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5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync - Copyright (C) 2004-2013 Internet Systems Consortium, Inc. ("ISC")
17d67aeb3722c094c6493a3e9a9d0cdfb9453ecdvboxsync - Copyright (C) 2000-2003 Internet Software Consortium.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync - Permission to use, copy, modify, and/or distribute this software for any
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync - purpose with or without fee is hereby granted, provided that the above
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync - copyright notice and this permission notice appear in all copies.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync - PERFORMANCE OF THIS SOFTWARE.
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3d8242e90019d302159795040e410b3d774a4b0bvboxsync<a name="man.host"></a><div class="titlepage"></div>
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync<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>
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync<p><span><strong class="command">host</strong></span>
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync is a simple utility for performing DNS lookups.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync It is normally used to convert names to IP addresses and vice versa.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync When no arguments or options are given,
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync prints a short summary of its command line arguments and options.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync<p><em class="parameter"><code>name</code></em> is the domain name that is to be
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync up. It can also be a dotted-decimal IPv4 address or a colon-delimited
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync IPv6 address, in which case <span><strong class="command">host</strong></span> will by
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync perform a reverse lookup for that address.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <em class="parameter"><code>server</code></em> is an optional argument which
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync the name or IP address of the name server that <span><strong class="command">host</strong></span>
f2ca52afeb0baed982c05e9d8591e0e4c7539dbdvboxsync should query instead of the server or servers listed in
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync The <code class="option">-a</code> (all) option is equivalent to setting the
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <code class="option">-v</code> option and asking <span><strong class="command">host</strong></span> to make
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync a query of type ANY.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync When the <code class="option">-C</code> option is used, <span><strong class="command">host</strong></span>
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync will attempt to display the SOA records for zone
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <em class="parameter"><code>name</code></em> from all the listed
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync authoritative name
3baadeafd9922582dad9b32431362e6296417dd8vboxsync servers for that zone. The list of name servers is defined by the NS
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync records that are found for the zone.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync The <code class="option">-c</code> option instructs to make a DNS query of class
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <em class="parameter"><code>class</code></em>. This can be used to lookup
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync Chaosnet class resource records. The default class is IN (Internet).
49c9958a74e4a297fb7ec141ee764e872430f4bavboxsync Verbose output is generated by <span><strong class="command">host</strong></span> when
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <code class="option">-d</code> or <code class="option">-v</code> option is used. The two
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync options are equivalent. They have been provided for backwards
faa254427e497bb7ee255b22581f40112025e92bvboxsync compatibility. In previous versions, the <code class="option">-d</code> option
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync switched on debugging traces and <code class="option">-v</code> enabled verbose
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync List mode is selected by the <code class="option">-l</code> option. This makes
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <span><strong class="command">host</strong></span> perform a zone transfer for zone
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <em class="parameter"><code>name</code></em>. Transfer the zone printing out
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync the NS, PTR
c215a948010614887014a258c1751602d8bf7781vboxsync and address records (A/AAAA). If combined with <code class="option">-a</code>
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync all records will be printed.
7c205843b5f25329b7bac4cb41e4c55a21c7aafevboxsync option specifies that reverse lookups of IPv6 addresses should
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync use the IP6.INT domain as defined in RFC1886.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync The default is to use IP6.ARPA.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync The <code class="option">-N</code> option sets the number of dots that have to be
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync in <em class="parameter"><code>name</code></em> for it to be considered
faa254427e497bb7ee255b22581f40112025e92bvboxsync absolute. The
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync default value is that defined using the ndots statement in
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <code class="filename">/etc/resolv.conf</code>, or 1 if no ndots
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync statement is
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync present. Names with fewer dots are interpreted as relative names and
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync will be searched for in the domains listed in the <span class="type">search</span>
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync The number of UDP retries for a lookup can be changed with the
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <code class="option">-R</code> option. <em class="parameter"><code>number</code></em>
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync how many times <span><strong class="command">host</strong></span> will repeat a query
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync not get answered. The default number of retries is 1. If
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <em class="parameter"><code>number</code></em> is negative or zero, the
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync retries will default to 1.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync Non-recursive queries can be made via the <code class="option">-r</code> option.
24713061a674af34286ac48ad1433329cdd404f2vboxsync Setting this option clears the <span class="type">RD</span> — recursion
24713061a674af34286ac48ad1433329cdd404f2vboxsync desired — bit in the query which <span><strong class="command">host</strong></span> makes.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync This should mean that the name server receiving the query will not
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync attempt to resolve <em class="parameter"><code>name</code></em>. The
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <code class="option">-r</code> option enables <span><strong class="command">host</strong></span>
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync the behavior of a name server by making non-recursive queries and
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync expecting to receive answers to those queries that are usually
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync referrals to other name servers.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync By default, <span><strong class="command">host</strong></span> uses UDP when making
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync queries. The
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <code class="option">-T</code> option makes it use a TCP connection when querying
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync the name server. TCP will be automatically selected for queries that
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync require it, such as zone transfer (AXFR) requests.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync The <code class="option">-4</code> option forces <span><strong class="command">host</strong></span> to only
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync use IPv4 query transport. The <code class="option">-6</code> option forces
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <span><strong class="command">host</strong></span> to only use IPv6 query transport.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync The <code class="option">-t</code> option is used to select the query type.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <em class="parameter"><code>type</code></em> can be any recognized query
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync type: CNAME,
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
9704f1d0180960069e2c4eb8fe2ddee350910e5dvboxsync <span><strong class="command">host</strong></span> automatically selects an appropriate
9704f1d0180960069e2c4eb8fe2ddee350910e5dvboxsync type. By default, it looks for A, AAAA, and MX records, but if the
9704f1d0180960069e2c4eb8fe2ddee350910e5dvboxsync <code class="option">-C</code> option was given, queries will be made for SOA
9704f1d0180960069e2c4eb8fe2ddee350910e5dvboxsync records, and if <em class="parameter"><code>name</code></em> is a
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync dotted-decimal IPv4
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync address or colon-delimited IPv6 address, <span><strong class="command">host</strong></span> will
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync query for PTR records. If a query type of IXFR is chosen the starting
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync serial number can be specified by appending an equal followed by the
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync starting serial number (e.g. -t IXFR=12345678).
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync The time to wait for a reply can be controlled through the
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <code class="option">-W</code> and <code class="option">-w</code> options. The
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <code class="option">-W</code> option makes <span><strong class="command">host</strong></span>
7c205843b5f25329b7bac4cb41e4c55a21c7aafevboxsync <em class="parameter"><code>wait</code></em> seconds. If <em class="parameter"><code>wait</code></em>
17d67aeb3722c094c6493a3e9a9d0cdfb9453ecdvboxsync is less than one, the wait interval is set to one second. When the
17d67aeb3722c094c6493a3e9a9d0cdfb9453ecdvboxsync <code class="option">-w</code> option is used, <span><strong class="command">host</strong></span>
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync effectively wait forever for a reply. The time to wait for a response
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync will be set to the number of seconds given by the hardware's maximum
c6adb272ec43d5eaadb1493cb2bf45f2f8adf588vboxsync value for an integer quantity.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync The <code class="option">-s</code> option tells <span><strong class="command">host</strong></span>
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <span class="emphasis"><em>not</em></span> to send the query to the next nameserver
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync if any server responds with a SERVFAIL response, which is the
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync reverse of normal stub resolver behavior.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync The <code class="option">-m</code> can be used to set the memory usage debugging
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <em class="parameter"><code>record</code></em>, <em class="parameter"><code>usage</code></em> and
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync If <span><strong class="command">host</strong></span> has been built with IDN (internationalized
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync domain name) support, it can accept and display non-ASCII domain names.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync <span><strong class="command">host</strong></span> appropriately converts character encoding of
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync domain name before sending a request to DNS server or displaying a
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync reply from the server.
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync If you'd like to turn off the IDN support for some reason, defines
5f9dfb422a6ed57822f9c0cb94fa7df8d24acc9bvboxsync the <code class="envar">IDN_DISABLE</code> environment variable.
c6adb272ec43d5eaadb1493cb2bf45f2f8adf588vboxsync The IDN support is disabled if the variable is set when
b28fef07fef379ecc179e0bc0d5d1be753e482b5vboxsync <span><strong class="command">host</strong></span> runs.
c6adb272ec43d5eaadb1493cb2bf45f2f8adf588vboxsync<p><span class="citerefentry"><span class="refentrytitle">dig</span>(1)</span>,
c6adb272ec43d5eaadb1493cb2bf45f2f8adf588vboxsync <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>.
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