1170222Sdougb<!-- 2254402Serwin - Copyright (C) 2004-2013 Internet Systems Consortium, Inc. ("ISC") 3170222Sdougb - Copyright (C) 2000-2003 Internet Software Consortium. 4170222Sdougb - 5204619Sdougb - Permission to use, copy, modify, and/or distribute this software for any 6170222Sdougb - purpose with or without fee is hereby granted, provided that the above 7170222Sdougb - copyright notice and this permission notice appear in all copies. 8170222Sdougb - 9170222Sdougb - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 10170222Sdougb - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 11170222Sdougb - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 12170222Sdougb - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 13170222Sdougb - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 14170222Sdougb - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 15170222Sdougb - PERFORMANCE OF THIS SOFTWARE. 16170222Sdougb--> 17234010Sdougb<!-- $Id$ --> 18170222Sdougb<html> 19170222Sdougb<head> 20170222Sdougb<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 21170222Sdougb<title>host</title> 22170222Sdougb<meta name="generator" content="DocBook XSL Stylesheets V1.71.1"> 23170222Sdougb<link rel="start" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual"> 24170222Sdougb<link rel="up" href="Bv9ARM.ch10.html" title="Manual pages"> 25170222Sdougb<link rel="prev" href="man.dig.html" title="dig"> 26254897Serwin<link rel="next" href="man.dnssec-checkds.html" title="dnssec-checkds"> 27170222Sdougb</head> 28170222Sdougb<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 29170222Sdougb<div class="navheader"> 30170222Sdougb<table width="100%" summary="Navigation header"> 31170222Sdougb<tr><th colspan="3" align="center">host</th></tr> 32170222Sdougb<tr> 33170222Sdougb<td width="20%" align="left"> 34170222Sdougb<a accesskey="p" href="man.dig.html">Prev</a>�</td> 35170222Sdougb<th width="60%" align="center">Manual pages</th> 36254897Serwin<td width="20%" align="right">�<a accesskey="n" href="man.dnssec-checkds.html">Next</a> 37170222Sdougb</td> 38170222Sdougb</tr> 39170222Sdougb</table> 40170222Sdougb<hr> 41170222Sdougb</div> 42170222Sdougb<div class="refentry" lang="en"> 43170222Sdougb<a name="man.host"></a><div class="titlepage"></div> 44170222Sdougb<div class="refnamediv"> 45170222Sdougb<h2>Name</h2> 46170222Sdougb<p>host — DNS lookup utility</p> 47170222Sdougb</div> 48170222Sdougb<div class="refsynopsisdiv"> 49170222Sdougb<h2>Synopsis</h2> 50170222Sdougb<div class="cmdsynopsis"><p><code class="command">host</code> [<code class="option">-aCdlnrsTwv</code>] [<code class="option">-c <em class="replaceable"><code>class</code></em></code>] [<code class="option">-N <em class="replaceable"><code>ndots</code></em></code>] [<code class="option">-R <em class="replaceable"><code>number</code></em></code>] [<code class="option">-t <em class="replaceable"><code>type</code></em></code>] [<code class="option">-W <em class="replaceable"><code>wait</code></em></code>] [<code class="option">-m <em class="replaceable"><code>flag</code></em></code>] [<code class="option">-4</code>] [<code class="option">-6</code>] {name} [server]</p></div> 51170222Sdougb</div> 52170222Sdougb<div class="refsect1" lang="en"> 53262706Serwin<a name="id2612021"></a><h2>DESCRIPTION</h2> 54170222Sdougb<p><span><strong class="command">host</strong></span> 55170222Sdougb is a simple utility for performing DNS lookups. 56170222Sdougb It is normally used to convert names to IP addresses and vice versa. 57170222Sdougb When no arguments or options are given, 58170222Sdougb <span><strong class="command">host</strong></span> 59170222Sdougb prints a short summary of its command line arguments and options. 60170222Sdougb </p> 61170222Sdougb<p><em class="parameter"><code>name</code></em> is the domain name that is to be 62170222Sdougb looked 63170222Sdougb up. It can also be a dotted-decimal IPv4 address or a colon-delimited 64170222Sdougb IPv6 address, in which case <span><strong class="command">host</strong></span> will by 65170222Sdougb default 66170222Sdougb perform a reverse lookup for that address. 67170222Sdougb <em class="parameter"><code>server</code></em> is an optional argument which 68170222Sdougb is either 69170222Sdougb the name or IP address of the name server that <span><strong class="command">host</strong></span> 70170222Sdougb should query instead of the server or servers listed in 71170222Sdougb <code class="filename">/etc/resolv.conf</code>. 72170222Sdougb </p> 73170222Sdougb<p> 74170222Sdougb The <code class="option">-a</code> (all) option is equivalent to setting the 75170222Sdougb <code class="option">-v</code> option and asking <span><strong class="command">host</strong></span> to make 76170222Sdougb a query of type ANY. 77170222Sdougb </p> 78170222Sdougb<p> 79170222Sdougb When the <code class="option">-C</code> option is used, <span><strong class="command">host</strong></span> 80170222Sdougb will attempt to display the SOA records for zone 81170222Sdougb <em class="parameter"><code>name</code></em> from all the listed 82170222Sdougb authoritative name 83170222Sdougb servers for that zone. The list of name servers is defined by the NS 84170222Sdougb records that are found for the zone. 85170222Sdougb </p> 86170222Sdougb<p> 87170222Sdougb The <code class="option">-c</code> option instructs to make a DNS query of class 88170222Sdougb <em class="parameter"><code>class</code></em>. This can be used to lookup 89170222Sdougb Hesiod or 90170222Sdougb Chaosnet class resource records. The default class is IN (Internet). 91170222Sdougb </p> 92170222Sdougb<p> 93170222Sdougb Verbose output is generated by <span><strong class="command">host</strong></span> when 94170222Sdougb the 95170222Sdougb <code class="option">-d</code> or <code class="option">-v</code> option is used. The two 96170222Sdougb options are equivalent. They have been provided for backwards 97170222Sdougb compatibility. In previous versions, the <code class="option">-d</code> option 98170222Sdougb switched on debugging traces and <code class="option">-v</code> enabled verbose 99170222Sdougb output. 100170222Sdougb </p> 101170222Sdougb<p> 102170222Sdougb List mode is selected by the <code class="option">-l</code> option. This makes 103170222Sdougb <span><strong class="command">host</strong></span> perform a zone transfer for zone 104170222Sdougb <em class="parameter"><code>name</code></em>. Transfer the zone printing out 105170222Sdougb the NS, PTR 106170222Sdougb and address records (A/AAAA). If combined with <code class="option">-a</code> 107170222Sdougb all records will be printed. 108170222Sdougb </p> 109170222Sdougb<p> 110170222Sdougb The <code class="option">-i</code> 111170222Sdougb option specifies that reverse lookups of IPv6 addresses should 112170222Sdougb use the IP6.INT domain as defined in RFC1886. 113170222Sdougb The default is to use IP6.ARPA. 114170222Sdougb </p> 115170222Sdougb<p> 116170222Sdougb The <code class="option">-N</code> option sets the number of dots that have to be 117170222Sdougb in <em class="parameter"><code>name</code></em> for it to be considered 118170222Sdougb absolute. The 119170222Sdougb default value is that defined using the ndots statement in 120170222Sdougb <code class="filename">/etc/resolv.conf</code>, or 1 if no ndots 121170222Sdougb statement is 122170222Sdougb present. Names with fewer dots are interpreted as relative names and 123170222Sdougb will be searched for in the domains listed in the <span class="type">search</span> 124170222Sdougb or <span class="type">domain</span> directive in 125170222Sdougb <code class="filename">/etc/resolv.conf</code>. 126170222Sdougb </p> 127170222Sdougb<p> 128170222Sdougb The number of UDP retries for a lookup can be changed with the 129170222Sdougb <code class="option">-R</code> option. <em class="parameter"><code>number</code></em> 130170222Sdougb indicates 131170222Sdougb how many times <span><strong class="command">host</strong></span> will repeat a query 132170222Sdougb that does 133170222Sdougb not get answered. The default number of retries is 1. If 134170222Sdougb <em class="parameter"><code>number</code></em> is negative or zero, the 135170222Sdougb number of 136170222Sdougb retries will default to 1. 137170222Sdougb </p> 138170222Sdougb<p> 139170222Sdougb Non-recursive queries can be made via the <code class="option">-r</code> option. 140170222Sdougb Setting this option clears the <span class="type">RD</span> — recursion 141170222Sdougb desired — bit in the query which <span><strong class="command">host</strong></span> makes. 142170222Sdougb This should mean that the name server receiving the query will not 143170222Sdougb attempt to resolve <em class="parameter"><code>name</code></em>. The 144170222Sdougb <code class="option">-r</code> option enables <span><strong class="command">host</strong></span> 145170222Sdougb to mimic 146174187Sdougb the behavior of a name server by making non-recursive queries and 147170222Sdougb expecting to receive answers to those queries that are usually 148170222Sdougb referrals to other name servers. 149170222Sdougb </p> 150170222Sdougb<p> 151193149Sdougb By default, <span><strong class="command">host</strong></span> uses UDP when making 152170222Sdougb queries. The 153170222Sdougb <code class="option">-T</code> option makes it use a TCP connection when querying 154170222Sdougb the name server. TCP will be automatically selected for queries that 155170222Sdougb require it, such as zone transfer (AXFR) requests. 156170222Sdougb </p> 157170222Sdougb<p> 158170222Sdougb The <code class="option">-4</code> option forces <span><strong class="command">host</strong></span> to only 159170222Sdougb use IPv4 query transport. The <code class="option">-6</code> option forces 160170222Sdougb <span><strong class="command">host</strong></span> to only use IPv6 query transport. 161170222Sdougb </p> 162170222Sdougb<p> 163170222Sdougb The <code class="option">-t</code> option is used to select the query type. 164174187Sdougb <em class="parameter"><code>type</code></em> can be any recognized query 165170222Sdougb type: CNAME, 166170222Sdougb NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified, 167170222Sdougb <span><strong class="command">host</strong></span> automatically selects an appropriate 168170222Sdougb query 169193149Sdougb type. By default, it looks for A, AAAA, and MX records, but if the 170170222Sdougb <code class="option">-C</code> option was given, queries will be made for SOA 171170222Sdougb records, and if <em class="parameter"><code>name</code></em> is a 172170222Sdougb dotted-decimal IPv4 173170222Sdougb address or colon-delimited IPv6 address, <span><strong class="command">host</strong></span> will 174170222Sdougb query for PTR records. If a query type of IXFR is chosen the starting 175170222Sdougb serial number can be specified by appending an equal followed by the 176170222Sdougb starting serial number (e.g. -t IXFR=12345678). 177170222Sdougb </p> 178170222Sdougb<p> 179170222Sdougb The time to wait for a reply can be controlled through the 180170222Sdougb <code class="option">-W</code> and <code class="option">-w</code> options. The 181170222Sdougb <code class="option">-W</code> option makes <span><strong class="command">host</strong></span> 182170222Sdougb wait for 183170222Sdougb <em class="parameter"><code>wait</code></em> seconds. If <em class="parameter"><code>wait</code></em> 184170222Sdougb is less than one, the wait interval is set to one second. When the 185170222Sdougb <code class="option">-w</code> option is used, <span><strong class="command">host</strong></span> 186170222Sdougb will 187170222Sdougb effectively wait forever for a reply. The time to wait for a response 188170222Sdougb will be set to the number of seconds given by the hardware's maximum 189170222Sdougb value for an integer quantity. 190170222Sdougb </p> 191170222Sdougb<p> 192170222Sdougb The <code class="option">-s</code> option tells <span><strong class="command">host</strong></span> 193170222Sdougb <span class="emphasis"><em>not</em></span> to send the query to the next nameserver 194170222Sdougb if any server responds with a SERVFAIL response, which is the 195174187Sdougb reverse of normal stub resolver behavior. 196170222Sdougb </p> 197170222Sdougb<p> 198170222Sdougb The <code class="option">-m</code> can be used to set the memory usage debugging 199170222Sdougb flags 200170222Sdougb <em class="parameter"><code>record</code></em>, <em class="parameter"><code>usage</code></em> and 201170222Sdougb <em class="parameter"><code>trace</code></em>. 202170222Sdougb </p> 203170222Sdougb</div> 204170222Sdougb<div class="refsect1" lang="en"> 205262706Serwin<a name="id2612535"></a><h2>IDN SUPPORT</h2> 206170222Sdougb<p> 207170222Sdougb If <span><strong class="command">host</strong></span> has been built with IDN (internationalized 208170222Sdougb domain name) support, it can accept and display non-ASCII domain names. 209170222Sdougb <span><strong class="command">host</strong></span> appropriately converts character encoding of 210170222Sdougb domain name before sending a request to DNS server or displaying a 211170222Sdougb reply from the server. 212170222Sdougb If you'd like to turn off the IDN support for some reason, defines 213170222Sdougb the <code class="envar">IDN_DISABLE</code> environment variable. 214170222Sdougb The IDN support is disabled if the variable is set when 215170222Sdougb <span><strong class="command">host</strong></span> runs. 216170222Sdougb </p> 217170222Sdougb</div> 218170222Sdougb<div class="refsect1" lang="en"> 219262706Serwin<a name="id2612564"></a><h2>FILES</h2> 220170222Sdougb<p><code class="filename">/etc/resolv.conf</code> 221170222Sdougb </p> 222170222Sdougb</div> 223170222Sdougb<div class="refsect1" lang="en"> 224262706Serwin<a name="id2612578"></a><h2>SEE ALSO</h2> 225170222Sdougb<p><span class="citerefentry"><span class="refentrytitle">dig</span>(1)</span>, 226170222Sdougb <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>. 227170222Sdougb </p> 228170222Sdougb</div> 229170222Sdougb</div> 230170222Sdougb<div class="navfooter"> 231170222Sdougb<hr> 232170222Sdougb<table width="100%" summary="Navigation footer"> 233170222Sdougb<tr> 234170222Sdougb<td width="40%" align="left"> 235170222Sdougb<a accesskey="p" href="man.dig.html">Prev</a>�</td> 236170222Sdougb<td width="20%" align="center"><a accesskey="u" href="Bv9ARM.ch10.html">Up</a></td> 237254897Serwin<td width="40%" align="right">�<a accesskey="n" href="man.dnssec-checkds.html">Next</a> 238170222Sdougb</td> 239170222Sdougb</tr> 240170222Sdougb<tr> 241170222Sdougb<td width="40%" align="left" valign="top">dig�</td> 242170222Sdougb<td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td> 243254897Serwin<td width="40%" align="right" valign="top">�<span class="application">dnssec-checkds</span> 244170222Sdougb</td> 245170222Sdougb</tr> 246170222Sdougb</table> 247170222Sdougb</div> 248170222Sdougb</body> 249170222Sdougb</html> 250