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60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein - Copyright (C) 2004-2014 Internet Systems Consortium, Inc. ("ISC")
f0aad5341752aefe5059832f6cf3abc3283c6e16Tinderbox User - Copyright (C) 2000-2003 Internet Software Consortium.
5347c0fcb04eaea19d9f39795646239f487c6207Tinderbox User - Permission to use, copy, modify, and/or distribute this software for any
5347c0fcb04eaea19d9f39795646239f487c6207Tinderbox User - purpose with or without fee is hereby granted, provided that the above
5347c0fcb04eaea19d9f39795646239f487c6207Tinderbox User - copyright notice and this permission notice appear in all copies.
d6fa26d0adaec6c910115be34fe7a5a5f402c14fMark Andrews - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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af40ebed6257e4ac1996144530b3de317cf4da11Tinderbox User<a name="man.host"></a><div class="titlepage"></div>
2b4d1b54f6ca406b8233d9e6fea9593df6dad035Tinderbox User<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>] [<code class="option">-v</code>] [<code class="option">-V</code>] {name} [server]</p></div>
af40ebed6257e4ac1996144530b3de317cf4da11Tinderbox User<p><span><strong class="command">host</strong></span>
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt is a simple utility for performing DNS lookups.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein It is normally used to convert names to IP addresses and vice versa.
af40ebed6257e4ac1996144530b3de317cf4da11Tinderbox User When no arguments or options are given,
af40ebed6257e4ac1996144530b3de317cf4da11Tinderbox User <span><strong class="command">host</strong></span>
af40ebed6257e4ac1996144530b3de317cf4da11Tinderbox User prints a short summary of its command line arguments and options.
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt<p><em class="parameter"><code>name</code></em> is the domain name that is to be
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User up. It can also be a dotted-decimal IPv4 address or a colon-delimited
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User IPv6 address, in which case <span><strong class="command">host</strong></span> will by
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User perform a reverse lookup for that address.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <em class="parameter"><code>server</code></em> is an optional argument which
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User the name or IP address of the name server that <span><strong class="command">host</strong></span>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User should query instead of the server or servers listed in
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <code class="filename">/etc/resolv.conf</code>.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User The <code class="option">-a</code> (all) option is equivalent to setting the
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <code class="option">-v</code> option and asking <span><strong class="command">host</strong></span> to make
6f64d4ab8e68f9b2333bcbfc755396d29a4a9d7cAutomatic Updater a query of type ANY.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User When the <code class="option">-C</code> option is used, <span><strong class="command">host</strong></span>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User will attempt to display the SOA records for zone
bbbf2e27d3a981163dab139497d6b2dc85449db0Tinderbox User <em class="parameter"><code>name</code></em> from all the listed
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt authoritative name
bbbf2e27d3a981163dab139497d6b2dc85449db0Tinderbox User servers for that zone. The list of name servers is defined by the NS
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User records that are found for the zone.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User The <code class="option">-c</code> option instructs to make a DNS query of class
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <em class="parameter"><code>class</code></em>. This can be used to lookup
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User Chaosnet class resource records. The default class is IN (Internet).
44d0f0256fbdce130a18655023c3b06bacacbd61Automatic Updater Verbose output is generated by <span><strong class="command">host</strong></span> when
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <code class="option">-d</code> or <code class="option">-v</code> option is used. The two
bcf15a19ae0efa72a22cdfb50666a3c6ce39eb9fTinderbox User options are equivalent. They have been provided for backwards
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt compatibility. In previous versions, the <code class="option">-d</code> option
bcf15a19ae0efa72a22cdfb50666a3c6ce39eb9fTinderbox User switched on debugging traces and <code class="option">-v</code> enabled verbose
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User output. Verbose output can also be enabled by setting the
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <em class="parameter"><code>debug</code></em> option in
983df82baf1d7d0b668c98cf45928a19f175c6e7Tinderbox User <code class="filename">/etc/resolv.conf</code>.
260e8e04b0dc24cb884c789b5d9eb046457f264eTinderbox User List mode is selected by the <code class="option">-l</code> option. This makes
260e8e04b0dc24cb884c789b5d9eb046457f264eTinderbox User <span><strong class="command">host</strong></span> perform a zone transfer for zone
260e8e04b0dc24cb884c789b5d9eb046457f264eTinderbox User <em class="parameter"><code>name</code></em>. Transfer the zone printing out
af40ebed6257e4ac1996144530b3de317cf4da11Tinderbox User and address records (A/AAAA). If combined with <code class="option">-a</code>
983df82baf1d7d0b668c98cf45928a19f175c6e7Tinderbox User all records will be printed.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein option specifies that reverse lookups of IPv6 addresses should
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein use the IP6.INT domain as defined in RFC1886.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User The default is to use IP6.ARPA.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The <code class="option">-N</code> option sets the number of dots that have to be
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User in <em class="parameter"><code>name</code></em> for it to be considered
71c66a876ecca77923638d3f94cc0783152b2f03Mark Andrews absolute. The
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein default value is that defined using the ndots statement in
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt <code class="filename">/etc/resolv.conf</code>, or 1 if no ndots
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein statement is
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein present. Names with fewer dots are interpreted as relative names and
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein will be searched for in the domains listed in the <span class="type">search</span>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User or <span class="type">domain</span> directive in
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <code class="filename">/etc/resolv.conf</code>.
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt The number of UDP retries for a lookup can be changed with the
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt <code class="option">-R</code> option. <em class="parameter"><code>number</code></em>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein how many times <span><strong class="command">host</strong></span> will repeat a query
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User not get answered. If
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <em class="parameter"><code>number</code></em> is negative or zero, the
dec590a3deb8e87380a8bd3a77d535dba3729bf6Tinderbox User retries will default to 1. The default value is 1, or
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt the value of the <em class="parameter"><code>attempts</code></em> option in
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt <code class="filename">/etc/resolv.conf</code>, if set.
5a4557e8de2951a2796676b5ec4b6a90caa5be14Mark Andrews Non-recursive queries can be made via the <code class="option">-r</code> option.
dec590a3deb8e87380a8bd3a77d535dba3729bf6Tinderbox User Setting this option clears the <span class="type">RD</span> — recursion
dec590a3deb8e87380a8bd3a77d535dba3729bf6Tinderbox User desired — bit in the query which <span><strong class="command">host</strong></span> makes.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User This should mean that the name server receiving the query will not
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User attempt to resolve <em class="parameter"><code>name</code></em>. The
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <code class="option">-r</code> option enables <span><strong class="command">host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein the behavior of a name server by making non-recursive queries and
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein expecting to receive answers to those queries that are usually
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User referrals to other name servers.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein By default, <span><strong class="command">host</strong></span> uses UDP when making
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein queries. The
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">-T</code> option makes it use a TCP connection when querying
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein the name server. TCP will be automatically selected for queries that
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User require it, such as zone transfer (AXFR) requests.
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt The <code class="option">-4</code> option forces <span><strong class="command">host</strong></span> to only
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt use IPv4 query transport. The <code class="option">-6</code> option forces
852ccdd42a71550c974111b49415204ffeca6573Automatic Updater <span><strong class="command">host</strong></span> to only use IPv6 query transport.
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt The <code class="option">-t</code> option is used to select the query type.
3cddb2c552ee6582e8db0849c28747f6b6ca57feAutomatic Updater <em class="parameter"><code>type</code></em> can be any recognized query
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt <span><strong class="command">host</strong></span> automatically selects an appropriate
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User type. By default, it looks for A, AAAA, and MX records, but if the
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <code class="option">-C</code> option was given, queries will be made for SOA
66f25f2ceeb589e67efe7af2413baaa3426b0042Automatic Updater records, and if <em class="parameter"><code>name</code></em> is a
66f25f2ceeb589e67efe7af2413baaa3426b0042Automatic Updater dotted-decimal IPv4
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt address or colon-delimited IPv6 address, <span><strong class="command">host</strong></span> will
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt query for PTR records. If a query type of IXFR is chosen the starting
14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt serial number can be specified by appending an equal followed by the
66f25f2ceeb589e67efe7af2413baaa3426b0042Automatic Updater starting serial number (e.g. -t IXFR=12345678).
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The time to wait for a reply can be controlled through the
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <code class="option">-W</code> and <code class="option">-w</code> options. The
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <code class="option">-W</code> option makes <span><strong class="command">host</strong></span>
38417cbfb1a328c20b5b723b8584a02c57f88897Automatic Updater <em class="parameter"><code>wait</code></em> seconds. If <em class="parameter"><code>wait</code></em>
38417cbfb1a328c20b5b723b8584a02c57f88897Automatic Updater is less than one, the wait interval is set to one second. When the
38417cbfb1a328c20b5b723b8584a02c57f88897Automatic Updater <code class="option">-w</code> option is used, <span><strong class="command">host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein effectively wait forever for a reply. The time to wait for a response
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User will be set to the number of seconds given by the hardware's maximum
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User value for an integer quantity. By default, <span><strong class="command">host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein will wait for 5 seconds for UDP responses and 10 seconds for TCP
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein connections. These defaults can be overridden by the
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <em class="parameter"><code>timeout</code></em> option in
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <code class="filename">/etc/resolv.conf</code>.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The <code class="option">-s</code> option tells <span><strong class="command">host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span class="emphasis"><em>not</em></span> to send the query to the next nameserver
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein if any server responds with a SERVFAIL response, which is the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein reverse of normal stub resolver behavior.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The <code class="option">-m</code> can be used to set the memory usage debugging
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <em class="parameter"><code>record</code></em>, <em class="parameter"><code>usage</code></em> and
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The <code class="option">-V</code> option causes <span><strong class="command">host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein to print the version number and exit.
3a5fe5abf08f16b8d31ab8ee9a788063110ef000Automatic Updater<a name="id2616551"></a><h2>IDN SUPPORT</h2>
3a5fe5abf08f16b8d31ab8ee9a788063110ef000Automatic Updater If <span><strong class="command">host</strong></span> has been built with IDN (internationalized
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein domain name) support, it can accept and display non-ASCII domain names.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <span><strong class="command">host</strong></span> appropriately converts character encoding of
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User domain name before sending a request to DNS server or displaying a
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein reply from the server.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein If you'd like to turn off the IDN support for some reason, defines
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein the <code class="envar">IDN_DISABLE</code> environment variable.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The IDN support is disabled if the variable is set when
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span><strong class="command">host</strong></span> runs.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<p><code class="filename">/etc/resolv.conf</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<p><span class="citerefentry"><span class="refentrytitle">dig</span>(1)</span>,
b05bdb520d83f7ecaad708fe305268c3420be01dMark Andrews <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>.
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