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794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User - Copyright (C) 2004, 2005, 2007-2009, 2014 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
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2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User — DNS lookup utility
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <div class="refsynopsisdiv" title="Synopsis">
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User [<code class="option">-c <em class="replaceable"><code>class</code></em></code>]
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User [<code class="option">-N <em class="replaceable"><code>ndots</code></em></code>]
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User [<code class="option">-R <em class="replaceable"><code>number</code></em></code>]
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User [<code class="option">-t <em class="replaceable"><code>type</code></em></code>]
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User [<code class="option">-W <em class="replaceable"><code>wait</code></em></code>]
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User [<code class="option">-m <em class="replaceable"><code>flag</code></em></code>]
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<a name="idp60793808"></a><h2>DESCRIPTION</h2>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox 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.
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox 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
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The <code class="option">-a</code> (all) option is equivalent to setting the
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <code class="option">-v</code> option and asking <span class="command"><strong>host</strong></span> to make
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein a query of type ANY.
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User When the <code class="option">-C</code> option is used, <span class="command"><strong>host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein will attempt to display the SOA records for zone
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>name</code></em> from all the listed
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein authoritative name
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein servers for that zone. The list of name servers is defined by the NS
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein records that are found for the zone.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The <code class="option">-c</code> option instructs to make a DNS query of class
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>class</code></em>. This can be used to lookup
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Chaosnet class resource records. The default class is IN (Internet).
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User Verbose output is generated by <span class="command"><strong>host</strong></span> when
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">-d</code> or <code class="option">-v</code> option is used. The two
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein options are equivalent. They have been provided for backwards
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein compatibility. In previous versions, the <code class="option">-d</code> option
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein switched on debugging traces and <code class="option">-v</code> enabled verbose
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User output. Verbose output can also be enabled by setting the
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User <em class="parameter"><code>debug</code></em> option in
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User <code class="filename">/etc/resolv.conf</code>.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein List mode is selected by the <code class="option">-l</code> option. This makes
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <span class="command"><strong>host</strong></span> perform a zone transfer for zone
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>name</code></em>. Transfer the zone printing out
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein and address records (A/AAAA). If combined with <code class="option">-a</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein 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.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein 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
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein in <em class="parameter"><code>name</code></em> for it to be considered
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein absolute. The
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein default value is that defined using the ndots statement in
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <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>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein or <span class="type">domain</span> directive in
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The number of UDP retries for a lookup can be changed with the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">-R</code> option. <em class="parameter"><code>number</code></em>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User how many times <span class="command"><strong>host</strong></span> will repeat a query
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User not get answered. If
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>number</code></em> is negative or zero, the
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User retries will default to 1. The default value is 1, or
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User the value of the <em class="parameter"><code>attempts</code></em> option in
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User <code class="filename">/etc/resolv.conf</code>, if set.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Non-recursive queries can be made via the <code class="option">-r</code> option.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Setting this option clears the <span class="type">RD</span> — recursion
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User desired — bit in the query which <span class="command"><strong>host</strong></span> makes.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein This should mean that the name server receiving the query will not
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein attempt to resolve <em class="parameter"><code>name</code></em>. The
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <code class="option">-r</code> option enables <span class="command"><strong>host</strong></span>
d71e2e0c61df16ff37c9934c371a4a60c08974f7Mark Andrews the behavior of a name server by making non-recursive queries and
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein expecting to receive answers to those queries that are usually
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein referrals to other name servers.
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User By default, <span class="command"><strong>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
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein require it, such as zone transfer (AXFR) requests.
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User The <code class="option">-4</code> option forces <span class="command"><strong>host</strong></span> to only
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein use IPv4 query transport. The <code class="option">-6</code> option forces
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <span class="command"><strong>host</strong></span> to only use IPv6 query transport.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The <code class="option">-t</code> option is used to select the query type.
d71e2e0c61df16ff37c9934c371a4a60c08974f7Mark Andrews <em class="parameter"><code>type</code></em> can be any recognized query
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein type: CNAME,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <span class="command"><strong>host</strong></span> automatically selects an appropriate
9fbbfb5757a1e3e86d7dea62c4e63ffc2303ca2bAutomatic Updater type. By default, it looks for A, AAAA, and MX records, but if the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">-C</code> option was given, queries will be made for SOA
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein records, and if <em class="parameter"><code>name</code></em> is a
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein dotted-decimal IPv4
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User address or colon-delimited IPv6 address, <span class="command"><strong>host</strong></span> will
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein query for PTR records. If a query type of IXFR is chosen the starting
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein serial number can be specified by appending an equal followed by the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein starting serial number (e.g. -t IXFR=12345678).
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The time to wait for a reply can be controlled through the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="option">-W</code> and <code class="option">-w</code> options. The
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <code class="option">-W</code> option makes <span class="command"><strong>host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>wait</code></em> seconds. If <em class="parameter"><code>wait</code></em>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein is less than one, the wait interval is set to one second. When the
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <code class="option">-w</code> option is used, <span class="command"><strong>host</strong></span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein effectively wait forever for a reply. The time to wait for a response
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein will be set to the number of seconds given by the hardware's maximum
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User value for an integer quantity. By default, <span class="command"><strong>host</strong></span>
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User will wait for 5 seconds for UDP responses and 10 seconds for TCP
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User connections. These defaults can be overridden by the
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User <em class="parameter"><code>timeout</code></em> option in
f39512a917cdd06c611d366603374f6ef570c80eTinderbox User <code class="filename">/etc/resolv.conf</code>.
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User The <code class="option">-s</code> option tells <span class="command"><strong>host</strong></span>
a057e8e33baa5fa369be28a9680585200ce3ff73Mark Andrews <span class="emphasis"><em>not</em></span> to send the query to the next nameserver
a057e8e33baa5fa369be28a9680585200ce3ff73Mark Andrews if any server responds with a SERVFAIL response, which is the
d71e2e0c61df16ff37c9934c371a4a60c08974f7Mark Andrews reverse of normal stub resolver behavior.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The <code class="option">-m</code> can be used to set the memory usage debugging
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>record</code></em>, <em class="parameter"><code>usage</code></em> and
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User The <code class="option">-V</code> option causes <span class="command"><strong>host</strong></span>
b46346eb3026ba4bebc093bc93cfe159131e541eTinderbox User to print the version number and exit.
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<a name="idp60873168"></a><h2>IDN SUPPORT</h2>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User If <span class="command"><strong>host</strong></span> has been built with IDN (internationalized
057cafaa3df7be7a6dcca71fbaf8fb498fd83518Mark Andrews 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.
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User <p><code class="filename">/etc/resolv.conf</code>