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3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User - Copyright (C) 2004, 2005, 2007-2009, 2014-2016 Internet Systems Consortium, Inc. ("ISC")
75c0816e8295e180f4bc7f10db3d0d880383bc1cMark Andrews - Copyright (C) 2000-2002 Internet Software Consortium.
4a14ce5ba00ab7bc55c99ffdcf59c7a4ab902721Automatic Updater - Permission to use, copy, modify, and/or distribute this software for any
fb84f9014321c5f33c4682de5661b579fcde318fAndreas Gustafsson - purpose with or without fee is hereby granted, provided that the above
fb84f9014321c5f33c4682de5661b579fcde318fAndreas Gustafsson - copyright notice and this permission notice appear in all copies.
9016767f4e15191b7c763b8a4ad36a57dc2705a2Mark Andrews - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
9016767f4e15191b7c763b8a4ad36a57dc2705a2Mark Andrews - 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,
9016767f4e15191b7c763b8a4ad36a57dc2705a2Mark Andrews - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
9016767f4e15191b7c763b8a4ad36a57dc2705a2Mark Andrews - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
9016767f4e15191b7c763b8a4ad36a57dc2705a2Mark Andrews - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
9016767f4e15191b7c763b8a4ad36a57dc2705a2Mark Andrews - PERFORMANCE OF THIS SOFTWARE.
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fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry">
5a4557e8de2951a2796676b5ec4b6a90caa5be14Mark Andrews<a name="man.host"></a><div class="titlepage"></div>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox 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>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<p><span class="command"><strong>host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein is a simple utility for performing DNS lookups.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein It is normally used to convert names to IP addresses and vice versa.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein When no arguments or options are given,
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <span class="command"><strong>host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein prints a short summary of its command line arguments and options.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<p><em class="parameter"><code>name</code></em> is the domain name that is to be
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein up. It can also be a dotted-decimal IPv4 address or a colon-delimited
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User IPv6 address, in which case <span class="command"><strong>host</strong></span> will by
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein perform a reverse lookup for that address.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>server</code></em> is an optional argument which
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User the name or IP address of the name server that <span class="command"><strong>host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein should query instead of the server or servers listed in
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User<div class="variablelist"><dl class="variablelist">
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Use IPv4 only for query transport.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User See also the <code class="option">-6</code> option.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Use IPv6 only for query transport.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User See also the <code class="option">-4</code> option.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User "All". The <code class="option">-a</code> option is normally equivalent
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User to <code class="option">-v</code> <code class="option">-t</code> <code class="literal">ANY</code>.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User It also affects the behaviour of the <code class="option">-l</code>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User list zone option.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User<dt><span class="term">-c <em class="replaceable"><code>class</code></em></span></dt>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Query class: This can be used to lookup Hesiod or Chaosnet
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User class resource records. The default class is IN
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Check consistency: <span class="command"><strong>host</strong></span> will query the
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User SOA records for zone <em class="parameter"><code>name</code></em> from all
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User the listed authoritative name servers for that zone. The
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User list of name servers is defined by the NS records that are
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User found for the zone.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Print debugging traces.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Equivalent to the <code class="option">-v</code> verbose option.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Use the IP6.INT domain for reverse lookups of IPv6
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User addresses as defined in RFC1886 and deprecated in RFC4159.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User The default is to use IP6.ARPA as specified in RFC3596.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User The <span class="command"><strong>host</strong></span> performs a zone transfer of
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User zone <em class="parameter"><code>name</code></em> and prints out the NS,
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Together, the <code class="option">-l</code> <code class="option">-a</code>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User options print all records in the zone.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User<dt><span class="term">-N <em class="replaceable"><code>ndots</code></em></span></dt>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User The number of dots that have to be
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User in <em class="parameter"><code>name</code></em> for it to be considered
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User absolute. The default value is that defined using the
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User ndots statement in <code class="filename">/etc/resolv.conf</code>,
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User or 1 if no ndots statement is present. Names with fewer
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User dots are interpreted as relative names and will be
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User searched for in the domains listed in
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User the <span class="type">search</span> or <span class="type">domain</span> directive
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User in <code class="filename">/etc/resolv.conf</code>.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Non-recursive query:
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Setting this option clears the <span class="type">RD</span> —
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User recursion desired — bit in the query. This should
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User mean that the name server receiving the query will not
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User attempt to resolve <em class="parameter"><code>name</code></em>.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User enables <span class="command"><strong>host</strong></span> to mimic the behavior of a
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User name server by making non-recursive queries and expecting
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User to receive answers to those queries that can be
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User referrals to other name servers.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User<dt><span class="term">-R <em class="replaceable"><code>number</code></em></span></dt>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Number of retries for UDP queries:
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User If <em class="parameter"><code>number</code></em> is negative or zero, the
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User number of retries will default to 1. The default value is
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User 1, or the value of the <em class="parameter"><code>attempts</code></em>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User option in <code class="filename">/etc/resolv.conf</code>, if set.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Do <span class="emphasis"><em>not</em></span> send the query to the next
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User nameserver if any server responds with a SERVFAIL
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User response, which is the reverse of normal stub resolver
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User<dt><span class="term">-t <em class="replaceable"><code>type</code></em></span></dt>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User the <em class="parameter"><code>type</code></em> argument can be any
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User recognized query type: CNAME, NS, SOA, TXT, DNSKEY, AXFR, etc.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User When no query type is specified, <span class="command"><strong>host</strong></span>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User automatically selects an appropriate query type. By default, it
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User looks for A, AAAA, and MX records.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User If the <code class="option">-C</code> option is given, queries will
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User be made for SOA records.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User If <em class="parameter"><code>name</code></em> is a dotted-decimal IPv4
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User address or colon-delimited IPv6
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User address, <span class="command"><strong>host</strong></span> will query for PTR
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User If a query type of IXFR is chosen the starting serial
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User number can be specified by appending an equal followed by
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User the starting serial number
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User (e.g. <code class="option">-t</code> <code class="literal">IXFR=12345678</code>).
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User By default, <span class="command"><strong>host</strong></span> uses UDP when making
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User queries. The <code class="option">-T</code> option makes it use a TCP
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User connection when querying the name server. TCP will be
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User automatically selected for queries that require it, such
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User as zone transfer (AXFR) requests.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User<dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Memory usage debugging: the flag can
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User be <em class="parameter"><code>record</code></em>, <em class="parameter"><code>usage</code></em>,
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User or <em class="parameter"><code>trace</code></em>. You can specify
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User the <code class="option">-m</code> option more than once to set
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User multiple flags.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Verbose output.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Equivalent to the <code class="option">-d</code> debug option.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Verbose output can also be enabled by setting
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User the <em class="parameter"><code>debug</code></em> option
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User in<code class="filename">/etc/resolv.conf</code>.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Print the version number and exit.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Wait forever: the query timeout is set to the maximum possible.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User See also the <code class="option">-W</code> option.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User<dt><span class="term">-W <em class="replaceable"><code>wait</code></em></span></dt>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User Timeout: wait for up to <em class="parameter"><code>wait</code></em>
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User seconds for a reply. If <em class="parameter"><code>wait</code></em> is
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User less than one, the wait interval is set to one second.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User By default, <span class="command"><strong>host</strong></span> will wait for 5
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User seconds for UDP responses and 10 seconds for TCP
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User connections. These defaults can be overridden by
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User the <em class="parameter"><code>timeout</code></em> option
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User in <code class="filename">/etc/resolv.conf</code>.
3241ddcf9354c5ab50f4df5a656e72a5c68e172bTinderbox User See also the <code class="option">-w</code> option.
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User If <span class="command"><strong>host</strong></span> has been built with IDN (internationalized
9d557856c2a19ec95ee73245f60a92f8675cf5baTinderbox User domain name) support, it can accept and display non-ASCII domain names.
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <span class="command"><strong>host</strong></span> appropriately converts character encoding of
057cafaa3df7be7a6dcca71fbaf8fb498fd83518Mark Andrews domain name before sending a request to DNS server or displaying a
057cafaa3df7be7a6dcca71fbaf8fb498fd83518Mark Andrews reply from the server.
057cafaa3df7be7a6dcca71fbaf8fb498fd83518Mark Andrews If you'd like to turn off the IDN support for some reason, defines
057cafaa3df7be7a6dcca71fbaf8fb498fd83518Mark Andrews the <code class="envar">IDN_DISABLE</code> environment variable.
057cafaa3df7be7a6dcca71fbaf8fb498fd83518Mark Andrews The IDN support is disabled if the variable is set when
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <span class="command"><strong>host</strong></span> runs.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<p><code class="filename">/etc/resolv.conf</code>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<p><span class="citerefentry"><span class="refentrytitle">dig</span>(1)</span>,
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>.