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43<a name="man.named"></a><div class="titlepage"></div>
44<div class="refnamediv">
45<h2>Name</h2>
46<p><span class="application">named</span> &#8212; Internet domain name server</p>
47</div>
48<div class="refsynopsisdiv">
49<h2>Synopsis</h2>
50<div class="cmdsynopsis"><p><code class="command">named</code>  [<code class="option">-4</code>] [<code class="option">-6</code>] [<code class="option">-c <em class="replaceable"><code>config-file</code></em></code>] [<code class="option">-d <em class="replaceable"><code>debug-level</code></em></code>] [<code class="option">-f</code>] [<code class="option">-g</code>] [<code class="option">-m <em class="replaceable"><code>flag</code></em></code>] [<code class="option">-n <em class="replaceable"><code>#cpus</code></em></code>] [<code class="option">-p <em class="replaceable"><code>port</code></em></code>] [<code class="option">-s</code>] [<code class="option">-S <em class="replaceable"><code>#max-socks</code></em></code>] [<code class="option">-t <em class="replaceable"><code>directory</code></em></code>] [<code class="option">-u <em class="replaceable"><code>user</code></em></code>] [<code class="option">-v</code>] [<code class="option">-V</code>] [<code class="option">-x <em class="replaceable"><code>cache-file</code></em></code>]</p></div>
51</div>
52<div class="refsect1" lang="en">
53<a name="id2610525"></a><h2>DESCRIPTION</h2>
54<p><span><strong class="command">named</strong></span>
55      is a Domain Name System (DNS) server,
56      part of the BIND 9 distribution from ISC.  For more
57      information on the DNS, see RFCs 1033, 1034, and 1035.
58    </p>
59<p>
60      When invoked without arguments, <span><strong class="command">named</strong></span>
61      will
62      read the default configuration file
63      <code class="filename">/etc/named.conf</code>, read any initial
64      data, and listen for queries.
65    </p>
66</div>
67<div class="refsect1" lang="en">
68<a name="id2610556"></a><h2>OPTIONS</h2>
69<div class="variablelist"><dl>
70<dt><span class="term">-4</span></dt>
71<dd><p>
72            Use IPv4 only even if the host machine is capable of IPv6.
73            <code class="option">-4</code> and <code class="option">-6</code> are mutually
74            exclusive.
75          </p></dd>
76<dt><span class="term">-6</span></dt>
77<dd><p>
78            Use IPv6 only even if the host machine is capable of IPv4.
79            <code class="option">-4</code> and <code class="option">-6</code> are mutually
80            exclusive.
81          </p></dd>
82<dt><span class="term">-c <em class="replaceable"><code>config-file</code></em></span></dt>
83<dd><p>
84            Use <em class="replaceable"><code>config-file</code></em> as the
85            configuration file instead of the default,
86            <code class="filename">/etc/named.conf</code>.  To
87            ensure that reloading the configuration file continues
88            to work after the server has changed its working
89            directory due to to a possible
90            <code class="option">directory</code> option in the configuration
91            file, <em class="replaceable"><code>config-file</code></em> should be
92            an absolute pathname.
93          </p></dd>
94<dt><span class="term">-d <em class="replaceable"><code>debug-level</code></em></span></dt>
95<dd><p>
96            Set the daemon's debug level to <em class="replaceable"><code>debug-level</code></em>.
97            Debugging traces from <span><strong class="command">named</strong></span> become
98            more verbose as the debug level increases.
99          </p></dd>
100<dt><span class="term">-f</span></dt>
101<dd><p>
102            Run the server in the foreground (i.e. do not daemonize).
103          </p></dd>
104<dt><span class="term">-g</span></dt>
105<dd><p>
106            Run the server in the foreground and force all logging
107            to <code class="filename">stderr</code>.
108          </p></dd>
109<dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
110<dd><p>
111	    Turn on memory usage debugging flags.  Possible flags are
112	    <em class="replaceable"><code>usage</code></em>,
113	    <em class="replaceable"><code>trace</code></em>,
114	    <em class="replaceable"><code>record</code></em>,
115	    <em class="replaceable"><code>size</code></em>, and
116	    <em class="replaceable"><code>mctx</code></em>.
117	    These correspond to the ISC_MEM_DEBUGXXXX flags described in
118	    <code class="filename">&lt;isc/mem.h&gt;</code>.
119          </p></dd>
120<dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt>
121<dd><p>
122            Create <em class="replaceable"><code>#cpus</code></em> worker threads
123            to take advantage of multiple CPUs.  If not specified,
124            <span><strong class="command">named</strong></span> will try to determine the
125            number of CPUs present and create one thread per CPU.
126            If it is unable to determine the number of CPUs, a
127            single worker thread will be created.
128          </p></dd>
129<dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt>
130<dd><p>
131            Listen for queries on port <em class="replaceable"><code>port</code></em>.  If not
132            specified, the default is port 53.
133          </p></dd>
134<dt><span class="term">-s</span></dt>
135<dd>
136<p>
137            Write memory usage statistics to <code class="filename">stdout</code> on exit.
138          </p>
139<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
140<h3 class="title">Note</h3>
141<p>
142              This option is mainly of interest to BIND 9 developers
143              and may be removed or changed in a future release.
144            </p>
145</div>
146</dd>
147<dt><span class="term">-S <em class="replaceable"><code>#max-socks</code></em></span></dt>
148<dd>
149<p>
150	    Allow <span><strong class="command">named</strong></span> to use up to
151	    <em class="replaceable"><code>#max-socks</code></em> sockets.
152	  </p>
153<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
154<h3 class="title">Warning</h3>
155<p>
156              This option should be unnecessary for the vast majority
157              of users.
158	      The use of this option could even be harmful because the
159              specified value may exceed the limitation of the
160              underlying system API.
161	      It is therefore set only when the default configuration
162              causes exhaustion of file descriptors and the
163              operational environment is known to support the
164              specified number of sockets.
165	      Note also that the actual maximum number is normally a little
166              fewer than the specified value because
167	      <span><strong class="command">named</strong></span> reserves some file descriptors
168	      for its internal use.
169            </p>
170</div>
171</dd>
172<dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt>
173<dd>
174<p>Chroot
175	    to <em class="replaceable"><code>directory</code></em> after
176            processing the command line arguments, but before
177            reading the configuration file.
178          </p>
179<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
180<h3 class="title">Warning</h3>
181<p>
182              This option should be used in conjunction with the
183              <code class="option">-u</code> option, as chrooting a process
184              running as root doesn't enhance security on most
185              systems; the way <code class="function">chroot(2)</code> is
186              defined allows a process with root privileges to
187              escape a chroot jail.
188            </p>
189</div>
190</dd>
191<dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt>
192<dd>
193<p>Setuid
194	    to <em class="replaceable"><code>user</code></em> after completing
195            privileged operations, such as creating sockets that
196            listen on privileged ports.
197          </p>
198<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
199<h3 class="title">Note</h3>
200<p>
201              On Linux, <span><strong class="command">named</strong></span> uses the kernel's
202              		capability mechanism to drop all root privileges
203              except the ability to <code class="function">bind(2)</code> to
204              a
205              privileged port and set process resource limits.
206              Unfortunately, this means that the <code class="option">-u</code>
207              option only works when <span><strong class="command">named</strong></span> is
208              run
209              on kernel 2.2.18 or later, or kernel 2.3.99-pre3 or
210              later, since previous kernels did not allow privileges
211              to be retained after <code class="function">setuid(2)</code>.
212            </p>
213</div>
214</dd>
215<dt><span class="term">-v</span></dt>
216<dd><p>
217            Report the version number and exit.
218          </p></dd>
219<dt><span class="term">-V</span></dt>
220<dd><p>
221            Report the version number and build options, and exit.
222          </p></dd>
223<dt><span class="term">-x <em class="replaceable"><code>cache-file</code></em></span></dt>
224<dd>
225<p>
226            Load data from <em class="replaceable"><code>cache-file</code></em> into the
227            cache of the default view.
228          </p>
229<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
230<h3 class="title">Warning</h3>
231<p>
232              This option must not be used.  It is only of interest
233              to BIND 9 developers and may be removed or changed in a
234              future release.
235            </p>
236</div>
237</dd>
238</dl></div>
239</div>
240<div class="refsect1" lang="en">
241<a name="id2652594"></a><h2>SIGNALS</h2>
242<p>
243      In routine operation, signals should not be used to control
244      the nameserver; <span><strong class="command">rndc</strong></span> should be used
245      instead.
246    </p>
247<div class="variablelist"><dl>
248<dt><span class="term">SIGHUP</span></dt>
249<dd><p>
250            Force a reload of the server.
251          </p></dd>
252<dt><span class="term">SIGINT, SIGTERM</span></dt>
253<dd><p>
254            Shut down the server.
255          </p></dd>
256</dl></div>
257<p>
258      The result of sending any other signals to the server is undefined.
259    </p>
260</div>
261<div class="refsect1" lang="en">
262<a name="id2652644"></a><h2>CONFIGURATION</h2>
263<p>
264      The <span><strong class="command">named</strong></span> configuration file is too complex
265      to describe in detail here.  A complete description is provided
266      in the
267      <em class="citetitle">BIND 9 Administrator Reference Manual</em>.
268    </p>
269<p>
270      <span><strong class="command">named</strong></span> inherits the <code class="function">umask</code>
271      (file creation mode mask) from the parent process. If files
272      created by <span><strong class="command">named</strong></span>, such as journal files,
273      need to have custom permissions, the <code class="function">umask</code>
274      should be set explicitly in the script used to start the
275      <span><strong class="command">named</strong></span> process.
276    </p>
277</div>
278<div class="refsect1" lang="en">
279<a name="id2652693"></a><h2>FILES</h2>
280<div class="variablelist"><dl>
281<dt><span class="term"><code class="filename">/etc/named.conf</code></span></dt>
282<dd><p>
283            The default configuration file.
284          </p></dd>
285<dt><span class="term"><code class="filename">/var/run/named/named.pid</code></span></dt>
286<dd><p>
287            The default process-id file.
288          </p></dd>
289</dl></div>
290</div>
291<div class="refsect1" lang="en">
292<a name="id2659836"></a><h2>SEE ALSO</h2>
293<p><em class="citetitle">RFC 1033</em>,
294      <em class="citetitle">RFC 1034</em>,
295      <em class="citetitle">RFC 1035</em>,
296      <span class="citerefentry"><span class="refentrytitle">named-checkconf</span>(8)</span>,
297      <span class="citerefentry"><span class="refentrytitle">named-checkzone</span>(8)</span>,
298      <span class="citerefentry"><span class="refentrytitle">rndc</span>(8)</span>,
299      <span class="citerefentry"><span class="refentrytitle">lwresd</span>(8)</span>,
300      <span class="citerefentry"><span class="refentrytitle">named.conf</span>(5)</span>,
301      <em class="citetitle">BIND 9 Administrator Reference Manual</em>.
302    </p>
303</div>
304<div class="refsect1" lang="en">
305<a name="id2659907"></a><h2>AUTHOR</h2>
306<p><span class="corpauthor">Internet Systems Consortium</span>
307    </p>
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