC. 5663 Except when a policy record is a CNAME, there can be more 5664 more than one record and more than one type 5665 in a set of policy records. 5666 Except for three kinds of CNAME records that are illegal except 5667 in policy zones, the records in a set are used in the response as if 5668 their owner name were the query name. They are copied to the 5669 response as dictated by their types. 5670 </p> 5671<div class="itemizedlist"><ul type="disc"> 5672<li>A CNAME whose target is the root domain (.) 5673 specifies the <span><strong class="command">NXDOMAIN</strong></span> policy, 5674 which generates an NXDOMAIN response. 5675 </li> 5676<li>A CNAME whose target is the wildcard top-level 5677 domain (*.) specifies the <span><strong class="command">NODATA</strong></span> policy, 5678 which rewrites the response to NODATA or ANCOUNT=1. 5679 </li> 5680<li>A CNAME whose target is a wildcard hostname such 5681 as *.example.com is used normally after the astrisk (*) 5682 has been replaced with the query name. 5683 These records are usually resolved with ordinary CNAMEs 5684 outside the policy zones. They can be useful for logging. 5685 </li> 5686<li>The <span><strong class="command">PASSTHRU</strong></span> policy is specified 5687 by a CNAME whose target is the variable part of its own 5688 owner name. It causes the response to not be rewritten 5689 and is most often used to "poke holes" in policies for 5690 CIDR blocks. 5691 </li> 5692</ul></div> 5693<p> 5694 </p> 5695<p> 5696 The policies specified in individual records 5697 in an RPZ can be overridden with a <span><strong class="command">policy</strong></span> clause 5698 in the <span><strong class="command">response-policy</strong></span> option. 5699 An organization using an RPZ provided by another organization might 5700 use this mechanism to redirect domains to its own walled garden. 5701 </p> 5702<div class="itemizedlist"><ul type="disc"> 5703<li> 5704<span><strong class="command">GIVEN</strong></span> says "do not override." 5705 </li> 5706<li> 5707<span><strong class="command">DISABLED</strong></span> causes policy records to do 5708 nothing but log what they might have done. 5709 The response to the DNS query will be written according to 5710 any matching policy records that are not disabled. 5711 Policy zones overridden with <span><strong class="command">DISABLED</strong></span> should 5712 appear first, because they will often not be logged 5713 if a higher precedence policy is found first. 5714 </li> 5715<li> 5716<span><strong class="command">PASSTHRU</strong></span> causes all policy records 5717 to act as if they were CNAME records with targets the variable 5718 part of their owner name. They protect the response from 5719 being changed. 5720 </li> 5721<li> 5722<span><strong class="command">NXDOMAIN</strong></span> causes all RPZ records 5723 to specify NXDOMAIN policies. 5724 </li> 5725<li> 5726<span><strong class="command">NODATA</strong></span> overrides with the 5727 NODATA policy 5728 </li> 5729<li> 5730<span><strong class="command">CNAME domain</strong></span> causes all RPZ 5731 policy records to act as if they were "cname domain" records. 5732 </li> 5733</ul></div> 5734<p> 5735 </p> 5736<p> 5737 For example, you might use this option statement 5738 </p> 5739<pre class="programlisting"> response-policy { zone "badlist"; };</pre> 5740<p> 5741 and this zone statement 5742 </p> 5743<pre class="programlisting"> zone "badlist" {type master; file "master/badlist"; allow-query {none;}; };</pre> 5744<p> 5745 with this zone file 5746 </p> 5747<pre class="programlisting">$TTL 1H 5748@ SOA LOCALHOST. named-mgr.example.com (1 1h 15m 30d 2h) 5749 NS LOCALHOST. 5750 5751; QNAME policy records. There are no periods (.) after the owner names. 5752nxdomain.domain.com CNAME . ; NXDOMAIN policy 5753nodata.domain.com CNAME *. ; NODATA policy 5754bad.domain.com A 10.0.0.1 ; redirect to a walled garden 5755 AAAA 2001:2::1 5756 5757; do not rewrite (PASSTHRU) OK.DOMAIN.COM 5758ok.domain.com CNAME ok.domain.com. 5759 5760bzone.domain.com CNAME garden.example.com. 5761 5762; redirect x.bzone.domain.com to x.bzone.domain.com.garden.example.com 5763*.bzone.domain.com CNAME *.garden.example.com. 5764 5765 5766; IP policy records that rewrite all answers for 127/8 except 127.0.0.1 57678.0.0.0.127.rpz-ip CNAME . 576832.1.0.0.127.rpz-ip CNAME 32.1.0.0.127. ; PASSTHRU for 127.0.0.1 5769 5770; NSDNAME and NSIP policy records 5771ns.domain.com.rpz-nsdname CNAME . 577248.zz.2.2001.rpz-nsip CNAME . 5773</pre> 5774</div> 5775</div> 5776<div class="sect2" lang="en"> 5777<div class="titlepage"><div><div><h3 class="title"> 5778<a name="server_statement_grammar"></a><span><strong class="command">server</strong></span> Statement Grammar</h3></div></div></div> 5779<pre class="programlisting"><span><strong class="command">server</strong></span> <em class="replaceable"><code>ip_addr[/prefixlen]</code></em> { 5780 [<span class="optional"> bogus <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 5781 [<span class="optional"> provide-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 5782 [<span class="optional"> request-ixfr <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 5783 [<span class="optional"> edns <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 5784 [<span class="optional"> edns-udp-size <em class="replaceable"><code>number</code></em> ; </span>] 5785 [<span class="optional"> max-udp-size <em class="replaceable"><code>number</code></em> ; </span>] 5786 [<span class="optional"> transfers <em class="replaceable"><code>number</code></em> ; </span>] 5787 [<span class="optional"> transfer-format <em class="replaceable"><code>( one-answer | many-answers )</code></em> ; ]</span>] 5788 [<span class="optional"> keys <em class="replaceable"><code>{ string ; [<span class="optional"> string ; [<span class="optional">...</span>]</span>] }</code></em> ; </span>] 5789 [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 5790 [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 5791 [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 5792 [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 5793 [<span class="optional"> query-source [<span class="optional"> address ( <em class="replaceable"><code>ip_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] 5794 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>] 5795 [<span class="optional"> query-source-v6 [<span class="optional"> address ( <em class="replaceable"><code>ip_addr</code></em> | <em class="replaceable"><code>*</code></em> ) </span>] 5796 [<span class="optional"> port ( <em class="replaceable"><code>ip_port</code></em> | <em class="replaceable"><code>*</code></em> ) </span>]; </span>] 5797 [<span class="optional"> use-queryport-pool <em class="replaceable"><code>yes_or_no</code></em>; </span>] 5798 [<span class="optional"> queryport-pool-ports <em class="replaceable"><code>number</code></em>; </span>] 5799 [<span class="optional"> queryport-pool-updateinterval <em class="replaceable"><code>number</code></em>; </span>] 5800}; 5801</pre> 5802</div> 5803<div class="sect2" lang="en"> 5804<div class="titlepage"><div><div><h3 class="title"> 5805<a name="server_statement_definition_and_usage"></a><span><strong class="command">server</strong></span> Statement Definition and 5806 Usage</h3></div></div></div> 5807<p> 5808 The <span><strong class="command">server</strong></span> statement defines 5809 characteristics 5810 to be associated with a remote name server. If a prefix length is 5811 specified, then a range of servers is covered. Only the most 5812 specific 5813 server clause applies regardless of the order in 5814 <code class="filename">named.conf</code>. 5815 </p> 5816<p> 5817 The <span><strong class="command">server</strong></span> statement can occur at 5818 the top level of the 5819 configuration file or inside a <span><strong class="command">view</strong></span> 5820 statement. 5821 If a <span><strong class="command">view</strong></span> statement contains 5822 one or more <span><strong class="command">server</strong></span> statements, only 5823 those 5824 apply to the view and any top-level ones are ignored. 5825 If a view contains no <span><strong class="command">server</strong></span> 5826 statements, 5827 any top-level <span><strong class="command">server</strong></span> statements are 5828 used as 5829 defaults. 5830 </p> 5831<p> 5832 If you discover that a remote server is giving out bad data, 5833 marking it as bogus will prevent further queries to it. The 5834 default 5835 value of <span><strong class="command">bogus</strong></span> is <span><strong class="command">no</strong></span>. 5836 </p> 5837<p> 5838 The <span><strong class="command">provide-ixfr</strong></span> clause determines 5839 whether 5840 the local server, acting as master, will respond with an 5841 incremental 5842 zone transfer when the given remote server, a slave, requests it. 5843 If set to <span><strong class="command">yes</strong></span>, incremental transfer 5844 will be provided 5845 whenever possible. If set to <span><strong class="command">no</strong></span>, 5846 all transfers 5847 to the remote server will be non-incremental. If not set, the 5848 value 5849 of the <span><strong class="command">provide-ixfr</strong></span> option in the 5850 view or 5851 global options block is used as a default. 5852 </p> 5853<p> 5854 The <span><strong class="command">request-ixfr</strong></span> clause determines 5855 whether 5856 the local server, acting as a slave, will request incremental zone 5857 transfers from the given remote server, a master. If not set, the 5858 value of the <span><strong class="command">request-ixfr</strong></span> option in 5859 the view or 5860 global options block is used as a default. 5861 </p> 5862<p> 5863 IXFR requests to servers that do not support IXFR will 5864 automatically 5865 fall back to AXFR. Therefore, there is no need to manually list 5866 which servers support IXFR and which ones do not; the global 5867 default 5868 of <span><strong class="command">yes</strong></span> should always work. 5869 The purpose of the <span><strong class="command">provide-ixfr</strong></span> and 5870 <span><strong class="command">request-ixfr</strong></span> clauses is 5871 to make it possible to disable the use of IXFR even when both 5872 master 5873 and slave claim to support it, for example if one of the servers 5874 is buggy and crashes or corrupts data when IXFR is used. 5875 </p> 5876<p> 5877 The <span><strong class="command">edns</strong></span> clause determines whether 5878 the local server will attempt to use EDNS when communicating 5879 with the remote server. The default is <span><strong class="command">yes</strong></span>. 5880 </p> 5881<p> 5882 The <span><strong class="command">edns-udp-size</strong></span> option sets the EDNS UDP size 5883 that is advertised by <span><strong class="command">named</strong></span> when querying the remote server. 5884 Valid values are 512 to 4096 bytes (values outside this range will be 5885 silently adjusted). This option is useful when you wish to 5886 advertises a different value to this server than the value you 5887 advertise globally, for example, when there is a firewall at the 5888 remote site that is blocking large replies. 5889 </p> 5890<p> 5891 The <span><strong class="command">max-udp-size</strong></span> option sets the 5892 maximum EDNS UDP message size <span><strong class="command">named</strong></span> will send. Valid 5893 values are 512 to 4096 bytes (values outside this range will 5894 be silently adjusted). This option is useful when you 5895 know that there is a firewall that is blocking large 5896 replies from <span><strong class="command">named</strong></span>. 5897 </p> 5898<p> 5899 The server supports two zone transfer methods. The first, <span><strong class="command">one-answer</strong></span>, 5900 uses one DNS message per resource record transferred. <span><strong class="command">many-answers</strong></span> packs 5901 as many resource records as possible into a message. <span><strong class="command">many-answers</strong></span> is 5902 more efficient, but is only known to be understood by <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym> 5903 8.x, and patched versions of <acronym class="acronym">BIND</acronym> 5904 4.9.5. You can specify which method 5905 to use for a server with the <span><strong class="command">transfer-format</strong></span> option. 5906 If <span><strong class="command">transfer-format</strong></span> is not 5907 specified, the <span><strong class="command">transfer-format</strong></span> 5908 specified 5909 by the <span><strong class="command">options</strong></span> statement will be 5910 used. 5911 </p> 5912<p><span><strong class="command">transfers</strong></span> 5913 is used to limit the number of concurrent inbound zone 5914 transfers from the specified server. If no 5915 <span><strong class="command">transfers</strong></span> clause is specified, the 5916 limit is set according to the 5917 <span><strong class="command">transfers-per-ns</strong></span> option. 5918 </p> 5919<p> 5920 The <span><strong class="command">keys</strong></span> clause identifies a 5921 <span><strong class="command">key_id</strong></span> defined by the <span><strong class="command">key</strong></span> statement, 5922 to be used for transaction security (TSIG, <a href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called “TSIG”</a>) 5923 when talking to the remote server. 5924 When a request is sent to the remote server, a request signature 5925 will be generated using the key specified here and appended to the 5926 message. A request originating from the remote server is not 5927 required 5928 to be signed by this key. 5929 </p> 5930<p> 5931 Although the grammar of the <span><strong class="command">keys</strong></span> 5932 clause 5933 allows for multiple keys, only a single key per server is 5934 currently 5935 supported. 5936 </p> 5937<p> 5938 The <span><strong class="command">transfer-source</strong></span> and 5939 <span><strong class="command">transfer-source-v6</strong></span> clauses specify 5940 the IPv4 and IPv6 source 5941 address to be used for zone transfer with the remote server, 5942 respectively. 5943 For an IPv4 remote server, only <span><strong class="command">transfer-source</strong></span> can 5944 be specified. 5945 Similarly, for an IPv6 remote server, only 5946 <span><strong class="command">transfer-source-v6</strong></span> can be 5947 specified. 5948 For more details, see the description of 5949 <span><strong class="command">transfer-source</strong></span> and 5950 <span><strong class="command">transfer-source-v6</strong></span> in 5951 <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 5952 </p> 5953<p> 5954 The <span><strong class="command">notify-source</strong></span> and 5955 <span><strong class="command">notify-source-v6</strong></span> clauses specify the 5956 IPv4 and IPv6 source address to be used for notify 5957 messages sent to remote servers, respectively. For an 5958 IPv4 remote server, only <span><strong class="command">notify-source</strong></span> 5959 can be specified. Similarly, for an IPv6 remote server, 5960 only <span><strong class="command">notify-source-v6</strong></span> can be specified. 5961 </p> 5962<p> 5963 The <span><strong class="command">query-source</strong></span> and 5964 <span><strong class="command">query-source-v6</strong></span> clauses specify the 5965 IPv4 and IPv6 source address to be used for queries 5966 sent to remote servers, respectively. For an IPv4 5967 remote server, only <span><strong class="command">query-source</strong></span> can 5968 be specified. Similarly, for an IPv6 remote server, 5969 only <span><strong class="command">query-source-v6</strong></span> can be specified. 5970 </p> 5971</div> 5972<div class="sect2" lang="en"> 5973<div class="titlepage"><div><div><h3 class="title"> 5974<a name="statschannels"></a><span><strong class="command">statistics-channels</strong></span> Statement Grammar</h3></div></div></div> 5975<pre class="programlisting"><span><strong class="command">statistics-channels</strong></span> { 5976 [ inet ( ip_addr | * ) [ port ip_port ] 5977 [ allow { <em class="replaceable"><code> address_match_list </code></em> } ]; ] 5978 [ inet ...; ] 5979}; 5980</pre> 5981</div> 5982<div class="sect2" lang="en"> 5983<div class="titlepage"><div><div><h3 class="title"> 5984<a name="id2589481"></a><span><strong class="command">statistics-channels</strong></span> Statement Definition and 5985 Usage</h3></div></div></div> 5986<p> 5987 The <span><strong class="command">statistics-channels</strong></span> statement 5988 declares communication channels to be used by system 5989 administrators to get access to statistics information of 5990 the name server. 5991 </p> 5992<p> 5993 This statement intends to be flexible to support multiple 5994 communication protocols in the future, but currently only 5995 HTTP access is supported. 5996 It requires that BIND 9 be compiled with libxml2; 5997 the <span><strong class="command">statistics-channels</strong></span> statement is 5998 still accepted even if it is built without the library, 5999 but any HTTP access will fail with an error. 6000 </p> 6001<p> 6002 An <span><strong class="command">inet</strong></span> control channel is a TCP socket 6003 listening at the specified <span><strong class="command">ip_port</strong></span> on the 6004 specified <span><strong class="command">ip_addr</strong></span>, which can be an IPv4 or IPv6 6005 address. An <span><strong class="command">ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is 6006 interpreted as the IPv4 wildcard address; connections will be 6007 accepted on any of the system's IPv4 addresses. 6008 To listen on the IPv6 wildcard address, 6009 use an <span><strong class="command">ip_addr</strong></span> of <code class="literal">::</code>. 6010 </p> 6011<p> 6012 If no port is specified, port 80 is used for HTTP channels. 6013 The asterisk "<code class="literal">*</code>" cannot be used for 6014 <span><strong class="command">ip_port</strong></span>. 6015 </p> 6016<p> 6017 The attempt of opening a statistics channel is 6018 restricted by the optional <span><strong class="command">allow</strong></span> clause. 6019 Connections to the statistics channel are permitted based on the 6020 <span><strong class="command">address_match_list</strong></span>. 6021 If no <span><strong class="command">allow</strong></span> clause is present, 6022 <span><strong class="command">named</strong></span> accepts connection 6023 attempts from any address; since the statistics may 6024 contain sensitive internal information, it is highly 6025 recommended to restrict the source of connection requests 6026 appropriately. 6027 </p> 6028<p> 6029 If no <span><strong class="command">statistics-channels</strong></span> statement is present, 6030 <span><strong class="command">named</strong></span> will not open any communication channels. 6031 </p> 6032</div> 6033<div class="sect2" lang="en"> 6034<div class="titlepage"><div><div><h3 class="title"> 6035<a name="trusted-keys"></a><span><strong class="command">trusted-keys</strong></span> Statement Grammar</h3></div></div></div> 6036<pre class="programlisting"><span><strong class="command">trusted-keys</strong></span> { 6037 <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; 6038 [<span class="optional"> <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; [<span class="optional">...</span>]</span>] 6039}; 6040</pre> 6041</div> 6042<div class="sect2" lang="en"> 6043<div class="titlepage"><div><div><h3 class="title"> 6044<a name="id2589689"></a><span><strong class="command">trusted-keys</strong></span> Statement Definition 6045 and Usage</h3></div></div></div> 6046<p> 6047 The <span><strong class="command">trusted-keys</strong></span> statement defines 6048 DNSSEC security roots. DNSSEC is described in <a href="Bv9ARM.ch04.html#DNSSEC" title="DNSSEC">the section called “DNSSEC”</a>. A security root is defined when the 6049 public key for a non-authoritative zone is known, but 6050 cannot be securely obtained through DNS, either because 6051 it is the DNS root zone or because its parent zone is 6052 unsigned. Once a key has been configured as a trusted 6053 key, it is treated as if it had been validated and 6054 proven secure. The resolver attempts DNSSEC validation 6055 on all DNS data in subdomains of a security root. 6056 </p> 6057<p> 6058 All keys (and corresponding zones) listed in 6059 <span><strong class="command">trusted-keys</strong></span> are deemed to exist regardless 6060 of what parent zones say. Similarly for all keys listed in 6061 <span><strong class="command">trusted-keys</strong></span> only those keys are 6062 used to validate the DNSKEY RRset. The parent's DS RRset 6063 will not be used. 6064 </p> 6065<p> 6066 The <span><strong class="command">trusted-keys</strong></span> statement can contain 6067 multiple key entries, each consisting of the key's 6068 domain name, flags, protocol, algorithm, and the Base-64 6069 representation of the key data. 6070 Spaces, tabs, newlines and carriage returns are ignored 6071 in the key data, so the configuration may be split up into 6072 multiple lines. 6073 </p> 6074<p> 6075 <span><strong class="command">trusted-keys</strong></span> may be set at the top level 6076 of <code class="filename">named.conf</code> or within a view. If it is 6077 set in both places, they are additive: keys defined at the top 6078 level are inherited by all views, but keys defined in a view 6079 are only used within that view. 6080 </p> 6081</div> 6082<div class="sect2" lang="en"> 6083<div class="titlepage"><div><div><h3 class="title"> 6084<a name="id2589736"></a><span><strong class="command">managed-keys</strong></span> Statement Grammar</h3></div></div></div> 6085<pre class="programlisting"><span><strong class="command">managed-keys</strong></span> { 6086 <em class="replaceable"><code>string</code></em> initial-key <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; 6087 [<span class="optional"> <em class="replaceable"><code>string</code></em> initial-key <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; [<span class="optional">...</span>]</span>] 6088}; 6089</pre> 6090</div> 6091<div class="sect2" lang="en"> 6092<div class="titlepage"><div><div><h3 class="title"> 6093<a name="managed-keys"></a><span><strong class="command">managed-keys</strong></span> Statement Definition 6094 and Usage</h3></div></div></div> 6095<p> 6096 The <span><strong class="command">managed-keys</strong></span> statement, like 6097 <span><strong class="command">trusted-keys</strong></span>, defines DNSSEC 6098 security roots. The difference is that 6099 <span><strong class="command">managed-keys</strong></span> can be kept up to date 6100 automatically, without intervention from the resolver 6101 operator. 6102 </p> 6103<p> 6104 Suppose, for example, that a zone's key-signing 6105 key was compromised, and the zone owner had to revoke and 6106 replace the key. A resolver which had the old key in a 6107 <span><strong class="command">trusted-keys</strong></span> statement would be 6108 unable to validate this zone any longer; it would 6109 reply with a SERVFAIL response code. This would 6110 continue until the resolver operator had updated the 6111 <span><strong class="command">trusted-keys</strong></span> statement with the new key. 6112 </p> 6113<p> 6114 If, however, the zone were listed in a 6115 <span><strong class="command">managed-keys</strong></span> statement instead, then the 6116 zone owner could add a "stand-by" key to the zone in advance. 6117 <span><strong class="command">named</strong></span> would store the stand-by key, and 6118 when the original key was revoked, <span><strong class="command">named</strong></span> 6119 would be able to transition smoothly to the new key. It would 6120 also recognize that the old key had been revoked, and cease 6121 using that key to validate answers, minimizing the damage that 6122 the compromised key could do. 6123 </p> 6124<p> 6125 A <span><strong class="command">managed-keys</strong></span> statement contains a list of 6126 the keys to be managed, along with information about how the 6127 keys are to be initialized for the first time. The only 6128 initialization method currently supported (as of 6129 <acronym class="acronym">BIND</acronym> 9.7.0) is <code class="literal">initial-key</code>. 6130 This means the <span><strong class="command">managed-keys</strong></span> statement must 6131 contain a copy of the initializing key. (Future releases may 6132 allow keys to be initialized by other methods, eliminating this 6133 requirement.) 6134 </p> 6135<p> 6136 Consequently, a <span><strong class="command">managed-keys</strong></span> statement 6137 appears similar to a <span><strong class="command">trusted-keys</strong></span>, differing 6138 in the presence of the second field, containing the keyword 6139 <code class="literal">initial-key</code>. The difference is, whereas the 6140 keys listed in a <span><strong class="command">trusted-keys</strong></span> continue to be 6141 trusted until they are removed from 6142 <code class="filename">named.conf</code>, an initializing key listed 6143 in a <span><strong class="command">managed-keys</strong></span> statement is only trusted 6144 <span class="emphasis"><em>once</em></span>: for as long as it takes to load the 6145 managed key database and start the RFC 5011 key maintenance 6146 process. 6147 </p> 6148<p> 6149 The first time <span><strong class="command">named</strong></span> runs with a managed key 6150 configured in <code class="filename">named.conf</code>, it fetches the 6151 DNSKEY RRset directly from the zone apex, and validates it 6152 using the key specified in the <span><strong class="command">managed-keys</strong></span> 6153 statement. If the DNSKEY RRset is validly signed, then it is 6154 used as the basis for a new managed keys database. 6155 </p> 6156<p> 6157 From that point on, whenever <span><strong class="command">named</strong></span> runs, it 6158 sees the <span><strong class="command">managed-keys</strong></span> statement, checks to 6159 make sure RFC 5011 key maintenance has already been initialized 6160 for the specified domain, and if so, it simply moves on. The 6161 key specified in the <span><strong class="command">managed-keys</strong></span> is not 6162 used to validate answers; it has been superseded by the key or 6163 keys stored in the managed keys database. 6164 </p> 6165<p> 6166 The next time <span><strong class="command">named</strong></span> runs after a name 6167 has been <span class="emphasis"><em>removed</em></span> from the 6168 <span><strong class="command">managed-keys</strong></span> statement, the corresponding 6169 zone will be removed from the managed keys database, 6170 and RFC 5011 key maintenance will no longer be used for that 6171 domain. 6172 </p> 6173<p> 6174 <span><strong class="command">named</strong></span> only maintains a single managed keys 6175 database; consequently, unlike <span><strong class="command">trusted-keys</strong></span>, 6176 <span><strong class="command">managed-keys</strong></span> may only be set at the top 6177 level of <code class="filename">named.conf</code>, not within a view. 6178 </p> 6179<p> 6180 In the current implementation, the managed keys database is 6181 stored as a master-format zone file called 6182 <code class="filename">managed-keys.bind</code>. When the key database 6183 is changed, the zone is updated. As with any other dynamic 6184 zone, changes will be written into a journal file, 6185 <code class="filename">managed-keys.bind.jnl</code>. They are committed 6186 to the master file as soon as possible afterward; in the case 6187 of the managed key database, this will usually occur within 30 6188 seconds. So, whenever <span><strong class="command">named</strong></span> is using 6189 automatic key maintenance, those two files can be expected to 6190 exist in the working directory. (For this reason among others, 6191 the working directory should be always be writable by 6192 <span><strong class="command">named</strong></span>.) 6193 </p> 6194<p> 6195 If the <span><strong class="command">dnssec-lookaside</strong></span> option is 6196 set to <strong class="userinput"><code>auto</code></strong>, <span><strong class="command">named</strong></span> 6197 will automatically initialize a managed key for the 6198 zone <code class="literal">dlv.isc.org</code>. The key that is 6199 used to initialize the key maintenance process is built 6200 into <span><strong class="command">named</strong></span>, and can be overridden 6201 from <span><strong class="command">bindkeys-file</strong></span>. 6202 </p> 6203</div> 6204<div class="sect2" lang="en"> 6205<div class="titlepage"><div><div><h3 class="title"> 6206<a name="view_statement_grammar"></a><span><strong class="command">view</strong></span> Statement Grammar</h3></div></div></div> 6207<pre class="programlisting"><span><strong class="command">view</strong></span> <em class="replaceable"><code>view_name</code></em> 6208 [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { 6209 match-clients { <em class="replaceable"><code>address_match_list</code></em> }; 6210 match-destinations { <em class="replaceable"><code>address_match_list</code></em> }; 6211 match-recursive-only <em class="replaceable"><code>yes_or_no</code></em> ; 6212 [<span class="optional"> <em class="replaceable"><code>view_option</code></em>; ...</span>] 6213 [<span class="optional"> <em class="replaceable"><code>zone_statement</code></em>; ...</span>] 6214}; 6215</pre> 6216</div> 6217<div class="sect2" lang="en"> 6218<div class="titlepage"><div><div><h3 class="title"> 6219<a name="id2590162"></a><span><strong class="command">view</strong></span> Statement Definition and Usage</h3></div></div></div> 6220<p> 6221 The <span><strong class="command">view</strong></span> statement is a powerful 6222 feature 6223 of <acronym class="acronym">BIND</acronym> 9 that lets a name server 6224 answer a DNS query differently 6225 depending on who is asking. It is particularly useful for 6226 implementing 6227 split DNS setups without having to run multiple servers. 6228 </p> 6229<p> 6230 Each <span><strong class="command">view</strong></span> statement defines a view 6231 of the 6232 DNS namespace that will be seen by a subset of clients. A client 6233 matches 6234 a view if its source IP address matches the 6235 <code class="varname">address_match_list</code> of the view's 6236 <span><strong class="command">match-clients</strong></span> clause and its 6237 destination IP address matches 6238 the <code class="varname">address_match_list</code> of the 6239 view's 6240 <span><strong class="command">match-destinations</strong></span> clause. If not 6241 specified, both 6242 <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span> 6243 default to matching all addresses. In addition to checking IP 6244 addresses 6245 <span><strong class="command">match-clients</strong></span> and <span><strong class="command">match-destinations</strong></span> 6246 can also take <span><strong class="command">keys</strong></span> which provide an 6247 mechanism for the 6248 client to select the view. A view can also be specified 6249 as <span><strong class="command">match-recursive-only</strong></span>, which 6250 means that only recursive 6251 requests from matching clients will match that view. 6252 The order of the <span><strong class="command">view</strong></span> statements is 6253 significant — 6254 a client request will be resolved in the context of the first 6255 <span><strong class="command">view</strong></span> that it matches. 6256 </p> 6257<p> 6258 Zones defined within a <span><strong class="command">view</strong></span> 6259 statement will 6260 only be accessible to clients that match the <span><strong class="command">view</strong></span>. 6261 By defining a zone of the same name in multiple views, different 6262 zone data can be given to different clients, for example, 6263 "internal" 6264 and "external" clients in a split DNS setup. 6265 </p> 6266<p> 6267 Many of the options given in the <span><strong class="command">options</strong></span> statement 6268 can also be used within a <span><strong class="command">view</strong></span> 6269 statement, and then 6270 apply only when resolving queries with that view. When no 6271 view-specific 6272 value is given, the value in the <span><strong class="command">options</strong></span> statement 6273 is used as a default. Also, zone options can have default values 6274 specified 6275 in the <span><strong class="command">view</strong></span> statement; these 6276 view-specific defaults 6277 take precedence over those in the <span><strong class="command">options</strong></span> statement. 6278 </p> 6279<p> 6280 Views are class specific. If no class is given, class IN 6281 is assumed. Note that all non-IN views must contain a hint zone, 6282 since only the IN class has compiled-in default hints. 6283 </p> 6284<p> 6285 If there are no <span><strong class="command">view</strong></span> statements in 6286 the config 6287 file, a default view that matches any client is automatically 6288 created 6289 in class IN. Any <span><strong class="command">zone</strong></span> statements 6290 specified on 6291 the top level of the configuration file are considered to be part 6292 of 6293 this default view, and the <span><strong class="command">options</strong></span> 6294 statement will 6295 apply to the default view. If any explicit <span><strong class="command">view</strong></span> 6296 statements are present, all <span><strong class="command">zone</strong></span> 6297 statements must 6298 occur inside <span><strong class="command">view</strong></span> statements. 6299 </p> 6300<p> 6301 Here is an example of a typical split DNS setup implemented 6302 using <span><strong class="command">view</strong></span> statements: 6303 </p> 6304<pre class="programlisting">view "internal" { 6305 // This should match our internal networks. 6306 match-clients { 10.0.0.0/8; }; 6307 6308 // Provide recursive service to internal 6309 // clients only. 6310 recursion yes; 6311 6312 // Provide a complete view of the example.com 6313 // zone including addresses of internal hosts. 6314 zone "example.com" { 6315 type master; 6316 file "example-internal.db"; 6317 }; 6318}; 6319 6320view "external" { 6321 // Match all clients not matched by the 6322 // previous view. 6323 match-clients { any; }; 6324 6325 // Refuse recursive service to external clients. 6326 recursion no; 6327 6328 // Provide a restricted view of the example.com 6329 // zone containing only publicly accessible hosts. 6330 zone "example.com" { 6331 type master; 6332 file "example-external.db"; 6333 }; 6334}; 6335</pre> 6336</div> 6337<div class="sect2" lang="en"> 6338<div class="titlepage"><div><div><h3 class="title"> 6339<a name="zone_statement_grammar"></a><span><strong class="command">zone</strong></span> 6340 Statement Grammar</h3></div></div></div> 6341<pre class="programlisting"><span><strong class="command">zone</strong></span> <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { 6342 type master; 6343 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6344 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6345 [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6346 [<span class="optional"> allow-update { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6347 [<span class="optional"> update-policy <em class="replaceable"><code>local</code></em> | { <em class="replaceable"><code>update_policy_rule</code></em> [<span class="optional">...</span>] }; </span>] 6348 [<span class="optional"> also-notify { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; 6349 [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] 6350 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] 6351 [<span class="optional"> check-mx (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] 6352 [<span class="optional"> check-wildcard <em class="replaceable"><code>yes_or_no</code></em>; </span>] 6353 [<span class="optional"> check-integrity <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6354 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>] 6355 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>] 6356 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>] 6357 [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>] 6358 [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>] 6359 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>] 6360 [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] 6361 [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>] 6362 [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>] 6363 [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>] 6364 [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6365 [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>] 6366 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>] 6367 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>] 6368 [<span class="optional"> notify <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>explicit</code></em> | <em class="replaceable"><code>master-only</code></em> ; </span>] 6369 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>] 6370 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>] 6371 [<span class="optional"> pubkey <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; </span>] 6372 [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6373 [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6374 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6375 [<span class="optional"> sig-validity-interval <em class="replaceable"><code>number</code></em> [<span class="optional"><em class="replaceable"><code>number</code></em></span>] ; </span>] 6376 [<span class="optional"> sig-signing-nodes <em class="replaceable"><code>number</code></em> ; </span>] 6377 [<span class="optional"> sig-signing-signatures <em class="replaceable"><code>number</code></em> ; </span>] 6378 [<span class="optional"> sig-signing-type <em class="replaceable"><code>number</code></em> ; </span>] 6379 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>] 6380 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] 6381 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] 6382 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>] 6383 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>] 6384 [<span class="optional"> key-directory <em class="replaceable"><code>path_name</code></em>; </span>] 6385 [<span class="optional"> auto-dnssec <code class="constant">allow</code>|<code class="constant">maintain</code>|<code class="constant">off</code>; </span>] 6386 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6387}; 6388 6389zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { 6390 type slave; 6391 [<span class="optional"> allow-notify { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6392 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6393 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6394 [<span class="optional"> allow-transfer { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6395 [<span class="optional"> allow-update-forwarding { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6396 [<span class="optional"> update-check-ksk <em class="replaceable"><code>yes_or_no</code></em>; </span>] 6397 [<span class="optional"> dnssec-update-mode ( <em class="replaceable"><code>maintain</code></em> | <em class="replaceable"><code>no-resign</code></em> ); </span>] 6398 [<span class="optional"> dnssec-dnskey-kskonly <em class="replaceable"><code>yes_or_no</code></em>; </span>] 6399 [<span class="optional"> dnssec-secure-to-insecure <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6400 [<span class="optional"> try-tcp-refresh <em class="replaceable"><code>yes_or_no</code></em>; </span>] 6401 [<span class="optional"> also-notify { <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; 6402 [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] 6403 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] 6404 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>] 6405 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>] 6406 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>] 6407 [<span class="optional"> journal <em class="replaceable"><code>string</code></em> ; </span>] 6408 [<span class="optional"> max-journal-size <em class="replaceable"><code>size_spec</code></em>; </span>] 6409 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>] 6410 [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] 6411 [<span class="optional"> ixfr-base <em class="replaceable"><code>string</code></em> ; </span>] 6412 [<span class="optional"> ixfr-from-differences <em class="replaceable"><code>yes_or_no</code></em>; </span>] 6413 [<span class="optional"> ixfr-tmp-file <em class="replaceable"><code>string</code></em> ; </span>] 6414 [<span class="optional"> maintain-ixfr-base <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6415 [<span class="optional"> masters [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>masters_list</code></em> | <em class="replaceable"><code>ip_addr</code></em> 6416 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] 6417 [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] }; </span>] 6418 [<span class="optional"> max-ixfr-log-size <em class="replaceable"><code>number</code></em> ; </span>] 6419 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>] 6420 [<span class="optional"> max-transfer-idle-out <em class="replaceable"><code>number</code></em> ; </span>] 6421 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>] 6422 [<span class="optional"> max-transfer-time-out <em class="replaceable"><code>number</code></em> ; </span>] 6423 [<span class="optional"> notify <em class="replaceable"><code>yes_or_no</code></em> | <em class="replaceable"><code>explicit</code></em> | <em class="replaceable"><code>master-only</code></em> ; </span>] 6424 [<span class="optional"> notify-delay <em class="replaceable"><code>seconds</code></em> ; </span>] 6425 [<span class="optional"> notify-to-soa <em class="replaceable"><code>yes_or_no</code></em>; </span>] 6426 [<span class="optional"> pubkey <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; </span>] 6427 [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6428 [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6429 [<span class="optional"> alt-transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6430 [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) 6431 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6432 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>] 6433 [<span class="optional"> notify-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6434 [<span class="optional"> notify-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6435 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6436 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>] 6437 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] 6438 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] 6439 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>] 6440 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>] 6441 [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6442 [<span class="optional"> zero-no-soa-ttl <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6443}; 6444 6445zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { 6446 type hint; 6447 file <em class="replaceable"><code>string</code></em> ; 6448 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6449 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] // Not Implemented. 6450}; 6451 6452zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { 6453 type stub; 6454 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6455 [<span class="optional"> allow-query-on { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6456 [<span class="optional"> check-names (<code class="constant">warn</code>|<code class="constant">fail</code>|<code class="constant">ignore</code>) ; </span>] 6457 [<span class="optional"> dialup <em class="replaceable"><code>dialup_option</code></em> ; </span>] 6458 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6459 [<span class="optional"> file <em class="replaceable"><code>string</code></em> ; </span>] 6460 [<span class="optional"> masterfile-format (<code class="constant">text</code>|<code class="constant">raw</code>) ; </span>] 6461 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>] 6462 [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] 6463 [<span class="optional"> masters [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] { ( <em class="replaceable"><code>masters_list</code></em> | <em class="replaceable"><code>ip_addr</code></em> 6464 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] 6465 [<span class="optional">key <em class="replaceable"><code>key</code></em></span>] ) ; [<span class="optional">...</span>] }; </span>] 6466 [<span class="optional"> max-transfer-idle-in <em class="replaceable"><code>number</code></em> ; </span>] 6467 [<span class="optional"> max-transfer-time-in <em class="replaceable"><code>number</code></em> ; </span>] 6468 [<span class="optional"> pubkey <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>string</code></em> ; </span>] 6469 [<span class="optional"> transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6470 [<span class="optional"> transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) 6471 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6472 [<span class="optional"> alt-transfer-source (<em class="replaceable"><code>ip4_addr</code></em> | <code class="constant">*</code>) [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6473 [<span class="optional"> alt-transfer-source-v6 (<em class="replaceable"><code>ip6_addr</code></em> | <code class="constant">*</code>) 6474 [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; </span>] 6475 [<span class="optional"> use-alt-transfer-source <em class="replaceable"><code>yes_or_no</code></em>; </span>] 6476 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6477 [<span class="optional"> database <em class="replaceable"><code>string</code></em> ; </span>] 6478 [<span class="optional"> min-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] 6479 [<span class="optional"> max-refresh-time <em class="replaceable"><code>number</code></em> ; </span>] 6480 [<span class="optional"> min-retry-time <em class="replaceable"><code>number</code></em> ; </span>] 6481 [<span class="optional"> max-retry-time <em class="replaceable"><code>number</code></em> ; </span>] 6482 [<span class="optional"> multi-master <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6483}; 6484 6485zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { 6486 type static-stub; 6487 [<span class="optional"> allow-query { <em class="replaceable"><code>address_match_list</code></em> }; </span>] 6488 [<span class="optional"> server-addresses { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> ; ... </span>] }; </span>] 6489 [<span class="optional"> server-names { [<span class="optional"> <em class="replaceable"><code>namelist</code></em> </span>] }; </span>] 6490 [<span class="optional"> zone-statistics <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6491}; 6492 6493zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { 6494 type forward; 6495 [<span class="optional"> forward (<code class="constant">only</code>|<code class="constant">first</code>) ; </span>] 6496 [<span class="optional"> forwarders { [<span class="optional"> <em class="replaceable"><code>ip_addr</code></em> [<span class="optional">port <em class="replaceable"><code>ip_port</code></em></span>] ; ... </span>] }; </span>] 6497 [<span class="optional"> delegation-only <em class="replaceable"><code>yes_or_no</code></em> ; </span>] 6498}; 6499 6500zone <em class="replaceable"><code>zone_name</code></em> [<span class="optional"><em class="replaceable"><code>class</code></em></span>] { 6501 type delegation-only; 6502}; 6503 6504</pre> 6505</div> 6506<div class="sect2" lang="en"> 6507<div class="titlepage"><div><div><h3 class="title"> 6508<a name="id2591713"></a><span><strong class="command">zone</strong></span> Statement Definition and Usage</h3></div></div></div> 6509<div class="sect3" lang="en"> 6510<div class="titlepage"><div><div><h4 class="title"> 6511<a name="id2591720"></a>Zone Types</h4></div></div></div> 6512<div class="informaltable"><table border="1"> 6513<colgroup> 6514<col> 6515<col> 6516</colgroup> 6517<tbody> 6518<tr> 6519<td> 6520 <p> 6521 <code class="varname">master</code> 6522 </p> 6523 </td> 6524<td> 6525 <p> 6526 The server has a master copy of the data 6527 for the zone and will be able to provide authoritative 6528 answers for 6529 it. 6530 </p> 6531 </td> 6532</tr> 6533<tr> 6534<td> 6535 <p> 6536 <code class="varname">slave</code> 6537 </p> 6538 </td> 6539<td> 6540 <p> 6541 A slave zone is a replica of a master 6542 zone. The <span><strong class="command">masters</strong></span> list 6543 specifies one or more IP addresses 6544 of master servers that the slave contacts to update 6545 its copy of the zone. 6546 Masters list elements can also be names of other 6547 masters lists. 6548 By default, transfers are made from port 53 on the 6549 servers; this can 6550 be changed for all servers by specifying a port number 6551 before the 6552 list of IP addresses, or on a per-server basis after 6553 the IP address. 6554 Authentication to the master can also be done with 6555 per-server TSIG keys. 6556 If a file is specified, then the 6557 replica will be written to this file whenever the zone 6558 is changed, 6559 and reloaded from this file on a server restart. Use 6560 of a file is 6561 recommended, since it often speeds server startup and 6562 eliminates 6563 a needless waste of bandwidth. Note that for large 6564 numbers (in the 6565 tens or hundreds of thousands) of zones per server, it 6566 is best to 6567 use a two-level naming scheme for zone filenames. For 6568 example, 6569 a slave server for the zone <code class="literal">example.com</code> might place 6570 the zone contents into a file called 6571 <code class="filename">ex/example.com</code> where <code class="filename">ex/</code> is 6572 just the first two letters of the zone name. (Most 6573 operating systems 6574 behave very slowly if you put 100000 files into 6575 a single directory.) 6576 </p> 6577 </td> 6578</tr> 6579<tr> 6580<td> 6581 <p> 6582 <code class="varname">stub</code> 6583 </p> 6584 </td> 6585<td> 6586 <p> 6587 A stub zone is similar to a slave zone, 6588 except that it replicates only the NS records of a 6589 master zone instead 6590 of the entire zone. Stub zones are not a standard part 6591 of the DNS; 6592 they are a feature specific to the <acronym class="acronym">BIND</acronym> implementation. 6593 </p> 6594 6595 <p> 6596 Stub zones can be used to eliminate the need for glue 6597 NS record 6598 in a parent zone at the expense of maintaining a stub 6599 zone entry and 6600 a set of name server addresses in <code class="filename">named.conf</code>. 6601 This usage is not recommended for new configurations, 6602 and BIND 9 6603 supports it only in a limited way. 6604 In <acronym class="acronym">BIND</acronym> 4/8, zone 6605 transfers of a parent zone 6606 included the NS records from stub children of that 6607 zone. This meant 6608 that, in some cases, users could get away with 6609 configuring child stubs 6610 only in the master server for the parent zone. <acronym class="acronym">BIND</acronym> 6611 9 never mixes together zone data from different zones 6612 in this 6613 way. Therefore, if a <acronym class="acronym">BIND</acronym> 9 master serving a parent 6614 zone has child stub zones configured, all the slave 6615 servers for the 6616 parent zone also need to have the same child stub 6617 zones 6618 configured. 6619 </p> 6620 6621 <p> 6622 Stub zones can also be used as a way of forcing the 6623 resolution 6624 of a given domain to use a particular set of 6625 authoritative servers. 6626 For example, the caching name servers on a private 6627 network using 6628 RFC1918 addressing may be configured with stub zones 6629 for 6630 <code class="literal">10.in-addr.arpa</code> 6631 to use a set of internal name servers as the 6632 authoritative 6633 servers for that domain. 6634 </p> 6635 </td> 6636</tr> 6637<tr> 6638<td> 6639 <p> 6640 <code class="varname">static-stub</code> 6641 </p> 6642 </td> 6643<td> 6644 <p> 6645 A static-stub zone is similar to a stub zone 6646 with the following exceptions: 6647 the zone data is statically configured, rather 6648 than transferred from a master server; 6649 when recursion is necessary for a query that 6650 matches a static-stub zone, the locally 6651 configured data (nameserver names and glue addresses) 6652 is always used even if different authoritative 6653 information is cached. 6654 </p> 6655 <p> 6656 Zone data is configured via the 6657 <span><strong class="command">server-addresses</strong></span> and 6658 <span><strong class="command">server-names</strong></span> zone options. 6659 </p> 6660 <p> 6661 The zone data is maintained in the form of NS 6662 and (if necessary) glue A or AAAA RRs 6663 internally, which can be seen by dumping zone 6664 databases by <span><strong class="command">rndc dumpdb -all</strong></span>. 6665 The configured RRs are considered local configuration 6666 parameters rather than public data. 6667 Non recursive queries (i.e., those with the RD 6668 bit off) to a static-stub zone are therefore 6669 prohibited and will be responded with REFUSED. 6670 </p> 6671 <p> 6672 Since the data is statically configured, no 6673 zone maintenance action takes place for a static-stub 6674 zone. 6675 For example, there is no periodic refresh 6676 attempt, and an incoming notify message 6677 will be rejected with an rcode of NOTAUTH. 6678 </p> 6679 <p> 6680 Each static-stub zone is configured with 6681 internally generated NS and (if necessary) 6682 glue A or AAAA RRs 6683 </p> 6684 </td> 6685</tr> 6686<tr> 6687<td> 6688 <p> 6689 <code class="varname">forward</code> 6690 </p> 6691 </td> 6692<td> 6693 <p> 6694 A "forward zone" is a way to configure 6695 forwarding on a per-domain basis. A <span><strong class="command">zone</strong></span> statement 6696 of type <span><strong class="command">forward</strong></span> can 6697 contain a <span><strong class="command">forward</strong></span> 6698 and/or <span><strong class="command">forwarders</strong></span> 6699 statement, 6700 which will apply to queries within the domain given by 6701 the zone 6702 name. If no <span><strong class="command">forwarders</strong></span> 6703 statement is present or 6704 an empty list for <span><strong class="command">forwarders</strong></span> is given, then no 6705 forwarding will be done for the domain, canceling the 6706 effects of 6707 any forwarders in the <span><strong class="command">options</strong></span> statement. Thus 6708 if you want to use this type of zone to change the 6709 behavior of the 6710 global <span><strong class="command">forward</strong></span> option 6711 (that is, "forward first" 6712 to, then "forward only", or vice versa, but want to 6713 use the same 6714 servers as set globally) you need to re-specify the 6715 global forwarders. 6716 </p> 6717 </td> 6718</tr> 6719<tr> 6720<td> 6721 <p> 6722 <code class="varname">hint</code> 6723 </p> 6724 </td> 6725<td> 6726 <p> 6727 The initial set of root name servers is 6728 specified using a "hint zone". When the server starts 6729 up, it uses 6730 the root hints to find a root name server and get the 6731 most recent 6732 list of root name servers. If no hint zone is 6733 specified for class 6734 IN, the server uses a compiled-in default set of root 6735 servers hints. 6736 Classes other than IN have no built-in defaults hints. 6737 </p> 6738 </td> 6739</tr> 6740<tr> 6741<td> 6742 <p> 6743 <code class="varname">delegation-only</code> 6744 </p> 6745 </td> 6746<td> 6747 <p> 6748 This is used to enforce the delegation-only 6749 status of infrastructure zones (e.g. COM, 6750 NET, ORG). Any answer that is received 6751 without an explicit or implicit delegation 6752 in the authority section will be treated 6753 as NXDOMAIN. This does not apply to the 6754 zone apex. This should not be applied to 6755 leaf zones. 6756 </p> 6757 <p> 6758 <code class="varname">delegation-only</code> has no 6759 effect on answers received from forwarders. 6760 </p> 6761 <p> 6762 See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>. 6763 </p> 6764 </td> 6765</tr> 6766</tbody> 6767</table></div> 6768</div> 6769<div class="sect3" lang="en"> 6770<div class="titlepage"><div><div><h4 class="title"> 6771<a name="id2592402"></a>Class</h4></div></div></div> 6772<p> 6773 The zone's name may optionally be followed by a class. If 6774 a class is not specified, class <code class="literal">IN</code> (for <code class="varname">Internet</code>), 6775 is assumed. This is correct for the vast majority of cases. 6776 </p> 6777<p> 6778 The <code class="literal">hesiod</code> class is 6779 named for an information service from MIT's Project Athena. It 6780 is 6781 used to share information about various systems databases, such 6782 as users, groups, printers and so on. The keyword 6783 <code class="literal">HS</code> is 6784 a synonym for hesiod. 6785 </p> 6786<p> 6787 Another MIT development is Chaosnet, a LAN protocol created 6788 in the mid-1970s. Zone data for it can be specified with the <code class="literal">CHAOS</code> class. 6789 </p> 6790</div> 6791<div class="sect3" lang="en"> 6792<div class="titlepage"><div><div><h4 class="title"> 6793<a name="id2592503"></a>Zone Options</h4></div></div></div> 6794<div class="variablelist"><dl> 6795<dt><span class="term"><span><strong class="command">allow-notify</strong></span></span></dt> 6796<dd><p> 6797 See the description of 6798 <span><strong class="command">allow-notify</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>. 6799 </p></dd> 6800<dt><span class="term"><span><strong class="command">allow-query</strong></span></span></dt> 6801<dd><p> 6802 See the description of 6803 <span><strong class="command">allow-query</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>. 6804 </p></dd> 6805<dt><span class="term"><span><strong class="command">allow-query-on</strong></span></span></dt> 6806<dd><p> 6807 See the description of 6808 <span><strong class="command">allow-query-on</strong></span> in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>. 6809 </p></dd> 6810<dt><span class="term"><span><strong class="command">allow-transfer</strong></span></span></dt> 6811<dd><p> 6812 See the description of <span><strong class="command">allow-transfer</strong></span> 6813 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>. 6814 </p></dd> 6815<dt><span class="term"><span><strong class="command">allow-update</strong></span></span></dt> 6816<dd><p> 6817 See the description of <span><strong class="command">allow-update</strong></span> 6818 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>. 6819 </p></dd> 6820<dt><span class="term"><span><strong class="command">update-policy</strong></span></span></dt> 6821<dd><p> 6822 Specifies a "Simple Secure Update" policy. See 6823 <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</a>. 6824 </p></dd> 6825<dt><span class="term"><span><strong class="command">allow-update-forwarding</strong></span></span></dt> 6826<dd><p> 6827 See the description of <span><strong class="command">allow-update-forwarding</strong></span> 6828 in <a href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called “Access Control”</a>. 6829 </p></dd> 6830<dt><span class="term"><span><strong class="command">also-notify</strong></span></span></dt> 6831<dd><p> 6832 Only meaningful if <span><strong class="command">notify</strong></span> 6833 is 6834 active for this zone. The set of machines that will 6835 receive a 6836 <code class="literal">DNS NOTIFY</code> message 6837 for this zone is made up of all the listed name servers 6838 (other than 6839 the primary master) for the zone plus any IP addresses 6840 specified 6841 with <span><strong class="command">also-notify</strong></span>. A port 6842 may be specified 6843 with each <span><strong class="command">also-notify</strong></span> 6844 address to send the notify 6845 messages to a port other than the default of 53. 6846 <span><strong class="command">also-notify</strong></span> is not 6847 meaningful for stub zones. 6848 The default is the empty list. 6849 </p></dd> 6850<dt><span class="term"><span><strong class="command">check-names</strong></span></span></dt> 6851<dd><p> 6852 This option is used to restrict the character set and 6853 syntax of 6854 certain domain names in master files and/or DNS responses 6855 received from the 6856 network. The default varies according to zone type. For <span><strong class="command">master</strong></span> zones the default is <span><strong class="command">fail</strong></span>. For <span><strong class="command">slave</strong></span> 6857 zones the default is <span><strong class="command">warn</strong></span>. 6858 It is not implemented for <span><strong class="command">hint</strong></span> zones. 6859 </p></dd> 6860<dt><span class="term"><span><strong class="command">check-mx</strong></span></span></dt> 6861<dd><p> 6862 See the description of 6863 <span><strong class="command">check-mx</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 6864 </p></dd> 6865<dt><span class="term"><span><strong class="command">check-wildcard</strong></span></span></dt> 6866<dd><p> 6867 See the description of 6868 <span><strong class="command">check-wildcard</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 6869 </p></dd> 6870<dt><span class="term"><span><strong class="command">check-integrity</strong></span></span></dt> 6871<dd><p> 6872 See the description of 6873 <span><strong class="command">check-integrity</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 6874 </p></dd> 6875<dt><span class="term"><span><strong class="command">check-sibling</strong></span></span></dt> 6876<dd><p> 6877 See the description of 6878 <span><strong class="command">check-sibling</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 6879 </p></dd> 6880<dt><span class="term"><span><strong class="command">zero-no-soa-ttl</strong></span></span></dt> 6881<dd><p> 6882 See the description of 6883 <span><strong class="command">zero-no-soa-ttl</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 6884 </p></dd> 6885<dt><span class="term"><span><strong class="command">update-check-ksk</strong></span></span></dt> 6886<dd><p> 6887 See the description of 6888 <span><strong class="command">update-check-ksk</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 6889 </p></dd> 6890<dt><span class="term"><span><strong class="command">dnssec-dnskey-kskonly</strong></span></span></dt> 6891<dd><p> 6892 See the description of 6893 <span><strong class="command">dnssec-dnskey-kskonly</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 6894 </p></dd> 6895<dt><span class="term"><span><strong class="command">try-tcp-refresh</strong></span></span></dt> 6896<dd><p> 6897 See the description of 6898 <span><strong class="command">try-tcp-refresh</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 6899 </p></dd> 6900<dt><span class="term"><span><strong class="command">database</strong></span></span></dt> 6901<dd> 6902<p> 6903 Specify the type of database to be used for storing the 6904 zone data. The string following the <span><strong class="command">database</strong></span> keyword 6905 is interpreted as a list of whitespace-delimited words. 6906 The first word 6907 identifies the database type, and any subsequent words are 6908 passed 6909 as arguments to the database to be interpreted in a way 6910 specific 6911 to the database type. 6912 </p> 6913<p> 6914 The default is <strong class="userinput"><code>"rbt"</code></strong>, BIND 9's 6915 native in-memory 6916 red-black-tree database. This database does not take 6917 arguments. 6918 </p> 6919<p> 6920 Other values are possible if additional database drivers 6921 have been linked into the server. Some sample drivers are 6922 included 6923 with the distribution but none are linked in by default. 6924 </p> 6925</dd> 6926<dt><span class="term"><span><strong class="command">dialup</strong></span></span></dt> 6927<dd><p> 6928 See the description of 6929 <span><strong class="command">dialup</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 6930 </p></dd> 6931<dt><span class="term"><span><strong class="command">delegation-only</strong></span></span></dt> 6932<dd> 6933<p> 6934 The flag only applies to hint and stub zones. If set 6935 to <strong class="userinput"><code>yes</code></strong>, then the zone will also be 6936 treated as if it is also a delegation-only type zone. 6937 </p> 6938<p> 6939 See caveats in <a href="Bv9ARM.ch06.html#root_delegation_only"><span><strong class="command">root-delegation-only</strong></span></a>. 6940 </p> 6941</dd> 6942<dt><span class="term"><span><strong class="command">forward</strong></span></span></dt> 6943<dd><p> 6944 Only meaningful if the zone has a forwarders 6945 list. The <span><strong class="command">only</strong></span> value causes 6946 the lookup to fail 6947 after trying the forwarders and getting no answer, while <span><strong class="command">first</strong></span> would 6948 allow a normal lookup to be tried. 6949 </p></dd> 6950<dt><span class="term"><span><strong class="command">forwarders</strong></span></span></dt> 6951<dd><p> 6952 Used to override the list of global forwarders. 6953 If it is not specified in a zone of type <span><strong class="command">forward</strong></span>, 6954 no forwarding is done for the zone and the global options are 6955 not used. 6956 </p></dd> 6957<dt><span class="term"><span><strong class="command">ixfr-base</strong></span></span></dt> 6958<dd><p> 6959 Was used in <acronym class="acronym">BIND</acronym> 8 to 6960 specify the name 6961 of the transaction log (journal) file for dynamic update 6962 and IXFR. 6963 <acronym class="acronym">BIND</acronym> 9 ignores the option 6964 and constructs the name of the journal 6965 file by appending "<code class="filename">.jnl</code>" 6966 to the name of the 6967 zone file. 6968 </p></dd> 6969<dt><span class="term"><span><strong class="command">ixfr-tmp-file</strong></span></span></dt> 6970<dd><p> 6971 Was an undocumented option in <acronym class="acronym">BIND</acronym> 8. 6972 Ignored in <acronym class="acronym">BIND</acronym> 9. 6973 </p></dd> 6974<dt><span class="term"><span><strong class="command">journal</strong></span></span></dt> 6975<dd><p> 6976 Allow the default journal's filename to be overridden. 6977 The default is the zone's filename with "<code class="filename">.jnl</code>" appended. 6978 This is applicable to <span><strong class="command">master</strong></span> and <span><strong class="command">slave</strong></span> zones. 6979 </p></dd> 6980<dt><span class="term"><span><strong class="command">max-journal-size</strong></span></span></dt> 6981<dd><p> 6982 See the description of 6983 <span><strong class="command">max-journal-size</strong></span> in <a href="Bv9ARM.ch06.html#server_resource_limits" title="Server Resource Limits">the section called “Server Resource Limits”</a>. 6984 </p></dd> 6985<dt><span class="term"><span><strong class="command">max-transfer-time-in</strong></span></span></dt> 6986<dd><p> 6987 See the description of 6988 <span><strong class="command">max-transfer-time-in</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 6989 </p></dd> 6990<dt><span class="term"><span><strong class="command">max-transfer-idle-in</strong></span></span></dt> 6991<dd><p> 6992 See the description of 6993 <span><strong class="command">max-transfer-idle-in</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 6994 </p></dd> 6995<dt><span class="term"><span><strong class="command">max-transfer-time-out</strong></span></span></dt> 6996<dd><p> 6997 See the description of 6998 <span><strong class="command">max-transfer-time-out</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 6999 </p></dd> 7000<dt><span class="term"><span><strong class="command">max-transfer-idle-out</strong></span></span></dt> 7001<dd><p> 7002 See the description of 7003 <span><strong class="command">max-transfer-idle-out</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 7004 </p></dd> 7005<dt><span class="term"><span><strong class="command">notify</strong></span></span></dt> 7006<dd><p> 7007 See the description of 7008 <span><strong class="command">notify</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 7009 </p></dd> 7010<dt><span class="term"><span><strong class="command">notify-delay</strong></span></span></dt> 7011<dd><p> 7012 See the description of 7013 <span><strong class="command">notify-delay</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>. 7014 </p></dd> 7015<dt><span class="term"><span><strong class="command">notify-to-soa</strong></span></span></dt> 7016<dd><p> 7017 See the description of 7018 <span><strong class="command">notify-to-soa</strong></span> in 7019 <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 7020 </p></dd> 7021<dt><span class="term"><span><strong class="command">pubkey</strong></span></span></dt> 7022<dd><p> 7023 In <acronym class="acronym">BIND</acronym> 8, this option was 7024 intended for specifying 7025 a public zone key for verification of signatures in DNSSEC 7026 signed 7027 zones when they are loaded from disk. <acronym class="acronym">BIND</acronym> 9 does not verify signatures 7028 on load and ignores the option. 7029 </p></dd> 7030<dt><span class="term"><span><strong class="command">zone-statistics</strong></span></span></dt> 7031<dd><p> 7032 If <strong class="userinput"><code>yes</code></strong>, the server will keep 7033 statistical 7034 information for this zone, which can be dumped to the 7035 <span><strong class="command">statistics-file</strong></span> defined in 7036 the server options. 7037 </p></dd> 7038<dt><span class="term"><span><strong class="command">server-addresses</strong></span></span></dt> 7039<dd> 7040<p> 7041 Only meaningful for static-stub zones. 7042 This is a list of IP addresses to which queries 7043 should be sent in recursive resolution for the 7044 zone. 7045 A non empty list for this option will internally 7046 configure the apex NS RR with associated glue A or 7047 AAAA RRs. 7048 </p> 7049<p> 7050 For example, if "example.com" is configured as a 7051 static-stub zone with 192.0.2.1 and 2001:db8::1234 7052 in a <span><strong class="command">server-addresses</strong></span> option, 7053 the following RRs will be internally configured. 7054 </p> 7055<pre class="programlisting">example.com. NS example.com. 7056example.com. A 192.0.2.1 7057example.com. AAAA 2001:db8::1234</pre> 7058<p> 7059 These records are internally used to resolve 7060 names under the static-stub zone. 7061 For instance, if the server receives a query for 7062 "www.example.com" with the RD bit on, the server 7063 will initiate recursive resolution and send 7064 queries to 192.0.2.1 and/or 2001:db8::1234. 7065 </p> 7066</dd> 7067<dt><span class="term"><span><strong class="command">server-names</strong></span></span></dt> 7068<dd> 7069<p> 7070 Only meaningful for static-stub zones. 7071 This is a list of domain names of nameservers that 7072 act as authoritative servers of the static-stub 7073 zone. 7074 These names will be resolved to IP addresses when 7075 <span><strong class="command">named</strong></span> needs to send queries to 7076 these servers. 7077 To make this supplemental resolution successful, 7078 these names must not be a subdomain of the origin 7079 name of static-stub zone. 7080 That is, when "example.net" is the origin of a 7081 static-stub zone, "ns.example" and 7082 "master.example.com" can be specified in the 7083 <span><strong class="command">server-names</strong></span> option, but 7084 "ns.example.net" cannot, and will be rejected by 7085 the configuration parser. 7086 </p> 7087<p> 7088 A non empty list for this option will internally 7089 configure the apex NS RR with the specified names. 7090 For example, if "example.com" is configured as a 7091 static-stub zone with "ns1.example.net" and 7092 "ns2.example.net" 7093 in a <span><strong class="command">server-names</strong></span> option, 7094 the following RRs will be internally configured. 7095 </p> 7096<pre class="programlisting">example.com. NS ns1.example.net. 7097example.com. NS ns2.example.net. 7098</pre> 7099<p> 7100 These records are internally used to resolve 7101 names under the static-stub zone. 7102 For instance, if the server receives a query for 7103 "www.example.com" with the RD bit on, the server 7104 initiate recursive resolution, 7105 resolve "ns1.example.net" and/or 7106 "ns2.example.net" to IP addresses, and then send 7107 queries to (one or more of) these addresses. 7108 </p> 7109</dd> 7110<dt><span class="term"><span><strong class="command">sig-validity-interval</strong></span></span></dt> 7111<dd><p> 7112 See the description of 7113 <span><strong class="command">sig-validity-interval</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>. 7114 </p></dd> 7115<dt><span class="term"><span><strong class="command">sig-signing-nodes</strong></span></span></dt> 7116<dd><p> 7117 See the description of 7118 <span><strong class="command">sig-signing-nodes</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>. 7119 </p></dd> 7120<dt><span class="term"><span><strong class="command">sig-signing-signatures</strong></span></span></dt> 7121<dd><p> 7122 See the description of 7123 <span><strong class="command">sig-signing-signatures</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>. 7124 </p></dd> 7125<dt><span class="term"><span><strong class="command">sig-signing-type</strong></span></span></dt> 7126<dd><p> 7127 See the description of 7128 <span><strong class="command">sig-signing-type</strong></span> in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>. 7129 </p></dd> 7130<dt><span class="term"><span><strong class="command">transfer-source</strong></span></span></dt> 7131<dd><p> 7132 See the description of 7133 <span><strong class="command">transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 7134 </p></dd> 7135<dt><span class="term"><span><strong class="command">transfer-source-v6</strong></span></span></dt> 7136<dd><p> 7137 See the description of 7138 <span><strong class="command">transfer-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 7139 </p></dd> 7140<dt><span class="term"><span><strong class="command">alt-transfer-source</strong></span></span></dt> 7141<dd><p> 7142 See the description of 7143 <span><strong class="command">alt-transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 7144 </p></dd> 7145<dt><span class="term"><span><strong class="command">alt-transfer-source-v6</strong></span></span></dt> 7146<dd><p> 7147 See the description of 7148 <span><strong class="command">alt-transfer-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 7149 </p></dd> 7150<dt><span class="term"><span><strong class="command">use-alt-transfer-source</strong></span></span></dt> 7151<dd><p> 7152 See the description of 7153 <span><strong class="command">use-alt-transfer-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 7154 </p></dd> 7155<dt><span class="term"><span><strong class="command">notify-source</strong></span></span></dt> 7156<dd><p> 7157 See the description of 7158 <span><strong class="command">notify-source</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 7159 </p></dd> 7160<dt><span class="term"><span><strong class="command">notify-source-v6</strong></span></span></dt> 7161<dd><p> 7162 See the description of 7163 <span><strong class="command">notify-source-v6</strong></span> in <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. 7164 </p></dd> 7165<dt> 7166<span class="term"><span><strong class="command">min-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">max-refresh-time</strong></span>, </span><span class="term"><span><strong class="command">min-retry-time</strong></span>, </span><span class="term"><span><strong class="command">max-retry-time</strong></span></span> 7167</dt> 7168<dd><p> 7169 See the description in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>. 7170 </p></dd> 7171<dt><span class="term"><span><strong class="command">ixfr-from-differences</strong></span></span></dt> 7172<dd><p> 7173 See the description of 7174 <span><strong class="command">ixfr-from-differences</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 7175 (Note that the <span><strong class="command">ixfr-from-differences</strong></span> 7176 <strong class="userinput"><code>master</code></strong> and 7177 <strong class="userinput"><code>slave</code></strong> choices are not 7178 available at the zone level.) 7179 </p></dd> 7180<dt><span class="term"><span><strong class="command">key-directory</strong></span></span></dt> 7181<dd><p> 7182 See the description of 7183 <span><strong class="command">key-directory</strong></span> in <a href="Bv9ARM.ch06.html#options" title="options Statement Definition and 7184 Usage">the section called “<span><strong class="command">options</strong></span> Statement Definition and 7185 Usage”</a>. 7186 </p></dd> 7187<dt><span class="term"><span><strong class="command">auto-dnssec</strong></span></span></dt> 7188<dd> 7189<p> 7190 Zones configured for dynamic DNS may also use this 7191 option to allow varying levels of automatic DNSSEC key 7192 management. There are three possible settings: 7193 </p> 7194<p> 7195 <span><strong class="command">auto-dnssec allow;</strong></span> permits 7196 keys to be updated and the zone fully re-signed 7197 whenever the user issues the command <span><strong class="command">rndc sign 7198 <em class="replaceable"><code>zonename</code></em></strong></span>. 7199 </p> 7200<p> 7201 <span><strong class="command">auto-dnssec maintain;</strong></span> includes the 7202 above, but also automatically adjusts the zone's DNSSEC 7203 keys on schedule, according to the keys' timing metadata 7204 (see <a href="man.dnssec-keygen.html" title="dnssec-keygen"><span class="refentrytitle"><span class="application">dnssec-keygen</span></span>(8)</a> and 7205 <a href="man.dnssec-settime.html" title="dnssec-settime"><span class="refentrytitle"><span class="application">dnssec-settime</span></span>(8)</a>). The command 7206 <span><strong class="command">rndc sign 7207 <em class="replaceable"><code>zonename</code></em></strong></span> causes 7208 <span><strong class="command">named</strong></span> to load keys from the key 7209 repository and sign the zone with all keys that are 7210 active. 7211 <span><strong class="command">rndc loadkeys 7212 <em class="replaceable"><code>zonename</code></em></strong></span> causes 7213 <span><strong class="command">named</strong></span> to load keys from the key 7214 repository and schedule key maintenance events to occur 7215 in the future, but it does not sign the full zone 7216 immediately. Note: once keys have been loaded for a 7217 zone the first time, the repository will be searched 7218 for changes periodically, regardless of whether 7219 <span><strong class="command">rndc loadkeys</strong></span> is used. The recheck 7220 interval is hard-coded to 7221 one hour. 7222 </p> 7223<p> 7224 <span><strong class="command">auto-dnssec create;</strong></span> includes the 7225 above, but also allows <span><strong class="command">named</strong></span> 7226 to create new keys in the key repository when needed. 7227 (NOTE: This option is not yet implemented; the syntax is 7228 being reserved for future use.) 7229 </p> 7230<p> 7231 The default setting is <span><strong class="command">auto-dnssec off</strong></span>. 7232 </p> 7233</dd> 7234<dt><span class="term"><span><strong class="command">multi-master</strong></span></span></dt> 7235<dd><p> 7236 See the description of <span><strong class="command">multi-master</strong></span> in 7237 <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 7238 </p></dd> 7239<dt><span class="term"><span><strong class="command">masterfile-format</strong></span></span></dt> 7240<dd><p> 7241 See the description of <span><strong class="command">masterfile-format</strong></span> 7242 in <a href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called “Tuning”</a>. 7243 </p></dd> 7244<dt><span class="term"><span><strong class="command">dnssec-secure-to-insecure</strong></span></span></dt> 7245<dd><p> 7246 See the description of 7247 <span><strong class="command">dnssec-secure-to-insecure</strong></span> in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a>. 7248 </p></dd> 7249</dl></div> 7250</div> 7251<div class="sect3" lang="en"> 7252<div class="titlepage"><div><div><h4 class="title"> 7253<a name="dynamic_update_policies"></a>Dynamic Update Policies</h4></div></div></div> 7254<p><acronym class="acronym">BIND</acronym> 9 supports two alternative 7255 methods of granting clients the right to perform 7256 dynamic updates to a zone, configured by the 7257 <span><strong class="command">allow-update</strong></span> and 7258 <span><strong class="command">update-policy</strong></span> option, respectively. 7259 </p> 7260<p> 7261 The <span><strong class="command">allow-update</strong></span> clause works the 7262 same way as in previous versions of <acronym class="acronym">BIND</acronym>. 7263 It grants given clients the permission to update any 7264 record of any name in the zone. 7265 </p> 7266<p> 7267 The <span><strong class="command">update-policy</strong></span> clause 7268 allows more fine-grained control over what updates are 7269 allowed. A set of rules is specified, where each rule 7270 either grants or denies permissions for one or more 7271 names to be updated by one or more identities. If 7272 the dynamic update request message is signed (that is, 7273 it includes either a TSIG or SIG(0) record), the 7274 identity of the signer can be determined. 7275 </p> 7276<p> 7277 Rules are specified in the <span><strong class="command">update-policy</strong></span> 7278 zone option, and are only meaningful for master zones. 7279 When the <span><strong class="command">update-policy</strong></span> statement 7280 is present, it is a configuration error for the 7281 <span><strong class="command">allow-update</strong></span> statement to be 7282 present. The <span><strong class="command">update-policy</strong></span> statement 7283 only examines the signer of a message; the source 7284 address is not relevant. 7285 </p> 7286<p> 7287 There is a pre-defined <span><strong class="command">update-policy</strong></span> 7288 rule which can be switched on with the command 7289 <span><strong class="command">update-policy local;</strong></span>. 7290 Switching on this rule in a zone causes 7291 <span><strong class="command">named</strong></span> to generate a TSIG session 7292 key and place it in a file, and to allow that key 7293 to update the zone. (By default, the file is 7294 <code class="filename">/var/run/named/session.key</code>, the key 7295 name is "local-ddns" and the key algorithm is HMAC-SHA256, 7296 but these values are configurable with the 7297 <span><strong class="command">session-keyfile</strong></span>, 7298 <span><strong class="command">session-keyname</strong></span> and 7299 <span><strong class="command">session-keyalg</strong></span> options, respectively). 7300 </p> 7301<p> 7302 A client running on the local system, and with appropriate 7303 permissions, may read that file and use the key to sign update 7304 requests. The zone's update policy will be set to allow that 7305 key to change any record within the zone. Assuming the 7306 key name is "local-ddns", this policy is equivalent to: 7307 </p> 7308<pre class="programlisting">update-policy { grant local-ddns zonesub any; }; 7309 </pre> 7310<p> 7311 The command <span><strong class="command">nsupdate -l</strong></span> sends update 7312 requests to localhost, and signs them using the session key. 7313 </p> 7314<p> 7315 Other rule definitions look like this: 7316 </p> 7317<pre class="programlisting"> 7318( <span><strong class="command">grant</strong></span> | <span><strong class="command">deny</strong></span> ) <em class="replaceable"><code>identity</code></em> <em class="replaceable"><code>nametype</code></em> [<span class="optional"> <em class="replaceable"><code>name</code></em> </span>] [<span class="optional"> <em class="replaceable"><code>types</code></em> </span>] 7319</pre> 7320<p> 7321 Each rule grants or denies privileges. Once a message has 7322 successfully matched a rule, the operation is immediately 7323 granted or denied and no further rules are examined. A rule 7324 is matched when the signer matches the identity field, the 7325 name matches the name field in accordance with the nametype 7326 field, and the type matches the types specified in the type 7327 field. 7328 </p> 7329<p> 7330 No signer is required for <em class="replaceable"><code>tcp-self</code></em> 7331 or <em class="replaceable"><code>6to4-self</code></em> however the standard 7332 reverse mapping / prefix conversion must match the identity 7333 field. 7334 </p> 7335<p> 7336 The identity field specifies a name or a wildcard 7337 name. Normally, this is the name of the TSIG or 7338 SIG(0) key used to sign the update request. When a 7339 TKEY exchange has been used to create a shared secret, 7340 the identity of the shared secret is the same as the 7341 identity of the key used to authenticate the TKEY 7342 exchange. TKEY is also the negotiation method used 7343 by GSS-TSIG, which establishes an identity that is 7344 the Kerberos principal of the client, such as 7345 <strong class="userinput"><code>"user@host.domain"</code></strong>. When the 7346 <em class="replaceable"><code>identity</code></em> field specifies 7347 a wildcard name, it is subject to DNS wildcard 7348 expansion, so the rule will apply to multiple identities. 7349 The <em class="replaceable"><code>identity</code></em> field must 7350 contain a fully-qualified domain name. 7351 </p> 7352<p> 7353 For nametypes <code class="varname">krb5-self</code>, 7354 <code class="varname">ms-self</code>, <code class="varname">krb5-subdomain</code>, 7355 and <code class="varname">ms-subdomain</code> the 7356 <em class="replaceable"><code>identity</code></em> field specifies 7357 the Windows or Kerberos realm of the machine belongs to. 7358 </p> 7359<p> 7360 The <em class="replaceable"><code>nametype</code></em> field has 13 7361 values: 7362 <code class="varname">name</code>, <code class="varname">subdomain</code>, 7363 <code class="varname">wildcard</code>, <code class="varname">self</code>, 7364 <code class="varname">selfsub</code>, <code class="varname">selfwild</code>, 7365 <code class="varname">krb5-self</code>, <code class="varname">ms-self</code>, 7366 <code class="varname">krb5-subdomain</code>, 7367 <code class="varname">ms-subdomain</code>, 7368 <code class="varname">tcp-self</code>, <code class="varname">6to4-self</code>, 7369 <code class="varname">zonesub</code>, and <code class="varname">external</code>. 7370 </p> 7371<div class="informaltable"><table border="1"> 7372<colgroup> 7373<col> 7374<col> 7375</colgroup> 7376<tbody> 7377<tr> 7378<td> 7379 <p> 7380 <code class="varname">name</code> 7381 </p> 7382 </td> 7383<td> 7384 <p> 7385 Exact-match semantics. This rule matches 7386 when the name being updated is identical 7387 to the contents of the 7388 <em class="replaceable"><code>name</code></em> field. 7389 </p> 7390 </td> 7391</tr> 7392<tr> 7393<td> 7394 <p> 7395 <code class="varname">subdomain</code> 7396 </p> 7397 </td> 7398<td> 7399 <p> 7400 This rule matches when the name being updated 7401 is a subdomain of, or identical to, the 7402 contents of the <em class="replaceable"><code>name</code></em> 7403 field. 7404 </p> 7405 </td> 7406</tr> 7407<tr> 7408<td> 7409 <p> 7410 <code class="varname">zonesub</code> 7411 </p> 7412 </td> 7413<td> 7414 <p> 7415 This rule is similar to subdomain, except that 7416 it matches when the name being updated is a 7417 subdomain of the zone in which the 7418 <span><strong class="command">update-policy</strong></span> statement 7419 appears. This obviates the need to type the zone 7420 name twice, and enables the use of a standard 7421 <span><strong class="command">update-policy</strong></span> statement in 7422 multiple zones without modification. 7423 </p> 7424 <p> 7425 When this rule is used, the 7426 <em class="replaceable"><code>name</code></em> field is omitted. 7427 </p> 7428 </td> 7429</tr> 7430<tr> 7431<td> 7432 <p> 7433 <code class="varname">wildcard</code> 7434 </p> 7435 </td> 7436<td> 7437 <p> 7438 The <em class="replaceable"><code>name</code></em> field 7439 is subject to DNS wildcard expansion, and 7440 this rule matches when the name being updated 7441 name is a valid expansion of the wildcard. 7442 </p> 7443 </td> 7444</tr> 7445<tr> 7446<td> 7447 <p> 7448 <code class="varname">self</code> 7449 </p> 7450 </td> 7451<td> 7452 <p> 7453 This rule matches when the name being updated 7454 matches the contents of the 7455 <em class="replaceable"><code>identity</code></em> field. 7456 The <em class="replaceable"><code>name</code></em> field 7457 is ignored, but should be the same as the 7458 <em class="replaceable"><code>identity</code></em> field. 7459 The <code class="varname">self</code> nametype is 7460 most useful when allowing using one key per 7461 name to update, where the key has the same 7462 name as the name to be updated. The 7463 <em class="replaceable"><code>identity</code></em> would 7464 be specified as <code class="constant">*</code> (an asterisk) in 7465 this case. 7466 </p> 7467 </td> 7468</tr> 7469<tr> 7470<td> 7471 <p> 7472 <code class="varname">selfsub</code> 7473 </p> 7474 </td> 7475<td> 7476 <p> 7477 This rule is similar to <code class="varname">self</code> 7478 except that subdomains of <code class="varname">self</code> 7479 can also be updated. 7480 </p> 7481 </td> 7482</tr> 7483<tr> 7484<td> 7485 <p> 7486 <code class="varname">selfwild</code> 7487 </p> 7488 </td> 7489<td> 7490 <p> 7491 This rule is similar to <code class="varname">self</code> 7492 except that only subdomains of 7493 <code class="varname">self</code> can be updated. 7494 </p> 7495 </td> 7496</tr> 7497<tr> 7498<td> 7499 <p> 7500 <code class="varname">ms-self</code> 7501 </p> 7502 </td> 7503<td> 7504 <p> 7505 This rule takes a Windows machine principal 7506 (machine$@REALM) for machine in REALM and 7507 and converts it machine.realm allowing the machine 7508 to update machine.realm. The REALM to be matched 7509 is specified in the <font color="red"><replacable>identity</replacable></font> 7510 field. 7511 </p> 7512 </td> 7513</tr> 7514<tr> 7515<td> 7516 <p> 7517 <code class="varname">ms-subdomain</code> 7518 </p> 7519 </td> 7520<td> 7521 <p> 7522 This rule takes a Windows machine principal 7523 (machine$@REALM) for machine in REALM and 7524 converts it to machine.realm allowing the machine 7525 to update subdomains of machine.realm. The REALM 7526 to be matched is specified in the 7527 <font color="red"><replacable>identity</replacable></font> field. 7528 </p> 7529 </td> 7530</tr> 7531<tr> 7532<td> 7533 <p> 7534 <code class="varname">krb5-self</code> 7535 </p> 7536 </td> 7537<td> 7538 <p> 7539 This rule takes a Kerberos machine principal 7540 (host/machine@REALM) for machine in REALM and 7541 and converts it machine.realm allowing the machine 7542 to update machine.realm. The REALM to be matched 7543 is specified in the <font color="red"><replacable>identity</replacable></font> 7544 field. 7545 </p> 7546 </td> 7547</tr> 7548<tr> 7549<td> 7550 <p> 7551 <code class="varname">krb5-subdomain</code> 7552 </p> 7553 </td> 7554<td> 7555 <p> 7556 This rule takes a Kerberos machine principal 7557 (host/machine@REALM) for machine in REALM and 7558 converts it to machine.realm allowing the machine 7559 to update subdomains of machine.realm. The REALM 7560 to be matched is specified in the 7561 <font color="red"><replacable>identity</replacable></font> field. 7562 </p> 7563 </td> 7564</tr> 7565<tr> 7566<td> 7567 <p> 7568 <code class="varname">tcp-self</code> 7569 </p> 7570 </td> 7571<td> 7572 <p> 7573 Allow updates that have been sent via TCP and 7574 for which the standard mapping from the initiating 7575 IP address into the IN-ADDR.ARPA and IP6.ARPA 7576 namespaces match the name to be updated. 7577 </p> 7578 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 7579<h3 class="title">Note</h3> 7580 It is theoretically possible to spoof these TCP 7581 sessions. 7582 </div> 7583 </td> 7584</tr> 7585<tr> 7586<td> 7587 <p> 7588 <code class="varname">6to4-self</code> 7589 </p> 7590 </td> 7591<td> 7592 <p> 7593 Allow the 6to4 prefix to be update by any TCP 7594 connection from the 6to4 network or from the 7595 corresponding IPv4 address. This is intended 7596 to allow NS or DNAME RRsets to be added to the 7597 reverse tree. 7598 </p> 7599 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 7600<h3 class="title">Note</h3> 7601 It is theoretically possible to spoof these TCP 7602 sessions. 7603 </div> 7604 </td> 7605</tr> 7606<tr> 7607<td> 7608 <p> 7609 <code class="varname">external</code> 7610 </p> 7611 </td> 7612<td> 7613 <p> 7614 This rule allows <span><strong class="command">named</strong></span> 7615 to defer the decision of whether to allow a 7616 given update to an external daemon. 7617 </p> 7618 <p> 7619 The method of communicating with the daemon is 7620 specified in the <em class="replaceable"><code>identity</code></em> 7621 field, the format of which is 7622 "<code class="constant">local:</code><em class="replaceable"><code>path</code></em>", 7623 where <em class="replaceable"><code>path</code></em> is the location 7624 of a UNIX-domain socket. (Currently, "local" is the 7625 only supported mechanism.) 7626 </p> 7627 <p> 7628 Requests to the external daemon are sent over the 7629 UNIX-domain socket as datagrams with the following 7630 format: 7631 </p> 7632 <pre class="programlisting"> 7633 Protocol version number (4 bytes, network byte order, currently 1) 7634 Request length (4 bytes, network byte order) 7635 Signer (null-terminated string) 7636 Name (null-terminated string) 7637 TCP source address (null-terminated string) 7638 Rdata type (null-terminated string) 7639 Key (null-terminated string) 7640 TKEY token length (4 bytes, network byte order) 7641 TKEY token (remainder of packet)</pre> 7642 <p> 7643 The daemon replies with a four-byte value in 7644 network byte order, containing either 0 or 1; 0 7645 indicates that the specified update is not 7646 permitted, and 1 indicates that it is. 7647 </p> 7648 </td> 7649</tr> 7650</tbody> 7651</table></div> 7652<p> 7653 In all cases, the <em class="replaceable"><code>name</code></em> 7654 field must specify a fully-qualified domain name. 7655 </p> 7656<p> 7657 If no types are explicitly specified, this rule matches 7658 all types except RRSIG, NS, SOA, NSEC and NSEC3. Types 7659 may be specified by name, including "ANY" (ANY matches 7660 all types except NSEC and NSEC3, which can never be 7661 updated). Note that when an attempt is made to delete 7662 all records associated with a name, the rules are 7663 checked for each existing record type. 7664 </p> 7665</div> 7666</div> 7667</div> 7668<div class="sect1" lang="en"> 7669<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 7670<a name="id2595116"></a>Zone File</h2></div></div></div> 7671<div class="sect2" lang="en"> 7672<div class="titlepage"><div><div><h3 class="title"> 7673<a name="types_of_resource_records_and_when_to_use_them"></a>Types of Resource Records and When to Use Them</h3></div></div></div> 7674<p> 7675 This section, largely borrowed from RFC 1034, describes the 7676 concept of a Resource Record (RR) and explains when each is used. 7677 Since the publication of RFC 1034, several new RRs have been 7678 identified 7679 and implemented in the DNS. These are also included. 7680 </p> 7681<div class="sect3" lang="en"> 7682<div class="titlepage"><div><div><h4 class="title"> 7683<a name="id2595134"></a>Resource Records</h4></div></div></div> 7684<p> 7685 A domain name identifies a node. Each node has a set of 7686 resource information, which may be empty. The set of resource 7687 information associated with a particular name is composed of 7688 separate RRs. The order of RRs in a set is not significant and 7689 need not be preserved by name servers, resolvers, or other 7690 parts of the DNS. However, sorting of multiple RRs is 7691 permitted for optimization purposes, for example, to specify 7692 that a particular nearby server be tried first. See <a href="Bv9ARM.ch06.html#the_sortlist_statement" title="The sortlist Statement">the section called “The <span><strong class="command">sortlist</strong></span> Statement”</a> and <a href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called “RRset Ordering”</a>. 7693 </p> 7694<p> 7695 The components of a Resource Record are: 7696 </p> 7697<div class="informaltable"><table border="1"> 7698<colgroup> 7699<col> 7700<col> 7701</colgroup> 7702<tbody> 7703<tr> 7704<td> 7705 <p> 7706 owner name 7707 </p> 7708 </td> 7709<td> 7710 <p> 7711 The domain name where the RR is found. 7712 </p> 7713 </td> 7714</tr> 7715<tr> 7716<td> 7717 <p> 7718 type 7719 </p> 7720 </td> 7721<td> 7722 <p> 7723 An encoded 16-bit value that specifies 7724 the type of the resource record. 7725 </p> 7726 </td> 7727</tr> 7728<tr> 7729<td> 7730 <p> 7731 TTL 7732 </p> 7733 </td> 7734<td> 7735 <p> 7736 The time-to-live of the RR. This field 7737 is a 32-bit integer in units of seconds, and is 7738 primarily used by 7739 resolvers when they cache RRs. The TTL describes how 7740 long a RR can 7741 be cached before it should be discarded. 7742 </p> 7743 </td> 7744</tr> 7745<tr> 7746<td> 7747 <p> 7748 class 7749 </p> 7750 </td> 7751<td> 7752 <p> 7753 An encoded 16-bit value that identifies 7754 a protocol family or instance of a protocol. 7755 </p> 7756 </td> 7757</tr> 7758<tr> 7759<td> 7760 <p> 7761 RDATA 7762 </p> 7763 </td> 7764<td> 7765 <p> 7766 The resource data. The format of the 7767 data is type (and sometimes class) specific. 7768 </p> 7769 </td> 7770</tr> 7771</tbody> 7772</table></div> 7773<p> 7774 The following are <span class="emphasis"><em>types</em></span> of valid RRs: 7775 </p> 7776<div class="informaltable"><table border="1"> 7777<colgroup> 7778<col> 7779<col> 7780</colgroup> 7781<tbody> 7782<tr> 7783<td> 7784 <p> 7785 A 7786 </p> 7787 </td> 7788<td> 7789 <p> 7790 A host address. In the IN class, this is a 7791 32-bit IP address. Described in RFC 1035. 7792 </p> 7793 </td> 7794</tr> 7795<tr> 7796<td> 7797 <p> 7798 AAAA 7799 </p> 7800 </td> 7801<td> 7802 <p> 7803 IPv6 address. Described in RFC 1886. 7804 </p> 7805 </td> 7806</tr> 7807<tr> 7808<td> 7809 <p> 7810 A6 7811 </p> 7812 </td> 7813<td> 7814 <p> 7815 IPv6 address. This can be a partial 7816 address (a suffix) and an indirection to the name 7817 where the rest of the 7818 address (the prefix) can be found. Experimental. 7819 Described in RFC 2874. 7820 </p> 7821 </td> 7822</tr> 7823<tr> 7824<td> 7825 <p> 7826 AFSDB 7827 </p> 7828 </td> 7829<td> 7830 <p> 7831 Location of AFS database servers. 7832 Experimental. Described in RFC 1183. 7833 </p> 7834 </td> 7835</tr> 7836<tr> 7837<td> 7838 <p> 7839 APL 7840 </p> 7841 </td> 7842<td> 7843 <p> 7844 Address prefix list. Experimental. 7845 Described in RFC 3123. 7846 </p> 7847 </td> 7848</tr> 7849<tr> 7850<td> 7851 <p> 7852 CERT 7853 </p> 7854 </td> 7855<td> 7856 <p> 7857 Holds a digital certificate. 7858 Described in RFC 2538. 7859 </p> 7860 </td> 7861</tr> 7862<tr> 7863<td> 7864 <p> 7865 CNAME 7866 </p> 7867 </td> 7868<td> 7869 <p> 7870 Identifies the canonical name of an alias. 7871 Described in RFC 1035. 7872 </p> 7873 </td> 7874</tr> 7875<tr> 7876<td> 7877 <p> 7878 DHCID 7879 </p> 7880 </td> 7881<td> 7882 <p> 7883 Is used for identifying which DHCP client is 7884 associated with this name. Described in RFC 4701. 7885 </p> 7886 </td> 7887</tr> 7888<tr> 7889<td> 7890 <p> 7891 DNAME 7892 </p> 7893 </td> 7894<td> 7895 <p> 7896 Replaces the domain name specified with 7897 another name to be looked up, effectively aliasing an 7898 entire 7899 subtree of the domain name space rather than a single 7900 record 7901 as in the case of the CNAME RR. 7902 Described in RFC 2672. 7903 </p> 7904 </td> 7905</tr> 7906<tr> 7907<td> 7908 <p> 7909 DNSKEY 7910 </p> 7911 </td> 7912<td> 7913 <p> 7914 Stores a public key associated with a signed 7915 DNS zone. Described in RFC 4034. 7916 </p> 7917 </td> 7918</tr> 7919<tr> 7920<td> 7921 <p> 7922 DS 7923 </p> 7924 </td> 7925<td> 7926 <p> 7927 Stores the hash of a public key associated with a 7928 signed DNS zone. Described in RFC 4034. 7929 </p> 7930 </td> 7931</tr> 7932<tr> 7933<td> 7934 <p> 7935 GPOS 7936 </p> 7937 </td> 7938<td> 7939 <p> 7940 Specifies the global position. Superseded by LOC. 7941 </p> 7942 </td> 7943</tr> 7944<tr> 7945<td> 7946 <p> 7947 HINFO 7948 </p> 7949 </td> 7950<td> 7951 <p> 7952 Identifies the CPU and OS used by a host. 7953 Described in RFC 1035. 7954 </p> 7955 </td> 7956</tr> 7957<tr> 7958<td> 7959 <p> 7960 IPSECKEY 7961 </p> 7962 </td> 7963<td> 7964 <p> 7965 Provides a method for storing IPsec keying material in 7966 DNS. Described in RFC 4025. 7967 </p> 7968 </td> 7969</tr> 7970<tr> 7971<td> 7972 <p> 7973 ISDN 7974 </p> 7975 </td> 7976<td> 7977 <p> 7978 Representation of ISDN addresses. 7979 Experimental. Described in RFC 1183. 7980 </p> 7981 </td> 7982</tr> 7983<tr> 7984<td> 7985 <p> 7986 KEY 7987 </p> 7988 </td> 7989<td> 7990 <p> 7991 Stores a public key associated with a 7992 DNS name. Used in original DNSSEC; replaced 7993 by DNSKEY in DNSSECbis, but still used with 7994 SIG(0). Described in RFCs 2535 and 2931. 7995 </p> 7996 </td> 7997</tr> 7998<tr> 7999<td> 8000 <p> 8001 KX 8002 </p> 8003 </td> 8004<td> 8005 <p> 8006 Identifies a key exchanger for this 8007 DNS name. Described in RFC 2230. 8008 </p> 8009 </td> 8010</tr> 8011<tr> 8012<td> 8013 <p> 8014 LOC 8015 </p> 8016 </td> 8017<td> 8018 <p> 8019 For storing GPS info. Described in RFC 1876. 8020 Experimental. 8021 </p> 8022 </td> 8023</tr> 8024<tr> 8025<td> 8026 <p> 8027 MX 8028 </p> 8029 </td> 8030<td> 8031 <p> 8032 Identifies a mail exchange for the domain with 8033 a 16-bit preference value (lower is better) 8034 followed by the host name of the mail exchange. 8035 Described in RFC 974, RFC 1035. 8036 </p> 8037 </td> 8038</tr> 8039<tr> 8040<td> 8041 <p> 8042 NAPTR 8043 </p> 8044 </td> 8045<td> 8046 <p> 8047 Name authority pointer. Described in RFC 2915. 8048 </p> 8049 </td> 8050</tr> 8051<tr> 8052<td> 8053 <p> 8054 NSAP 8055 </p> 8056 </td> 8057<td> 8058 <p> 8059 A network service access point. 8060 Described in RFC 1706. 8061 </p> 8062 </td> 8063</tr> 8064<tr> 8065<td> 8066 <p> 8067 NS 8068 </p> 8069 </td> 8070<td> 8071 <p> 8072 The authoritative name server for the 8073 domain. Described in RFC 1035. 8074 </p> 8075 </td> 8076</tr> 8077<tr> 8078<td> 8079 <p> 8080 NSEC 8081 </p> 8082 </td> 8083<td> 8084 <p> 8085 Used in DNSSECbis to securely indicate that 8086 RRs with an owner name in a certain name interval do 8087 not exist in 8088 a zone and indicate what RR types are present for an 8089 existing name. 8090 Described in RFC 4034. 8091 </p> 8092 </td> 8093</tr> 8094<tr> 8095<td> 8096 <p> 8097 NSEC3 8098 </p> 8099 </td> 8100<td> 8101 <p> 8102 Used in DNSSECbis to securely indicate that 8103 RRs with an owner name in a certain name 8104 interval do not exist in a zone and indicate 8105 what RR types are present for an existing 8106 name. NSEC3 differs from NSEC in that it 8107 prevents zone enumeration but is more 8108 computationally expensive on both the server 8109 and the client than NSEC. Described in RFC 8110 5155. 8111 </p> 8112 </td> 8113</tr> 8114<tr> 8115<td> 8116 <p> 8117 NSEC3PARAM 8118 </p> 8119 </td> 8120<td> 8121 <p> 8122 Used in DNSSECbis to tell the authoritative 8123 server which NSEC3 chains are available to use. 8124 Described in RFC 5155. 8125 </p> 8126 </td> 8127</tr> 8128<tr> 8129<td> 8130 <p> 8131 NXT 8132 </p> 8133 </td> 8134<td> 8135 <p> 8136 Used in DNSSEC to securely indicate that 8137 RRs with an owner name in a certain name interval do 8138 not exist in 8139 a zone and indicate what RR types are present for an 8140 existing name. 8141 Used in original DNSSEC; replaced by NSEC in 8142 DNSSECbis. 8143 Described in RFC 2535. 8144 </p> 8145 </td> 8146</tr> 8147<tr> 8148<td> 8149 <p> 8150 PTR 8151 </p> 8152 </td> 8153<td> 8154 <p> 8155 A pointer to another part of the domain 8156 name space. Described in RFC 1035. 8157 </p> 8158 </td> 8159</tr> 8160<tr> 8161<td> 8162 <p> 8163 PX 8164 </p> 8165 </td> 8166<td> 8167 <p> 8168 Provides mappings between RFC 822 and X.400 8169 addresses. Described in RFC 2163. 8170 </p> 8171 </td> 8172</tr> 8173<tr> 8174<td> 8175 <p> 8176 RP 8177 </p> 8178 </td> 8179<td> 8180 <p> 8181 Information on persons responsible 8182 for the domain. Experimental. Described in RFC 1183. 8183 </p> 8184 </td> 8185</tr> 8186<tr> 8187<td> 8188 <p> 8189 RRSIG 8190 </p> 8191 </td> 8192<td> 8193 <p> 8194 Contains DNSSECbis signature data. Described 8195 in RFC 4034. 8196 </p> 8197 </td> 8198</tr> 8199<tr> 8200<td> 8201 <p> 8202 RT 8203 </p> 8204 </td> 8205<td> 8206 <p> 8207 Route-through binding for hosts that 8208 do not have their own direct wide area network 8209 addresses. 8210 Experimental. Described in RFC 1183. 8211 </p> 8212 </td> 8213</tr> 8214<tr> 8215<td> 8216 <p> 8217 SIG 8218 </p> 8219 </td> 8220<td> 8221 <p> 8222 Contains DNSSEC signature data. Used in 8223 original DNSSEC; replaced by RRSIG in 8224 DNSSECbis, but still used for SIG(0). 8225 Described in RFCs 2535 and 2931. 8226 </p> 8227 </td> 8228</tr> 8229<tr> 8230<td> 8231 <p> 8232 SOA 8233 </p> 8234 </td> 8235<td> 8236 <p> 8237 Identifies the start of a zone of authority. 8238 Described in RFC 1035. 8239 </p> 8240 </td> 8241</tr> 8242<tr> 8243<td> 8244 <p> 8245 SPF 8246 </p> 8247 </td> 8248<td> 8249 <p> 8250 Contains the Sender Policy Framework information 8251 for a given email domain. Described in RFC 4408. 8252 </p> 8253 </td> 8254</tr> 8255<tr> 8256<td> 8257 <p> 8258 SRV 8259 </p> 8260 </td> 8261<td> 8262 <p> 8263 Information about well known network 8264 services (replaces WKS). Described in RFC 2782. 8265 </p> 8266 </td> 8267</tr> 8268<tr> 8269<td> 8270 <p> 8271 SSHFP 8272 </p> 8273 </td> 8274<td> 8275 <p> 8276 Provides a way to securely publish a secure shell key's 8277 fingerprint. Described in RFC 4255. 8278 </p> 8279 </td> 8280</tr> 8281<tr> 8282<td> 8283 <p> 8284 TXT 8285 </p> 8286 </td> 8287<td> 8288 <p> 8289 Text records. Described in RFC 1035. 8290 </p> 8291 </td> 8292</tr> 8293<tr> 8294<td> 8295 <p> 8296 WKS 8297 </p> 8298 </td> 8299<td> 8300 <p> 8301 Information about which well known 8302 network services, such as SMTP, that a domain 8303 supports. Historical. 8304 </p> 8305 </td> 8306</tr> 8307<tr> 8308<td> 8309 <p> 8310 X25 8311 </p> 8312 </td> 8313<td> 8314 <p> 8315 Representation of X.25 network addresses. 8316 Experimental. Described in RFC 1183. 8317 </p> 8318 </td> 8319</tr> 8320</tbody> 8321</table></div> 8322<p> 8323 The following <span class="emphasis"><em>classes</em></span> of resource records 8324 are currently valid in the DNS: 8325 </p> 8326<div class="informaltable"><table border="1"> 8327<colgroup> 8328<col> 8329<col> 8330</colgroup> 8331<tbody> 8332<tr> 8333<td> 8334 <p> 8335 IN 8336 </p> 8337 </td> 8338<td> 8339 <p> 8340 The Internet. 8341 </p> 8342 </td> 8343</tr> 8344<tr> 8345<td> 8346 <p> 8347 CH 8348 </p> 8349 </td> 8350<td> 8351 <p> 8352 Chaosnet, a LAN protocol created at MIT in the 8353 mid-1970s. 8354 Rarely used for its historical purpose, but reused for 8355 BIND's 8356 built-in server information zones, e.g., 8357 <code class="literal">version.bind</code>. 8358 </p> 8359 </td> 8360</tr> 8361<tr> 8362<td> 8363 <p> 8364 HS 8365 </p> 8366 </td> 8367<td> 8368 <p> 8369 Hesiod, an information service 8370 developed by MIT's Project Athena. It is used to share 8371 information 8372 about various systems databases, such as users, 8373 groups, printers 8374 and so on. 8375 </p> 8376 </td> 8377</tr> 8378</tbody> 8379</table></div> 8380<p> 8381 The owner name is often implicit, rather than forming an 8382 integral 8383 part of the RR. For example, many name servers internally form 8384 tree 8385 or hash structures for the name space, and chain RRs off nodes. 8386 The remaining RR parts are the fixed header (type, class, TTL) 8387 which is consistent for all RRs, and a variable part (RDATA) 8388 that 8389 fits the needs of the resource being described. 8390 </p> 8391<p> 8392 The meaning of the TTL field is a time limit on how long an 8393 RR can be kept in a cache. This limit does not apply to 8394 authoritative 8395 data in zones; it is also timed out, but by the refreshing 8396 policies 8397 for the zone. The TTL is assigned by the administrator for the 8398 zone where the data originates. While short TTLs can be used to 8399 minimize caching, and a zero TTL prohibits caching, the 8400 realities 8401 of Internet performance suggest that these times should be on 8402 the 8403 order of days for the typical host. If a change can be 8404 anticipated, 8405 the TTL can be reduced prior to the change to minimize 8406 inconsistency 8407 during the change, and then increased back to its former value 8408 following 8409 the change. 8410 </p> 8411<p> 8412 The data in the RDATA section of RRs is carried as a combination 8413 of binary strings and domain names. The domain names are 8414 frequently 8415 used as "pointers" to other data in the DNS. 8416 </p> 8417</div> 8418<div class="sect3" lang="en"> 8419<div class="titlepage"><div><div><h4 class="title"> 8420<a name="id2596826"></a>Textual expression of RRs</h4></div></div></div> 8421<p> 8422 RRs are represented in binary form in the packets of the DNS 8423 protocol, and are usually represented in highly encoded form 8424 when 8425 stored in a name server or resolver. In the examples provided 8426 in 8427 RFC 1034, a style similar to that used in master files was 8428 employed 8429 in order to show the contents of RRs. In this format, most RRs 8430 are shown on a single line, although continuation lines are 8431 possible 8432 using parentheses. 8433 </p> 8434<p> 8435 The start of the line gives the owner of the RR. If a line 8436 begins with a blank, then the owner is assumed to be the same as 8437 that of the previous RR. Blank lines are often included for 8438 readability. 8439 </p> 8440<p> 8441 Following the owner, we list the TTL, type, and class of the 8442 RR. Class and type use the mnemonics defined above, and TTL is 8443 an integer before the type field. In order to avoid ambiguity 8444 in 8445 parsing, type and class mnemonics are disjoint, TTLs are 8446 integers, 8447 and the type mnemonic is always last. The IN class and TTL 8448 values 8449 are often omitted from examples in the interests of clarity. 8450 </p> 8451<p> 8452 The resource data or RDATA section of the RR are given using 8453 knowledge of the typical representation for the data. 8454 </p> 8455<p> 8456 For example, we might show the RRs carried in a message as: 8457 </p> 8458<div class="informaltable"><table border="1"> 8459<colgroup> 8460<col> 8461<col> 8462<col> 8463</colgroup> 8464<tbody> 8465<tr> 8466<td> 8467 <p> 8468 <code class="literal">ISI.EDU.</code> 8469 </p> 8470 </td> 8471<td> 8472 <p> 8473 <code class="literal">MX</code> 8474 </p> 8475 </td> 8476<td> 8477 <p> 8478 <code class="literal">10 VENERA.ISI.EDU.</code> 8479 </p> 8480 </td> 8481</tr> 8482<tr> 8483<td> 8484 <p></p> 8485 </td> 8486<td> 8487 <p> 8488 <code class="literal">MX</code> 8489 </p> 8490 </td> 8491<td> 8492 <p> 8493 <code class="literal">10 VAXA.ISI.EDU</code> 8494 </p> 8495 </td> 8496</tr> 8497<tr> 8498<td> 8499 <p> 8500 <code class="literal">VENERA.ISI.EDU</code> 8501 </p> 8502 </td> 8503<td> 8504 <p> 8505 <code class="literal">A</code> 8506 </p> 8507 </td> 8508<td> 8509 <p> 8510 <code class="literal">128.9.0.32</code> 8511 </p> 8512 </td> 8513</tr> 8514<tr> 8515<td> 8516 <p></p> 8517 </td> 8518<td> 8519 <p> 8520 <code class="literal">A</code> 8521 </p> 8522 </td> 8523<td> 8524 <p> 8525 <code class="literal">10.1.0.52</code> 8526 </p> 8527 </td> 8528</tr> 8529<tr> 8530<td> 8531 <p> 8532 <code class="literal">VAXA.ISI.EDU</code> 8533 </p> 8534 </td> 8535<td> 8536 <p> 8537 <code class="literal">A</code> 8538 </p> 8539 </td> 8540<td> 8541 <p> 8542 <code class="literal">10.2.0.27</code> 8543 </p> 8544 </td> 8545</tr> 8546<tr> 8547<td> 8548 <p></p> 8549 </td> 8550<td> 8551 <p> 8552 <code class="literal">A</code> 8553 </p> 8554 </td> 8555<td> 8556 <p> 8557 <code class="literal">128.9.0.33</code> 8558 </p> 8559 </td> 8560</tr> 8561</tbody> 8562</table></div> 8563<p> 8564 The MX RRs have an RDATA section which consists of a 16-bit 8565 number followed by a domain name. The address RRs use a 8566 standard 8567 IP address format to contain a 32-bit internet address. 8568 </p> 8569<p> 8570 The above example shows six RRs, with two RRs at each of three 8571 domain names. 8572 </p> 8573<p> 8574 Similarly we might see: 8575 </p> 8576<div class="informaltable"><table border="1"> 8577<colgroup> 8578<col> 8579<col> 8580<col> 8581</colgroup> 8582<tbody> 8583<tr> 8584<td> 8585 <p> 8586 <code class="literal">XX.LCS.MIT.EDU.</code> 8587 </p> 8588 </td> 8589<td> 8590 <p> 8591 <code class="literal">IN A</code> 8592 </p> 8593 </td> 8594<td> 8595 <p> 8596 <code class="literal">10.0.0.44</code> 8597 </p> 8598 </td> 8599</tr> 8600<tr> 8601<td>�</td> 8602<td> 8603 <p> 8604 <code class="literal">CH A</code> 8605 </p> 8606 </td> 8607<td> 8608 <p> 8609 <code class="literal">MIT.EDU. 2420</code> 8610 </p> 8611 </td> 8612</tr> 8613</tbody> 8614</table></div> 8615<p> 8616 This example shows two addresses for 8617 <code class="literal">XX.LCS.MIT.EDU</code>, each of a different class. 8618 </p> 8619</div> 8620</div> 8621<div class="sect2" lang="en"> 8622<div class="titlepage"><div><div><h3 class="title"> 8623<a name="id2597415"></a>Discussion of MX Records</h3></div></div></div> 8624<p> 8625 As described above, domain servers store information as a 8626 series of resource records, each of which contains a particular 8627 piece of information about a given domain name (which is usually, 8628 but not always, a host). The simplest way to think of a RR is as 8629 a typed pair of data, a domain name matched with a relevant datum, 8630 and stored with some additional type information to help systems 8631 determine when the RR is relevant. 8632 </p> 8633<p> 8634 MX records are used to control delivery of email. The data 8635 specified in the record is a priority and a domain name. The 8636 priority 8637 controls the order in which email delivery is attempted, with the 8638 lowest number first. If two priorities are the same, a server is 8639 chosen randomly. If no servers at a given priority are responding, 8640 the mail transport agent will fall back to the next largest 8641 priority. 8642 Priority numbers do not have any absolute meaning — they are 8643 relevant 8644 only respective to other MX records for that domain name. The 8645 domain 8646 name given is the machine to which the mail will be delivered. 8647 It <span class="emphasis"><em>must</em></span> have an associated address record 8648 (A or AAAA) — CNAME is not sufficient. 8649 </p> 8650<p> 8651 For a given domain, if there is both a CNAME record and an 8652 MX record, the MX record is in error, and will be ignored. 8653 Instead, 8654 the mail will be delivered to the server specified in the MX 8655 record 8656 pointed to by the CNAME. 8657 For example: 8658 </p> 8659<div class="informaltable"><table border="1"> 8660<colgroup> 8661<col> 8662<col> 8663<col> 8664<col> 8665<col> 8666</colgroup> 8667<tbody> 8668<tr> 8669<td> 8670 <p> 8671 <code class="literal">example.com.</code> 8672 </p> 8673 </td> 8674<td> 8675 <p> 8676 <code class="literal">IN</code> 8677 </p> 8678 </td> 8679<td> 8680 <p> 8681 <code class="literal">MX</code> 8682 </p> 8683 </td> 8684<td> 8685 <p> 8686 <code class="literal">10</code> 8687 </p> 8688 </td> 8689<td> 8690 <p> 8691 <code class="literal">mail.example.com.</code> 8692 </p> 8693 </td> 8694</tr> 8695<tr> 8696<td> 8697 <p></p> 8698 </td> 8699<td> 8700 <p> 8701 <code class="literal">IN</code> 8702 </p> 8703 </td> 8704<td> 8705 <p> 8706 <code class="literal">MX</code> 8707 </p> 8708 </td> 8709<td> 8710 <p> 8711 <code class="literal">10</code> 8712 </p> 8713 </td> 8714<td> 8715 <p> 8716 <code class="literal">mail2.example.com.</code> 8717 </p> 8718 </td> 8719</tr> 8720<tr> 8721<td> 8722 <p></p> 8723 </td> 8724<td> 8725 <p> 8726 <code class="literal">IN</code> 8727 </p> 8728 </td> 8729<td> 8730 <p> 8731 <code class="literal">MX</code> 8732 </p> 8733 </td> 8734<td> 8735 <p> 8736 <code class="literal">20</code> 8737 </p> 8738 </td> 8739<td> 8740 <p> 8741 <code class="literal">mail.backup.org.</code> 8742 </p> 8743 </td> 8744</tr> 8745<tr> 8746<td> 8747 <p> 8748 <code class="literal">mail.example.com.</code> 8749 </p> 8750 </td> 8751<td> 8752 <p> 8753 <code class="literal">IN</code> 8754 </p> 8755 </td> 8756<td> 8757 <p> 8758 <code class="literal">A</code> 8759 </p> 8760 </td> 8761<td> 8762 <p> 8763 <code class="literal">10.0.0.1</code> 8764 </p> 8765 </td> 8766<td> 8767 <p></p> 8768 </td> 8769</tr> 8770<tr> 8771<td> 8772 <p> 8773 <code class="literal">mail2.example.com.</code> 8774 </p> 8775 </td> 8776<td> 8777 <p> 8778 <code class="literal">IN</code> 8779 </p> 8780 </td> 8781<td> 8782 <p> 8783 <code class="literal">A</code> 8784 </p> 8785 </td> 8786<td> 8787 <p> 8788 <code class="literal">10.0.0.2</code> 8789 </p> 8790 </td> 8791<td> 8792 <p></p> 8793 </td> 8794</tr> 8795</tbody> 8796</table></div> 8797<p> 8798 Mail delivery will be attempted to <code class="literal">mail.example.com</code> and 8799 <code class="literal">mail2.example.com</code> (in 8800 any order), and if neither of those succeed, delivery to <code class="literal">mail.backup.org</code> will 8801 be attempted. 8802 </p> 8803</div> 8804<div class="sect2" lang="en"> 8805<div class="titlepage"><div><div><h3 class="title"> 8806<a name="Setting_TTLs"></a>Setting TTLs</h3></div></div></div> 8807<p> 8808 The time-to-live of the RR field is a 32-bit integer represented 8809 in units of seconds, and is primarily used by resolvers when they 8810 cache RRs. The TTL describes how long a RR can be cached before it 8811 should be discarded. The following three types of TTL are 8812 currently 8813 used in a zone file. 8814 </p> 8815<div class="informaltable"><table border="1"> 8816<colgroup> 8817<col> 8818<col> 8819</colgroup> 8820<tbody> 8821<tr> 8822<td> 8823 <p> 8824 SOA 8825 </p> 8826 </td> 8827<td> 8828 <p> 8829 The last field in the SOA is the negative 8830 caching TTL. This controls how long other servers will 8831 cache no-such-domain 8832 (NXDOMAIN) responses from you. 8833 </p> 8834 <p> 8835 The maximum time for 8836 negative caching is 3 hours (3h). 8837 </p> 8838 </td> 8839</tr> 8840<tr> 8841<td> 8842 <p> 8843 $TTL 8844 </p> 8845 </td> 8846<td> 8847 <p> 8848 The $TTL directive at the top of the 8849 zone file (before the SOA) gives a default TTL for every 8850 RR without 8851 a specific TTL set. 8852 </p> 8853 </td> 8854</tr> 8855<tr> 8856<td> 8857 <p> 8858 RR TTLs 8859 </p> 8860 </td> 8861<td> 8862 <p> 8863 Each RR can have a TTL as the second 8864 field in the RR, which will control how long other 8865 servers can cache 8866 the it. 8867 </p> 8868 </td> 8869</tr> 8870</tbody> 8871</table></div> 8872<p> 8873 All of these TTLs default to units of seconds, though units 8874 can be explicitly specified, for example, <code class="literal">1h30m</code>. 8875 </p> 8876</div> 8877<div class="sect2" lang="en"> 8878<div class="titlepage"><div><div><h3 class="title"> 8879<a name="id2597962"></a>Inverse Mapping in IPv4</h3></div></div></div> 8880<p> 8881 Reverse name resolution (that is, translation from IP address 8882 to name) is achieved by means of the <span class="emphasis"><em>in-addr.arpa</em></span> domain 8883 and PTR records. Entries in the in-addr.arpa domain are made in 8884 least-to-most significant order, read left to right. This is the 8885 opposite order to the way IP addresses are usually written. Thus, 8886 a machine with an IP address of 10.1.2.3 would have a 8887 corresponding 8888 in-addr.arpa name of 8889 3.2.1.10.in-addr.arpa. This name should have a PTR resource record 8890 whose data field is the name of the machine or, optionally, 8891 multiple 8892 PTR records if the machine has more than one name. For example, 8893 in the [<span class="optional">example.com</span>] domain: 8894 </p> 8895<div class="informaltable"><table border="1"> 8896<colgroup> 8897<col> 8898<col> 8899</colgroup> 8900<tbody> 8901<tr> 8902<td> 8903 <p> 8904 <code class="literal">$ORIGIN</code> 8905 </p> 8906 </td> 8907<td> 8908 <p> 8909 <code class="literal">2.1.10.in-addr.arpa</code> 8910 </p> 8911 </td> 8912</tr> 8913<tr> 8914<td> 8915 <p> 8916 <code class="literal">3</code> 8917 </p> 8918 </td> 8919<td> 8920 <p> 8921 <code class="literal">IN PTR foo.example.com.</code> 8922 </p> 8923 </td> 8924</tr> 8925</tbody> 8926</table></div> 8927<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 8928<h3 class="title">Note</h3> 8929<p> 8930 The <span><strong class="command">$ORIGIN</strong></span> lines in the examples 8931 are for providing context to the examples only — they do not 8932 necessarily 8933 appear in the actual usage. They are only used here to indicate 8934 that the example is relative to the listed origin. 8935 </p> 8936</div> 8937</div> 8938<div class="sect2" lang="en"> 8939<div class="titlepage"><div><div><h3 class="title"> 8940<a name="id2598157"></a>Other Zone File Directives</h3></div></div></div> 8941<p> 8942 The Master File Format was initially defined in RFC 1035 and 8943 has subsequently been extended. While the Master File Format 8944 itself 8945 is class independent all records in a Master File must be of the 8946 same 8947 class. 8948 </p> 8949<p> 8950 Master File Directives include <span><strong class="command">$ORIGIN</strong></span>, <span><strong class="command">$INCLUDE</strong></span>, 8951 and <span><strong class="command">$TTL.</strong></span> 8952 </p> 8953<div class="sect3" lang="en"> 8954<div class="titlepage"><div><div><h4 class="title"> 8955<a name="id2598180"></a>The <span><strong class="command">@</strong></span> (at-sign)</h4></div></div></div> 8956<p> 8957 When used in the label (or name) field, the asperand or 8958 at-sign (@) symbol represents the current origin. 8959 At the start of the zone file, it is the 8960 <<code class="varname">zone_name</code>> (followed by 8961 trailing dot). 8962 </p> 8963</div> 8964<div class="sect3" lang="en"> 8965<div class="titlepage"><div><div><h4 class="title"> 8966<a name="id2598196"></a>The <span><strong class="command">$ORIGIN</strong></span> Directive</h4></div></div></div> 8967<p> 8968 Syntax: <span><strong class="command">$ORIGIN</strong></span> 8969 <em class="replaceable"><code>domain-name</code></em> 8970 [<span class="optional"><em class="replaceable"><code>comment</code></em></span>] 8971 </p> 8972<p><span><strong class="command">$ORIGIN</strong></span> 8973 sets the domain name that will be appended to any 8974 unqualified records. When a zone is first read in there 8975 is an implicit <span><strong class="command">$ORIGIN</strong></span> 8976 <<code class="varname">zone_name</code>><span><strong class="command">.</strong></span> 8977 (followed by trailing dot). 8978 The current <span><strong class="command">$ORIGIN</strong></span> is appended to 8979 the domain specified in the <span><strong class="command">$ORIGIN</strong></span> 8980 argument if it is not absolute. 8981 </p> 8982<pre class="programlisting"> 8983$ORIGIN example.com. 8984WWW CNAME MAIN-SERVER 8985</pre> 8986<p> 8987 is equivalent to 8988 </p> 8989<pre class="programlisting"> 8990WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM. 8991</pre> 8992</div> 8993<div class="sect3" lang="en"> 8994<div class="titlepage"><div><div><h4 class="title"> 8995<a name="id2598325"></a>The <span><strong class="command">$INCLUDE</strong></span> Directive</h4></div></div></div> 8996<p> 8997 Syntax: <span><strong class="command">$INCLUDE</strong></span> 8998 <em class="replaceable"><code>filename</code></em> 8999 [<span class="optional"> 9000<em class="replaceable"><code>origin</code></em> </span>] 9001 [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>] 9002 </p> 9003<p> 9004 Read and process the file <code class="filename">filename</code> as 9005 if it were included into the file at this point. If <span><strong class="command">origin</strong></span> is 9006 specified the file is processed with <span><strong class="command">$ORIGIN</strong></span> set 9007 to that value, otherwise the current <span><strong class="command">$ORIGIN</strong></span> is 9008 used. 9009 </p> 9010<p> 9011 The origin and the current domain name 9012 revert to the values they had prior to the <span><strong class="command">$INCLUDE</strong></span> once 9013 the file has been read. 9014 </p> 9015<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 9016<h3 class="title">Note</h3> 9017<p> 9018 RFC 1035 specifies that the current origin should be restored 9019 after 9020 an <span><strong class="command">$INCLUDE</strong></span>, but it is silent 9021 on whether the current 9022 domain name should also be restored. BIND 9 restores both of 9023 them. 9024 This could be construed as a deviation from RFC 1035, a 9025 feature, or both. 9026 </p> 9027</div> 9028</div> 9029<div class="sect3" lang="en"> 9030<div class="titlepage"><div><div><h4 class="title"> 9031<a name="id2598394"></a>The <span><strong class="command">$TTL</strong></span> Directive</h4></div></div></div> 9032<p> 9033 Syntax: <span><strong class="command">$TTL</strong></span> 9034 <em class="replaceable"><code>default-ttl</code></em> 9035 [<span class="optional"> 9036<em class="replaceable"><code>comment</code></em> </span>] 9037 </p> 9038<p> 9039 Set the default Time To Live (TTL) for subsequent records 9040 with undefined TTLs. Valid TTLs are of the range 0-2147483647 9041 seconds. 9042 </p> 9043<p><span><strong class="command">$TTL</strong></span> 9044 is defined in RFC 2308. 9045 </p> 9046</div> 9047</div> 9048<div class="sect2" lang="en"> 9049<div class="titlepage"><div><div><h3 class="title"> 9050<a name="id2598430"></a><acronym class="acronym">BIND</acronym> Master File Extension: the <span><strong class="command">$GENERATE</strong></span> Directive</h3></div></div></div> 9051<p> 9052 Syntax: <span><strong class="command">$GENERATE</strong></span> 9053 <em class="replaceable"><code>range</code></em> 9054 <em class="replaceable"><code>lhs</code></em> 9055 [<span class="optional"><em class="replaceable"><code>ttl</code></em></span>] 9056 [<span class="optional"><em class="replaceable"><code>class</code></em></span>] 9057 <em class="replaceable"><code>type</code></em> 9058 <em class="replaceable"><code>rhs</code></em> 9059 [<span class="optional"><em class="replaceable"><code>comment</code></em></span>] 9060 </p> 9061<p><span><strong class="command">$GENERATE</strong></span> 9062 is used to create a series of resource records that only 9063 differ from each other by an 9064 iterator. <span><strong class="command">$GENERATE</strong></span> can be used to 9065 easily generate the sets of records required to support 9066 sub /24 reverse delegations described in RFC 2317: 9067 Classless IN-ADDR.ARPA delegation. 9068 </p> 9069<pre class="programlisting">$ORIGIN 0.0.192.IN-ADDR.ARPA. 9070$GENERATE 1-2 @ NS SERVER$.EXAMPLE. 9071$GENERATE 1-127 $ CNAME $.0</pre> 9072<p> 9073 is equivalent to 9074 </p> 9075<pre class="programlisting">0.0.0.192.IN-ADDR.ARPA. NS SERVER1.EXAMPLE. 90760.0.0.192.IN-ADDR.ARPA. NS SERVER2.EXAMPLE. 90771.0.0.192.IN-ADDR.ARPA. CNAME 1.0.0.0.192.IN-ADDR.ARPA. 90782.0.0.192.IN-ADDR.ARPA. CNAME 2.0.0.0.192.IN-ADDR.ARPA. 9079... 9080127.0.0.192.IN-ADDR.ARPA. CNAME 127.0.0.0.192.IN-ADDR.ARPA. 9081</pre> 9082<p> 9083 Generate a set of A and MX records. Note the MX's right hand 9084 side is a quoted string. The quotes will be stripped when the 9085 right hand side is processed. 9086 </p> 9087<pre class="programlisting"> 9088$ORIGIN EXAMPLE. 9089$GENERATE 1-127 HOST-$ A 1.2.3.$ 9090$GENERATE 1-127 HOST-$ MX "0 ."</pre> 9091<p> 9092 is equivalent to 9093 </p> 9094<pre class="programlisting">HOST-1.EXAMPLE. A 1.2.3.1 9095HOST-1.EXAMPLE. MX 0 . 9096HOST-2.EXAMPLE. A 1.2.3.2 9097HOST-2.EXAMPLE. MX 0 . 9098HOST-3.EXAMPLE. A 1.2.3.3 9099HOST-3.EXAMPLE. MX 0 . 9100... 9101HOST-127.EXAMPLE. A 1.2.3.127 9102HOST-127.EXAMPLE. MX 0 . 9103</pre> 9104<div class="informaltable"><table border="1"> 9105<colgroup> 9106<col> 9107<col> 9108</colgroup> 9109<tbody> 9110<tr> 9111<td> 9112 <p><span><strong class="command">range</strong></span></p> 9113 </td> 9114<td> 9115 <p> 9116 This can be one of two forms: start-stop 9117 or start-stop/step. If the first form is used, then step 9118 is set to 9119 1. All of start, stop and step must be positive. 9120 </p> 9121 </td> 9122</tr> 9123<tr> 9124<td> 9125 <p><span><strong class="command">lhs</strong></span></p> 9126 </td> 9127<td> 9128 <p>This 9129 describes the owner name of the resource records 9130 to be created. Any single <span><strong class="command">$</strong></span> 9131 (dollar sign) 9132 symbols within the <span><strong class="command">lhs</strong></span> string 9133 are replaced by the iterator value. 9134 9135 To get a $ in the output, you need to escape the 9136 <span><strong class="command">$</strong></span> using a backslash 9137 <span><strong class="command">\</strong></span>, 9138 e.g. <span><strong class="command">\$</strong></span>. The 9139 <span><strong class="command">$</strong></span> may optionally be followed 9140 by modifiers which change the offset from the 9141 iterator, field width and base. 9142 9143 Modifiers are introduced by a 9144 <span><strong class="command">{</strong></span> (left brace) immediately following the 9145 <span><strong class="command">$</strong></span> as 9146 <span><strong class="command">${offset[,width[,base]]}</strong></span>. 9147 For example, <span><strong class="command">${-20,3,d}</strong></span> 9148 subtracts 20 from the current value, prints the 9149 result as a decimal in a zero-padded field of 9150 width 3. 9151 9152 Available output forms are decimal 9153 (<span><strong class="command">d</strong></span>), octal 9154 (<span><strong class="command">o</strong></span>), hexadecimal 9155 (<span><strong class="command">x</strong></span> or <span><strong class="command">X</strong></span> 9156 for uppercase) and nibble 9157 (<span><strong class="command">n</strong></span> or <span><strong class="command">N</strong></span>\ 9158 for uppercase). The default modifier is 9159 <span><strong class="command">${0,0,d}</strong></span>. If the 9160 <span><strong class="command">lhs</strong></span> is not absolute, the 9161 current <span><strong class="command">$ORIGIN</strong></span> is appended 9162 to the name. 9163 </p> 9164 <p> 9165 In nibble mode the value will be treated as 9166 if it was a reversed hexadecimal string 9167 with each hexadecimal digit as a separate 9168 label. The width field includes the label 9169 separator. 9170 </p> 9171 <p> 9172 For compatibility with earlier versions, 9173 <span><strong class="command">$$</strong></span> is still recognized as 9174 indicating a literal $ in the output. 9175 </p> 9176 </td> 9177</tr> 9178<tr> 9179<td> 9180 <p><span><strong class="command">ttl</strong></span></p> 9181 </td> 9182<td> 9183 <p> 9184 Specifies the time-to-live of the generated records. If 9185 not specified this will be inherited using the 9186 normal TTL inheritance rules. 9187 </p> 9188 <p><span><strong class="command">class</strong></span> 9189 and <span><strong class="command">ttl</strong></span> can be 9190 entered in either order. 9191 </p> 9192 </td> 9193</tr> 9194<tr> 9195<td> 9196 <p><span><strong class="command">class</strong></span></p> 9197 </td> 9198<td> 9199 <p> 9200 Specifies the class of the generated records. 9201 This must match the zone class if it is 9202 specified. 9203 </p> 9204 <p><span><strong class="command">class</strong></span> 9205 and <span><strong class="command">ttl</strong></span> can be 9206 entered in either order. 9207 </p> 9208 </td> 9209</tr> 9210<tr> 9211<td> 9212 <p><span><strong class="command">type</strong></span></p> 9213 </td> 9214<td> 9215 <p> 9216 Any valid type. 9217 </p> 9218 </td> 9219</tr> 9220<tr> 9221<td> 9222 <p><span><strong class="command">rhs</strong></span></p> 9223 </td> 9224<td> 9225 <p> 9226 <span><strong class="command">rhs</strong></span>, optionally, quoted string. 9227 </p> 9228 </td> 9229</tr> 9230</tbody> 9231</table></div> 9232<p> 9233 The <span><strong class="command">$GENERATE</strong></span> directive is a <acronym class="acronym">BIND</acronym> extension 9234 and not part of the standard zone file format. 9235 </p> 9236<p> 9237 BIND 8 does not support the optional TTL and CLASS fields. 9238 </p> 9239</div> 9240<div class="sect2" lang="en"> 9241<div class="titlepage"><div><div><h3 class="title"> 9242<a name="zonefile_format"></a>Additional File Formats</h3></div></div></div> 9243<p> 9244 In addition to the standard textual format, BIND 9 9245 supports the ability to read or dump to zone files in 9246 other formats. The <code class="constant">raw</code> format is 9247 currently available as an additional format. It is a 9248 binary format representing BIND 9's internal data 9249 structure directly, thereby remarkably improving the 9250 loading time. 9251 </p> 9252<p> 9253 For a primary server, a zone file in the 9254 <code class="constant">raw</code> format is expected to be 9255 generated from a textual zone file by the 9256 <span><strong class="command">named-compilezone</strong></span> command. For a 9257 secondary server or for a dynamic zone, it is automatically 9258 generated (if this format is specified by the 9259 <span><strong class="command">masterfile-format</strong></span> option) when 9260 <span><strong class="command">named</strong></span> dumps the zone contents after 9261 zone transfer or when applying prior updates. 9262 </p> 9263<p> 9264 If a zone file in a binary format needs manual modification, 9265 it first must be converted to a textual form by the 9266 <span><strong class="command">named-compilezone</strong></span> command. All 9267 necessary modification should go to the text file, which 9268 should then be converted to the binary form by the 9269 <span><strong class="command">named-compilezone</strong></span> command again. 9270 </p> 9271<p> 9272 Although the <code class="constant">raw</code> format uses the 9273 network byte order and avoids architecture-dependent 9274 data alignment so that it is as much portable as 9275 possible, it is primarily expected to be used inside 9276 the same single system. In order to export a zone 9277 file in the <code class="constant">raw</code> format or make a 9278 portable backup of the file, it is recommended to 9279 convert the file to the standard textual representation. 9280 </p> 9281</div> 9282</div> 9283<div class="sect1" lang="en"> 9284<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 9285<a name="statistics"></a>BIND9 Statistics</h2></div></div></div> 9286<p> 9287 <acronym class="acronym">BIND</acronym> 9 maintains lots of statistics 9288 information and provides several interfaces for users to 9289 get access to the statistics. 9290 The available statistics include all statistics counters 9291 that were available in <acronym class="acronym">BIND</acronym> 8 and 9292 are meaningful in <acronym class="acronym">BIND</acronym> 9, 9293 and other information that is considered useful. 9294 </p> 9295<p> 9296 The statistics information is categorized into the following 9297 sections. 9298 </p> 9299<div class="informaltable"><table border="1"> 9300<colgroup> 9301<col> 9302<col> 9303</colgroup> 9304<tbody> 9305<tr> 9306<td> 9307 <p>Incoming Requests</p> 9308 </td> 9309<td> 9310 <p> 9311 The number of incoming DNS requests for each OPCODE. 9312 </p> 9313 </td> 9314</tr> 9315<tr> 9316<td> 9317 <p>Incoming Queries</p> 9318 </td> 9319<td> 9320 <p> 9321 The number of incoming queries for each RR type. 9322 </p> 9323 </td> 9324</tr> 9325<tr> 9326<td> 9327 <p>Outgoing Queries</p> 9328 </td> 9329<td> 9330 <p> 9331 The number of outgoing queries for each RR 9332 type sent from the internal resolver. 9333 Maintained per view. 9334 </p> 9335 </td> 9336</tr> 9337<tr> 9338<td> 9339 <p>Name Server Statistics</p> 9340 </td> 9341<td> 9342 <p> 9343 Statistics counters about incoming request processing. 9344 </p> 9345 </td> 9346</tr> 9347<tr> 9348<td> 9349 <p>Zone Maintenance Statistics</p> 9350 </td> 9351<td> 9352 <p> 9353 Statistics counters regarding zone maintenance 9354 operations such as zone transfers. 9355 </p> 9356 </td> 9357</tr> 9358<tr> 9359<td> 9360 <p>Resolver Statistics</p> 9361 </td> 9362<td> 9363 <p> 9364 Statistics counters about name resolution 9365 performed in the internal resolver. 9366 Maintained per view. 9367 </p> 9368 </td> 9369</tr> 9370<tr> 9371<td> 9372 <p>Cache DB RRsets</p> 9373 </td> 9374<td> 9375 <p> 9376 The number of RRsets per RR type and nonexistent 9377 names stored in the cache database. 9378 If the exclamation mark (!) is printed for a RR 9379 type, it means that particular type of RRset is 9380 known to be nonexistent (this is also known as 9381 "NXRRSET"). 9382 Maintained per view. 9383 </p> 9384 </td> 9385</tr> 9386<tr> 9387<td> 9388 <p>Socket I/O Statistics</p> 9389 </td> 9390<td> 9391 <p> 9392 Statistics counters about network related events. 9393 </p> 9394 </td> 9395</tr> 9396</tbody> 9397</table></div> 9398<p> 9399 A subset of Name Server Statistics is collected and shown 9400 per zone for which the server has the authority when 9401 <span><strong class="command">zone-statistics</strong></span> is set to 9402 <strong class="userinput"><code>yes</code></strong>. 9403 These statistics counters are shown with their zone and view 9404 names. 9405 In some cases the view names are omitted for the default view. 9406 </p> 9407<p> 9408 There are currently two user interfaces to get access to the 9409 statistics. 9410 One is in the plain text format dumped to the file specified 9411 by the <span><strong class="command">statistics-file</strong></span> configuration option. 9412 The other is remotely accessible via a statistics channel 9413 when the <span><strong class="command">statistics-channels</strong></span> statement 9414 is specified in the configuration file 9415 (see <a href="Bv9ARM.ch06.html#statschannels" title="statistics-channels Statement Grammar">the section called “<span><strong class="command">statistics-channels</strong></span> Statement Grammar”</a>.) 9416 </p> 9417<div class="sect3" lang="en"> 9418<div class="titlepage"><div><div><h4 class="title"> 9419<a name="statsfile"></a>The Statistics File</h4></div></div></div> 9420<p> 9421 The text format statistics dump begins with a line, like: 9422 </p> 9423<p> 9424 <span><strong class="command">+++ Statistics Dump +++ (973798949)</strong></span> 9425 </p> 9426<p> 9427 The number in parentheses is a standard 9428 Unix-style timestamp, measured as seconds since January 1, 1970. 9429 9430 Following 9431 that line is a set of statistics information, which is categorized 9432 as described above. 9433 Each section begins with a line, like: 9434 </p> 9435<p> 9436 <span><strong class="command">++ Name Server Statistics ++</strong></span> 9437 </p> 9438<p> 9439 Each section consists of lines, each containing the statistics 9440 counter value followed by its textual description. 9441 See below for available counters. 9442 For brevity, counters that have a value of 0 are not shown 9443 in the statistics file. 9444 </p> 9445<p> 9446 The statistics dump ends with the line where the 9447 number is identical to the number in the beginning line; for example: 9448 </p> 9449<p> 9450 <span><strong class="command">--- Statistics Dump --- (973798949)</strong></span> 9451 </p> 9452</div> 9453<div class="sect2" lang="en"> 9454<div class="titlepage"><div><div><h3 class="title"> 9455<a name="statistics_counters"></a>Statistics Counters</h3></div></div></div> 9456<p> 9457 The following tables summarize statistics counters that 9458 <acronym class="acronym">BIND</acronym> 9 provides. 9459 For each row of the tables, the leftmost column is the 9460 abbreviated symbol name of that counter. 9461 These symbols are shown in the statistics information 9462 accessed via an HTTP statistics channel. 9463 The rightmost column gives the description of the counter, 9464 which is also shown in the statistics file 9465 (but, in this document, possibly with slight modification 9466 for better readability). 9467 Additional notes may also be provided in this column. 9468 When a middle column exists between these two columns, 9469 it gives the corresponding counter name of the 9470 <acronym class="acronym">BIND</acronym> 8 statistics, if applicable. 9471 </p> 9472<div class="sect3" lang="en"> 9473<div class="titlepage"><div><div><h4 class="title"> 9474<a name="id2599384"></a>Name Server Statistics Counters</h4></div></div></div> 9475<div class="informaltable"><table border="1"> 9476<colgroup> 9477<col> 9478<col> 9479<col> 9480</colgroup> 9481<tbody> 9482<tr> 9483<td> 9484 <p> 9485 <span class="emphasis"><em>Symbol</em></span> 9486 </p> 9487 </td> 9488<td> 9489 <p> 9490 <span class="emphasis"><em>BIND8 Symbol</em></span> 9491 </p> 9492 </td> 9493<td> 9494 <p> 9495 <span class="emphasis"><em>Description</em></span> 9496 </p> 9497 </td> 9498</tr> 9499<tr> 9500<td> 9501 <p><span><strong class="command">Requestv4</strong></span></p> 9502 </td> 9503<td> 9504 <p><span><strong class="command">RQ</strong></span></p> 9505 </td> 9506<td> 9507 <p> 9508 IPv4 requests received. 9509 Note: this also counts non query requests. 9510 </p> 9511 </td> 9512</tr> 9513<tr> 9514<td> 9515 <p><span><strong class="command">Requestv6</strong></span></p> 9516 </td> 9517<td> 9518 <p><span><strong class="command">RQ</strong></span></p> 9519 </td> 9520<td> 9521 <p> 9522 IPv6 requests received. 9523 Note: this also counts non query requests. 9524 </p> 9525 </td> 9526</tr> 9527<tr> 9528<td> 9529 <p><span><strong class="command">ReqEdns0</strong></span></p> 9530 </td> 9531<td> 9532 <p><span><strong class="command"></strong></span></p> 9533 </td> 9534<td> 9535 <p> 9536 Requests with EDNS(0) received. 9537 </p> 9538 </td> 9539</tr> 9540<tr> 9541<td> 9542 <p><span><strong class="command">ReqBadEDNSVer</strong></span></p> 9543 </td> 9544<td> 9545 <p><span><strong class="command"></strong></span></p> 9546 </td> 9547<td> 9548 <p> 9549 Requests with unsupported EDNS version received. 9550 </p> 9551 </td> 9552</tr> 9553<tr> 9554<td> 9555 <p><span><strong class="command">ReqTSIG</strong></span></p> 9556 </td> 9557<td> 9558 <p><span><strong class="command"></strong></span></p> 9559 </td> 9560<td> 9561 <p> 9562 Requests with TSIG received. 9563 </p> 9564 </td> 9565</tr> 9566<tr> 9567<td> 9568 <p><span><strong class="command">ReqSIG0</strong></span></p> 9569 </td> 9570<td> 9571 <p><span><strong class="command"></strong></span></p> 9572 </td> 9573<td> 9574 <p> 9575 Requests with SIG(0) received. 9576 </p> 9577 </td> 9578</tr> 9579<tr> 9580<td> 9581 <p><span><strong class="command">ReqBadSIG</strong></span></p> 9582 </td> 9583<td> 9584 <p><span><strong class="command"></strong></span></p> 9585 </td> 9586<td> 9587 <p> 9588 Requests with invalid (TSIG or SIG(0)) signature. 9589 </p> 9590 </td> 9591</tr> 9592<tr> 9593<td> 9594 <p><span><strong class="command">ReqTCP</strong></span></p> 9595 </td> 9596<td> 9597 <p><span><strong class="command">RTCP</strong></span></p> 9598 </td> 9599<td> 9600 <p> 9601 TCP requests received. 9602 </p> 9603 </td> 9604</tr> 9605<tr> 9606<td> 9607 <p><span><strong class="command">AuthQryRej</strong></span></p> 9608 </td> 9609<td> 9610 <p><span><strong class="command">RUQ</strong></span></p> 9611 </td> 9612<td> 9613 <p> 9614 Authoritative (non recursive) queries rejected. 9615 </p> 9616 </td> 9617</tr> 9618<tr> 9619<td> 9620 <p><span><strong class="command">RecQryRej</strong></span></p> 9621 </td> 9622<td> 9623 <p><span><strong class="command">RURQ</strong></span></p> 9624 </td> 9625<td> 9626 <p> 9627 Recursive queries rejected. 9628 </p> 9629 </td> 9630</tr> 9631<tr> 9632<td> 9633 <p><span><strong class="command">XfrRej</strong></span></p> 9634 </td> 9635<td> 9636 <p><span><strong class="command">RUXFR</strong></span></p> 9637 </td> 9638<td> 9639 <p> 9640 Zone transfer requests rejected. 9641 </p> 9642 </td> 9643</tr> 9644<tr> 9645<td> 9646 <p><span><strong class="command">UpdateRej</strong></span></p> 9647 </td> 9648<td> 9649 <p><span><strong class="command">RUUpd</strong></span></p> 9650 </td> 9651<td> 9652 <p> 9653 Dynamic update requests rejected. 9654 </p> 9655 </td> 9656</tr> 9657<tr> 9658<td> 9659 <p><span><strong class="command">Response</strong></span></p> 9660 </td> 9661<td> 9662 <p><span><strong class="command">SAns</strong></span></p> 9663 </td> 9664<td> 9665 <p> 9666 Responses sent. 9667 </p> 9668 </td> 9669</tr> 9670<tr> 9671<td> 9672 <p><span><strong class="command">RespTruncated</strong></span></p> 9673 </td> 9674<td> 9675 <p><span><strong class="command"></strong></span></p> 9676 </td> 9677<td> 9678 <p> 9679 Truncated responses sent. 9680 </p> 9681 </td> 9682</tr> 9683<tr> 9684<td> 9685 <p><span><strong class="command">RespEDNS0</strong></span></p> 9686 </td> 9687<td> 9688 <p><span><strong class="command"></strong></span></p> 9689 </td> 9690<td> 9691 <p> 9692 Responses with EDNS(0) sent. 9693 </p> 9694 </td> 9695</tr> 9696<tr> 9697<td> 9698 <p><span><strong class="command">RespTSIG</strong></span></p> 9699 </td> 9700<td> 9701 <p><span><strong class="command"></strong></span></p> 9702 </td> 9703<td> 9704 <p> 9705 Responses with TSIG sent. 9706 </p> 9707 </td> 9708</tr> 9709<tr> 9710<td> 9711 <p><span><strong class="command">RespSIG0</strong></span></p> 9712 </td> 9713<td> 9714 <p><span><strong class="command"></strong></span></p> 9715 </td> 9716<td> 9717 <p> 9718 Responses with SIG(0) sent. 9719 </p> 9720 </td> 9721</tr> 9722<tr> 9723<td> 9724 <p><span><strong class="command">QrySuccess</strong></span></p> 9725 </td> 9726<td> 9727 <p><span><strong class="command"></strong></span></p> 9728 </td> 9729<td> 9730 <p> 9731 Queries resulted in a successful answer. 9732 This means the query which returns a NOERROR response 9733 with at least one answer RR. 9734 This corresponds to the 9735 <span><strong class="command">success</strong></span> counter 9736 of previous versions of 9737 <acronym class="acronym">BIND</acronym> 9. 9738 </p> 9739 </td> 9740</tr> 9741<tr> 9742<td> 9743 <p><span><strong class="command">QryAuthAns</strong></span></p> 9744 </td> 9745<td> 9746 <p><span><strong class="command"></strong></span></p> 9747 </td> 9748<td> 9749 <p> 9750 Queries resulted in authoritative answer. 9751 </p> 9752 </td> 9753</tr> 9754<tr> 9755<td> 9756 <p><span><strong class="command">QryNoauthAns</strong></span></p> 9757 </td> 9758<td> 9759 <p><span><strong class="command">SNaAns</strong></span></p> 9760 </td> 9761<td> 9762 <p> 9763 Queries resulted in non authoritative answer. 9764 </p> 9765 </td> 9766</tr> 9767<tr> 9768<td> 9769 <p><span><strong class="command">QryReferral</strong></span></p> 9770 </td> 9771<td> 9772 <p><span><strong class="command"></strong></span></p> 9773 </td> 9774<td> 9775 <p> 9776 Queries resulted in referral answer. 9777 This corresponds to the 9778 <span><strong class="command">referral</strong></span> counter 9779 of previous versions of 9780 <acronym class="acronym">BIND</acronym> 9. 9781 </p> 9782 </td> 9783</tr> 9784<tr> 9785<td> 9786 <p><span><strong class="command">QryNxrrset</strong></span></p> 9787 </td> 9788<td> 9789 <p><span><strong class="command"></strong></span></p> 9790 </td> 9791<td> 9792 <p> 9793 Queries resulted in NOERROR responses with no data. 9794 This corresponds to the 9795 <span><strong class="command">nxrrset</strong></span> counter 9796 of previous versions of 9797 <acronym class="acronym">BIND</acronym> 9. 9798 </p> 9799 </td> 9800</tr> 9801<tr> 9802<td> 9803 <p><span><strong class="command">QrySERVFAIL</strong></span></p> 9804 </td> 9805<td> 9806 <p><span><strong class="command">SFail</strong></span></p> 9807 </td> 9808<td> 9809 <p> 9810 Queries resulted in SERVFAIL. 9811 </p> 9812 </td> 9813</tr> 9814<tr> 9815<td> 9816 <p><span><strong class="command">QryFORMERR</strong></span></p> 9817 </td> 9818<td> 9819 <p><span><strong class="command">SFErr</strong></span></p> 9820 </td> 9821<td> 9822 <p> 9823 Queries resulted in FORMERR. 9824 </p> 9825 </td> 9826</tr> 9827<tr> 9828<td> 9829 <p><span><strong class="command">QryNXDOMAIN</strong></span></p> 9830 </td> 9831<td> 9832 <p><span><strong class="command">SNXD</strong></span></p> 9833 </td> 9834<td> 9835 <p> 9836 Queries resulted in NXDOMAIN. 9837 This corresponds to the 9838 <span><strong class="command">nxdomain</strong></span> counter 9839 of previous versions of 9840 <acronym class="acronym">BIND</acronym> 9. 9841 </p> 9842 </td> 9843</tr> 9844<tr> 9845<td> 9846 <p><span><strong class="command">QryRecursion</strong></span></p> 9847 </td> 9848<td> 9849 <p><span><strong class="command">RFwdQ</strong></span></p> 9850 </td> 9851<td> 9852 <p> 9853 Queries which caused the server 9854 to perform recursion in order to find the final answer. 9855 This corresponds to the 9856 <span><strong class="command">recursion</strong></span> counter 9857 of previous versions of 9858 <acronym class="acronym">BIND</acronym> 9. 9859 </p> 9860 </td> 9861</tr> 9862<tr> 9863<td> 9864 <p><span><strong class="command">QryDuplicate</strong></span></p> 9865 </td> 9866<td> 9867 <p><span><strong class="command">RDupQ</strong></span></p> 9868 </td> 9869<td> 9870 <p> 9871 Queries which the server attempted to 9872 recurse but discovered an existing query with the same 9873 IP address, port, query ID, name, type and class 9874 already being processed. 9875 This corresponds to the 9876 <span><strong class="command">duplicate</strong></span> counter 9877 of previous versions of 9878 <acronym class="acronym">BIND</acronym> 9. 9879 </p> 9880 </td> 9881</tr> 9882<tr> 9883<td> 9884 <p><span><strong class="command">QryDropped</strong></span></p> 9885 </td> 9886<td> 9887 <p><span><strong class="command"></strong></span></p> 9888 </td> 9889<td> 9890 <p> 9891 Recursive queries for which the server 9892 discovered an excessive number of existing 9893 recursive queries for the same name, type and 9894 class and were subsequently dropped. 9895 This is the number of dropped queries due to 9896 the reason explained with the 9897 <span><strong class="command">clients-per-query</strong></span> 9898 and 9899 <span><strong class="command">max-clients-per-query</strong></span> 9900 options 9901 (see the description about 9902 <a href="Bv9ARM.ch06.html#clients-per-query"><span><strong class="command">clients-per-query</strong></span></a>.) 9903 This corresponds to the 9904 <span><strong class="command">dropped</strong></span> counter 9905 of previous versions of 9906 <acronym class="acronym">BIND</acronym> 9. 9907 </p> 9908 </td> 9909</tr> 9910<tr> 9911<td> 9912 <p><span><strong class="command">QryFailure</strong></span></p> 9913 </td> 9914<td> 9915 <p><span><strong class="command"></strong></span></p> 9916 </td> 9917<td> 9918 <p> 9919 Other query failures. 9920 This corresponds to the 9921 <span><strong class="command">failure</strong></span> counter 9922 of previous versions of 9923 <acronym class="acronym">BIND</acronym> 9. 9924 Note: this counter is provided mainly for 9925 backward compatibility with the previous versions. 9926 Normally a more fine-grained counters such as 9927 <span><strong class="command">AuthQryRej</strong></span> and 9928 <span><strong class="command">RecQryRej</strong></span> 9929 that would also fall into this counter are provided, 9930 and so this counter would not be of much 9931 interest in practice. 9932 </p> 9933 </td> 9934</tr> 9935<tr> 9936<td> 9937 <p><span><strong class="command">XfrReqDone</strong></span></p> 9938 </td> 9939<td> 9940 <p><span><strong class="command"></strong></span></p> 9941 </td> 9942<td> 9943 <p> 9944 Requested zone transfers completed. 9945 </p> 9946 </td> 9947</tr> 9948<tr> 9949<td> 9950 <p><span><strong class="command">UpdateReqFwd</strong></span></p> 9951 </td> 9952<td> 9953 <p><span><strong class="command"></strong></span></p> 9954 </td> 9955<td> 9956 <p> 9957 Update requests forwarded. 9958 </p> 9959 </td> 9960</tr> 9961<tr> 9962<td> 9963 <p><span><strong class="command">UpdateRespFwd</strong></span></p> 9964 </td> 9965<td> 9966 <p><span><strong class="command"></strong></span></p> 9967 </td> 9968<td> 9969 <p> 9970 Update responses forwarded. 9971 </p> 9972 </td> 9973</tr> 9974<tr> 9975<td> 9976 <p><span><strong class="command">UpdateFwdFail</strong></span></p> 9977 </td> 9978<td> 9979 <p><span><strong class="command"></strong></span></p> 9980 </td> 9981<td> 9982 <p> 9983 Dynamic update forward failed. 9984 </p> 9985 </td> 9986</tr> 9987<tr> 9988<td> 9989 <p><span><strong class="command">UpdateDone</strong></span></p> 9990 </td> 9991<td> 9992 <p><span><strong class="command"></strong></span></p> 9993 </td> 9994<td> 9995 <p> 9996 Dynamic updates completed. 9997 </p> 9998 </td> 9999</tr> 10000<tr> 10001<td> 10002 <p><span><strong class="command">UpdateFail</strong></span></p> 10003 </td> 10004<td> 10005 <p><span><strong class="command"></strong></span></p> 10006 </td> 10007<td> 10008 <p> 10009 Dynamic updates failed. 10010 </p> 10011 </td> 10012</tr> 10013<tr> 10014<td> 10015 <p><span><strong class="command">UpdateBadPrereq</strong></span></p> 10016 </td> 10017<td> 10018 <p><span><strong class="command"></strong></span></p> 10019 </td> 10020<td> 10021 <p> 10022 Dynamic updates rejected due to prerequisite failure. 10023 </p> 10024 </td> 10025</tr> 10026</tbody> 10027</table></div> 10028</div> 10029<div class="sect3" lang="en"> 10030<div class="titlepage"><div><div><h4 class="title"> 10031<a name="id2600857"></a>Zone Maintenance Statistics Counters</h4></div></div></div> 10032<div class="informaltable"><table border="1"> 10033<colgroup> 10034<col> 10035<col> 10036</colgroup> 10037<tbody> 10038<tr> 10039<td> 10040 <p> 10041 <span class="emphasis"><em>Symbol</em></span> 10042 </p> 10043 </td> 10044<td> 10045 <p> 10046 <span class="emphasis"><em>Description</em></span> 10047 </p> 10048 </td> 10049</tr> 10050<tr> 10051<td> 10052 <p><span><strong class="command">NotifyOutv4</strong></span></p> 10053 </td> 10054<td> 10055 <p> 10056 IPv4 notifies sent. 10057 </p> 10058 </td> 10059</tr> 10060<tr> 10061<td> 10062 <p><span><strong class="command">NotifyOutv6</strong></span></p> 10063 </td> 10064<td> 10065 <p> 10066 IPv6 notifies sent. 10067 </p> 10068 </td> 10069</tr> 10070<tr> 10071<td> 10072 <p><span><strong class="command">NotifyInv4</strong></span></p> 10073 </td> 10074<td> 10075 <p> 10076 IPv4 notifies received. 10077 </p> 10078 </td> 10079</tr> 10080<tr> 10081<td> 10082 <p><span><strong class="command">NotifyInv6</strong></span></p> 10083 </td> 10084<td> 10085 <p> 10086 IPv6 notifies received. 10087 </p> 10088 </td> 10089</tr> 10090<tr> 10091<td> 10092 <p><span><strong class="command">NotifyRej</strong></span></p> 10093 </td> 10094<td> 10095 <p> 10096 Incoming notifies rejected. 10097 </p> 10098 </td> 10099</tr> 10100<tr> 10101<td> 10102 <p><span><strong class="command">SOAOutv4</strong></span></p> 10103 </td> 10104<td> 10105 <p> 10106 IPv4 SOA queries sent. 10107 </p> 10108 </td> 10109</tr> 10110<tr> 10111<td> 10112 <p><span><strong class="command">SOAOutv6</strong></span></p> 10113 </td> 10114<td> 10115 <p> 10116 IPv6 SOA queries sent. 10117 </p> 10118 </td> 10119</tr> 10120<tr> 10121<td> 10122 <p><span><strong class="command">AXFRReqv4</strong></span></p> 10123 </td> 10124<td> 10125 <p> 10126 IPv4 AXFR requested. 10127 </p> 10128 </td> 10129</tr> 10130<tr> 10131<td> 10132 <p><span><strong class="command">AXFRReqv6</strong></span></p> 10133 </td> 10134<td> 10135 <p> 10136 IPv6 AXFR requested. 10137 </p> 10138 </td> 10139</tr> 10140<tr> 10141<td> 10142 <p><span><strong class="command">IXFRReqv4</strong></span></p> 10143 </td> 10144<td> 10145 <p> 10146 IPv4 IXFR requested. 10147 </p> 10148 </td> 10149</tr> 10150<tr> 10151<td> 10152 <p><span><strong class="command">IXFRReqv6</strong></span></p> 10153 </td> 10154<td> 10155 <p> 10156 IPv6 IXFR requested. 10157 </p> 10158 </td> 10159</tr> 10160<tr> 10161<td> 10162 <p><span><strong class="command">XfrSuccess</strong></span></p> 10163 </td> 10164<td> 10165 <p> 10166 Zone transfer requests succeeded. 10167 </p> 10168 </td> 10169</tr> 10170<tr> 10171<td> 10172 <p><span><strong class="command">XfrFail</strong></span></p> 10173 </td> 10174<td> 10175 <p> 10176 Zone transfer requests failed. 10177 </p> 10178 </td> 10179</tr> 10180</tbody> 10181</table></div> 10182</div> 10183<div class="sect3" lang="en"> 10184<div class="titlepage"><div><div><h4 class="title"> 10185<a name="id2601308"></a>Resolver Statistics Counters</h4></div></div></div> 10186<div class="informaltable"><table border="1"> 10187<colgroup> 10188<col> 10189<col> 10190<col> 10191</colgroup> 10192<tbody> 10193<tr> 10194<td> 10195 <p> 10196 <span class="emphasis"><em>Symbol</em></span> 10197 </p> 10198 </td> 10199<td> 10200 <p> 10201 <span class="emphasis"><em>BIND8 Symbol</em></span> 10202 </p> 10203 </td> 10204<td> 10205 <p> 10206 <span class="emphasis"><em>Description</em></span> 10207 </p> 10208 </td> 10209</tr> 10210<tr> 10211<td> 10212 <p><span><strong class="command">Queryv4</strong></span></p> 10213 </td> 10214<td> 10215 <p><span><strong class="command">SFwdQ</strong></span></p> 10216 </td> 10217<td> 10218 <p> 10219 IPv4 queries sent. 10220 </p> 10221 </td> 10222</tr> 10223<tr> 10224<td> 10225 <p><span><strong class="command">Queryv6</strong></span></p> 10226 </td> 10227<td> 10228 <p><span><strong class="command">SFwdQ</strong></span></p> 10229 </td> 10230<td> 10231 <p> 10232 IPv6 queries sent. 10233 </p> 10234 </td> 10235</tr> 10236<tr> 10237<td> 10238 <p><span><strong class="command">Responsev4</strong></span></p> 10239 </td> 10240<td> 10241 <p><span><strong class="command">RR</strong></span></p> 10242 </td> 10243<td> 10244 <p> 10245 IPv4 responses received. 10246 </p> 10247 </td> 10248</tr> 10249<tr> 10250<td> 10251 <p><span><strong class="command">Responsev6</strong></span></p> 10252 </td> 10253<td> 10254 <p><span><strong class="command">RR</strong></span></p> 10255 </td> 10256<td> 10257 <p> 10258 IPv6 responses received. 10259 </p> 10260 </td> 10261</tr> 10262<tr> 10263<td> 10264 <p><span><strong class="command">NXDOMAIN</strong></span></p> 10265 </td> 10266<td> 10267 <p><span><strong class="command">RNXD</strong></span></p> 10268 </td> 10269<td> 10270 <p> 10271 NXDOMAIN received. 10272 </p> 10273 </td> 10274</tr> 10275<tr> 10276<td> 10277 <p><span><strong class="command">SERVFAIL</strong></span></p> 10278 </td> 10279<td> 10280 <p><span><strong class="command">RFail</strong></span></p> 10281 </td> 10282<td> 10283 <p> 10284 SERVFAIL received. 10285 </p> 10286 </td> 10287</tr> 10288<tr> 10289<td> 10290 <p><span><strong class="command">FORMERR</strong></span></p> 10291 </td> 10292<td> 10293 <p><span><strong class="command">RFErr</strong></span></p> 10294 </td> 10295<td> 10296 <p> 10297 FORMERR received. 10298 </p> 10299 </td> 10300</tr> 10301<tr> 10302<td> 10303 <p><span><strong class="command">OtherError</strong></span></p> 10304 </td> 10305<td> 10306 <p><span><strong class="command">RErr</strong></span></p> 10307 </td> 10308<td> 10309 <p> 10310 Other errors received. 10311 </p> 10312 </td> 10313</tr> 10314<tr> 10315<td> 10316 <p><span><strong class="command">EDNS0Fail</strong></span></p> 10317 </td> 10318<td> 10319 <p><span><strong class="command"></strong></span></p> 10320 </td> 10321<td> 10322 <p> 10323 EDNS(0) query failures. 10324 </p> 10325 </td> 10326</tr> 10327<tr> 10328<td> 10329 <p><span><strong class="command">Mismatch</strong></span></p> 10330 </td> 10331<td> 10332 <p><span><strong class="command">RDupR</strong></span></p> 10333 </td> 10334<td> 10335 <p> 10336 Mismatch responses received. 10337 The DNS ID, response's source address, 10338 and/or the response's source port does not 10339 match what was expected. 10340 (The port must be 53 or as defined by 10341 the <span><strong class="command">port</strong></span> option.) 10342 This may be an indication of a cache 10343 poisoning attempt. 10344 </p> 10345 </td> 10346</tr> 10347<tr> 10348<td> 10349 <p><span><strong class="command">Truncated</strong></span></p> 10350 </td> 10351<td> 10352 <p><span><strong class="command"></strong></span></p> 10353 </td> 10354<td> 10355 <p> 10356 Truncated responses received. 10357 </p> 10358 </td> 10359</tr> 10360<tr> 10361<td> 10362 <p><span><strong class="command">Lame</strong></span></p> 10363 </td> 10364<td> 10365 <p><span><strong class="command">RLame</strong></span></p> 10366 </td> 10367<td> 10368 <p> 10369 Lame delegations received. 10370 </p> 10371 </td> 10372</tr> 10373<tr> 10374<td> 10375 <p><span><strong class="command">Retry</strong></span></p> 10376 </td> 10377<td> 10378 <p><span><strong class="command">SDupQ</strong></span></p> 10379 </td> 10380<td> 10381 <p> 10382 Query retries performed. 10383 </p> 10384 </td> 10385</tr> 10386<tr> 10387<td> 10388 <p><span><strong class="command">QueryAbort</strong></span></p> 10389 </td> 10390<td> 10391 <p><span><strong class="command"></strong></span></p> 10392 </td> 10393<td> 10394 <p> 10395 Queries aborted due to quota control. 10396 </p> 10397 </td> 10398</tr> 10399<tr> 10400<td> 10401 <p><span><strong class="command">QuerySockFail</strong></span></p> 10402 </td> 10403<td> 10404 <p><span><strong class="command"></strong></span></p> 10405 </td> 10406<td> 10407 <p> 10408 Failures in opening query sockets. 10409 One common reason for such failures is a 10410 failure of opening a new socket due to a 10411 limitation on file descriptors. 10412 </p> 10413 </td> 10414</tr> 10415<tr> 10416<td> 10417 <p><span><strong class="command">QueryTimeout</strong></span></p> 10418 </td> 10419<td> 10420 <p><span><strong class="command"></strong></span></p> 10421 </td> 10422<td> 10423 <p> 10424 Query timeouts. 10425 </p> 10426 </td> 10427</tr> 10428<tr> 10429<td> 10430 <p><span><strong class="command">GlueFetchv4</strong></span></p> 10431 </td> 10432<td> 10433 <p><span><strong class="command">SSysQ</strong></span></p> 10434 </td> 10435<td> 10436 <p> 10437 IPv4 NS address fetches invoked. 10438 </p> 10439 </td> 10440</tr> 10441<tr> 10442<td> 10443 <p><span><strong class="command">GlueFetchv6</strong></span></p> 10444 </td> 10445<td> 10446 <p><span><strong class="command">SSysQ</strong></span></p> 10447 </td> 10448<td> 10449 <p> 10450 IPv6 NS address fetches invoked. 10451 </p> 10452 </td> 10453</tr> 10454<tr> 10455<td> 10456 <p><span><strong class="command">GlueFetchv4Fail</strong></span></p> 10457 </td> 10458<td> 10459 <p><span><strong class="command"></strong></span></p> 10460 </td> 10461<td> 10462 <p> 10463 IPv4 NS address fetch failed. 10464 </p> 10465 </td> 10466</tr> 10467<tr> 10468<td> 10469 <p><span><strong class="command">GlueFetchv6Fail</strong></span></p> 10470 </td> 10471<td> 10472 <p><span><strong class="command"></strong></span></p> 10473 </td> 10474<td> 10475 <p> 10476 IPv6 NS address fetch failed. 10477 </p> 10478 </td> 10479</tr> 10480<tr> 10481<td> 10482 <p><span><strong class="command">ValAttempt</strong></span></p> 10483 </td> 10484<td> 10485 <p><span><strong class="command"></strong></span></p> 10486 </td> 10487<td> 10488 <p> 10489 DNSSEC validation attempted. 10490 </p> 10491 </td> 10492</tr> 10493<tr> 10494<td> 10495 <p><span><strong class="command">ValOk</strong></span></p> 10496 </td> 10497<td> 10498 <p><span><strong class="command"></strong></span></p> 10499 </td> 10500<td> 10501 <p> 10502 DNSSEC validation succeeded. 10503 </p> 10504 </td> 10505</tr> 10506<tr> 10507<td> 10508 <p><span><strong class="command">ValNegOk</strong></span></p> 10509 </td> 10510<td> 10511 <p><span><strong class="command"></strong></span></p> 10512 </td> 10513<td> 10514 <p> 10515 DNSSEC validation on negative information succeeded. 10516 </p> 10517 </td> 10518</tr> 10519<tr> 10520<td> 10521 <p><span><strong class="command">ValFail</strong></span></p> 10522 </td> 10523<td> 10524 <p><span><strong class="command"></strong></span></p> 10525 </td> 10526<td> 10527 <p> 10528 DNSSEC validation failed. 10529 </p> 10530 </td> 10531</tr> 10532<tr> 10533<td> 10534 <p><span><strong class="command">QryRTTnn</strong></span></p> 10535 </td> 10536<td> 10537 <p><span><strong class="command"></strong></span></p> 10538 </td> 10539<td> 10540 <p> 10541 Frequency table on round trip times (RTTs) of 10542 queries. 10543 Each <span><strong class="command">nn</strong></span> specifies the corresponding 10544 frequency. 10545 In the sequence of 10546 <span><strong class="command">nn_1</strong></span>, 10547 <span><strong class="command">nn_2</strong></span>, 10548 ..., 10549 <span><strong class="command">nn_m</strong></span>, 10550 the value of <span><strong class="command">nn_i</strong></span> is the 10551 number of queries whose RTTs are between 10552 <span><strong class="command">nn_(i-1)</strong></span> (inclusive) and 10553 <span><strong class="command">nn_i</strong></span> (exclusive) milliseconds. 10554 For the sake of convenience we define 10555 <span><strong class="command">nn_0</strong></span> to be 0. 10556 The last entry should be represented as 10557 <span><strong class="command">nn_m+</strong></span>, which means the 10558 number of queries whose RTTs are equal to or over 10559 <span><strong class="command">nn_m</strong></span> milliseconds. 10560 </p> 10561 </td> 10562</tr> 10563</tbody> 10564</table></div> 10565</div> 10566<div class="sect3" lang="en"> 10567<div class="titlepage"><div><div><h4 class="title"> 10568<a name="id2602398"></a>Socket I/O Statistics Counters</h4></div></div></div> 10569<p> 10570 Socket I/O statistics counters are defined per socket 10571 types, which are 10572 <span><strong class="command">UDP4</strong></span> (UDP/IPv4), 10573 <span><strong class="command">UDP6</strong></span> (UDP/IPv6), 10574 <span><strong class="command">TCP4</strong></span> (TCP/IPv4), 10575 <span><strong class="command">TCP6</strong></span> (TCP/IPv6), 10576 <span><strong class="command">Unix</strong></span> (Unix Domain), and 10577 <span><strong class="command">FDwatch</strong></span> (sockets opened outside the 10578 socket module). 10579 In the following table <span><strong class="command"><TYPE></strong></span> 10580 represents a socket type. 10581 Not all counters are available for all socket types; 10582 exceptions are noted in the description field. 10583 </p> 10584<div class="informaltable"><table border="1"> 10585<colgroup> 10586<col> 10587<col> 10588</colgroup> 10589<tbody> 10590<tr> 10591<td> 10592 <p> 10593 <span class="emphasis"><em>Symbol</em></span> 10594 </p> 10595 </td> 10596<td> 10597 <p> 10598 <span class="emphasis"><em>Description</em></span> 10599 </p> 10600 </td> 10601</tr> 10602<tr> 10603<td> 10604 <p><span><strong class="command"><TYPE>Open</strong></span></p> 10605 </td> 10606<td> 10607 <p> 10608 Sockets opened successfully. 10609 This counter is not applicable to the 10610 <span><strong class="command">FDwatch</strong></span> type. 10611 </p> 10612 </td> 10613</tr> 10614<tr> 10615<td> 10616 <p><span><strong class="command"><TYPE>OpenFail</strong></span></p> 10617 </td> 10618<td> 10619 <p> 10620 Failures of opening sockets. 10621 This counter is not applicable to the 10622 <span><strong class="command">FDwatch</strong></span> type. 10623 </p> 10624 </td> 10625</tr> 10626<tr> 10627<td> 10628 <p><span><strong class="command"><TYPE>Close</strong></span></p> 10629 </td> 10630<td> 10631 <p> 10632 Sockets closed. 10633 </p> 10634 </td> 10635</tr> 10636<tr> 10637<td> 10638 <p><span><strong class="command"><TYPE>BindFail</strong></span></p> 10639 </td> 10640<td> 10641 <p> 10642 Failures of binding sockets. 10643 </p> 10644 </td> 10645</tr> 10646<tr> 10647<td> 10648 <p><span><strong class="command"><TYPE>ConnFail</strong></span></p> 10649 </td> 10650<td> 10651 <p> 10652 Failures of connecting sockets. 10653 </p> 10654 </td> 10655</tr> 10656<tr> 10657<td> 10658 <p><span><strong class="command"><TYPE>Conn</strong></span></p> 10659 </td> 10660<td> 10661 <p> 10662 Connections established successfully. 10663 </p> 10664 </td> 10665</tr> 10666<tr> 10667<td> 10668 <p><span><strong class="command"><TYPE>AcceptFail</strong></span></p> 10669 </td> 10670<td> 10671 <p> 10672 Failures of accepting incoming connection requests. 10673 This counter is not applicable to the 10674 <span><strong class="command">UDP</strong></span> and 10675 <span><strong class="command">FDwatch</strong></span> types. 10676 </p> 10677 </td> 10678</tr> 10679<tr> 10680<td> 10681 <p><span><strong class="command"><TYPE>Accept</strong></span></p> 10682 </td> 10683<td> 10684 <p> 10685 Incoming connections successfully accepted. 10686 This counter is not applicable to the 10687 <span><strong class="command">UDP</strong></span> and 10688 <span><strong class="command">FDwatch</strong></span> types. 10689 </p> 10690 </td> 10691</tr> 10692<tr> 10693<td> 10694 <p><span><strong class="command"><TYPE>SendErr</strong></span></p> 10695 </td> 10696<td> 10697 <p> 10698 Errors in socket send operations. 10699 This counter corresponds 10700 to <span><strong class="command">SErr</strong></span> counter of 10701 <span><strong class="command">BIND</strong></span> 8. 10702 </p> 10703 </td> 10704</tr> 10705<tr> 10706<td> 10707 <p><span><strong class="command"><TYPE>RecvErr</strong></span></p> 10708 </td> 10709<td> 10710 <p> 10711 Errors in socket receive operations. 10712 This includes errors of send operations on a 10713 connected UDP socket notified by an ICMP error 10714 message. 10715 </p> 10716 </td> 10717</tr> 10718</tbody> 10719</table></div> 10720</div> 10721<div class="sect3" lang="en"> 10722<div class="titlepage"><div><div><h4 class="title"> 10723<a name="id2602840"></a>Compatibility with <span class="emphasis"><em>BIND</em></span> 8 Counters</h4></div></div></div> 10724<p> 10725 Most statistics counters that were available 10726 in <span><strong class="command">BIND</strong></span> 8 are also supported in 10727 <span><strong class="command">BIND</strong></span> 9 as shown in the above tables. 10728 Here are notes about other counters that do not appear 10729 in these tables. 10730 </p> 10731<div class="variablelist"><dl> 10732<dt><span class="term"><span><strong class="command">RFwdR,SFwdR</strong></span></span></dt> 10733<dd><p> 10734 These counters are not supported 10735 because <span><strong class="command">BIND</strong></span> 9 does not adopt 10736 the notion of <span class="emphasis"><em>forwarding</em></span> 10737 as <span><strong class="command">BIND</strong></span> 8 did. 10738 </p></dd> 10739<dt><span class="term"><span><strong class="command">RAXFR</strong></span></span></dt> 10740<dd><p> 10741 This counter is accessible in the Incoming Queries section. 10742 </p></dd> 10743<dt><span class="term"><span><strong class="command">RIQ</strong></span></span></dt> 10744<dd><p> 10745 This counter is accessible in the Incoming Requests section. 10746 </p></dd> 10747<dt><span class="term"><span><strong class="command">ROpts</strong></span></span></dt> 10748<dd><p> 10749 This counter is not supported 10750 because <span><strong class="command">BIND</strong></span> 9 does not care 10751 about IP options in the first place. 10752 </p></dd> 10753</dl></div> 10754</div> 10755</div> 10756</div> 10757</div> 10758<div class="navfooter"> 10759<hr> 10760<table width="100%" summary="Navigation footer"> 10761<tr> 10762<td width="40%" align="left"> 10763<a accesskey="p" href="Bv9ARM.ch05.html">Prev</a>�</td> 10764<td width="20%" align="center">�</td> 10765<td width="40%" align="right">�<a accesskey="n" href="Bv9ARM.ch07.html">Next</a> 10766</td> 10767</tr> 10768<tr> 10769<td width="40%" align="left" valign="top">Chapter�5.�The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver�</td> 10770<td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td> 10771<td width="40%" align="right" valign="top">�Chapter�7.�<acronym class="acronym">BIND</acronym> 9 Security Considerations</td> 10772</tr> 10773</table> 10774</div> 10775</body> 10776</html> 10777