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1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<div class="refentry">
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<a name="man.host"></a><div class="titlepage"></div>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <div class="refnamediv">
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<h2>Name</h2>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User host
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User &#8212; DNS lookup utility
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User</div>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <div class="refsynopsisdiv">
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<h2>Synopsis</h2>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <div class="cmdsynopsis"><p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <code class="command">host</code>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [<code class="option">-aCdlnrsTUwv</code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [<code class="option">-c <em class="replaceable"><code>class</code></em></code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [<code class="option">-N <em class="replaceable"><code>ndots</code></em></code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [<code class="option">-R <em class="replaceable"><code>number</code></em></code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [<code class="option">-t <em class="replaceable"><code>type</code></em></code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [<code class="option">-W <em class="replaceable"><code>wait</code></em></code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [<code class="option">-m <em class="replaceable"><code>flag</code></em></code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [<code class="option">-4</code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User | [<code class="option">-6</code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User ]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [<code class="option">-v</code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [<code class="option">-V</code>]
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User {name}
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User [server]
7e71f05d8643aca84914437c900cb716444507e4Tinderbox User </p></div>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </div>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User <div class="refsection">
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<a name="id-1.14.4.7"></a><h2>DESCRIPTION</h2>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p><span class="command"><strong>host</strong></span>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User is a simple utility for performing DNS lookups.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User It is normally used to convert names to IP addresses and vice versa.
7e71f05d8643aca84914437c900cb716444507e4Tinderbox User When no arguments or options are given,
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <span class="command"><strong>host</strong></span>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User prints a short summary of its command line arguments and options.
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p><em class="parameter"><code>name</code></em> is the domain name that is to be
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User looked
bfb7b680bf88c1fdd9949197b71c512c532280a4Tinderbox User up. It can also be a dotted-decimal IPv4 address or a colon-delimited
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User IPv6 address, in which case <span class="command"><strong>host</strong></span> will by
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User default
bfb7b680bf88c1fdd9949197b71c512c532280a4Tinderbox User perform a reverse lookup for that address.
bfb7b680bf88c1fdd9949197b71c512c532280a4Tinderbox User <em class="parameter"><code>server</code></em> is an optional argument which
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User is either
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User the name or IP address of the name server that <span class="command"><strong>host</strong></span>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User should query instead of the server or servers listed in
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <code class="filename">/etc/resolv.conf</code>.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </div>
bfb7b680bf88c1fdd9949197b71c512c532280a4Tinderbox User
bfb7b680bf88c1fdd9949197b71c512c532280a4Tinderbox User <div class="refsection">
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<a name="id-1.14.4.8"></a><h2>OPTIONS</h2>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User <div class="variablelist"><dl class="variablelist">
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dt><span class="term">-4</span></dt>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User <p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User Use IPv4 only for query transport.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User See also the <code class="option">-6</code> option.
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </dd>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dt><span class="term">-6</span></dt>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User <p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User Use IPv6 only for query transport.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User See also the <code class="option">-4</code> option.
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </dd>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dt><span class="term">-a</span></dt>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User <p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User "All". The <code class="option">-a</code> option is normally equivalent
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User to <code class="option">-v -t <code class="literal">ANY</code></code>.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User It also affects the behaviour of the <code class="option">-l</code>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User list zone option.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<dt><span class="term">-c <em class="replaceable"><code>class</code></em></span></dt>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User <p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User Query class: This can be used to lookup HS (Hesiod) or CH
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User (Chaosnet) class resource records. The default class is IN
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User (Internet).
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </dd>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dt><span class="term">-C</span></dt>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User <p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User Check consistency: <span class="command"><strong>host</strong></span> will query the
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User SOA records for zone <em class="parameter"><code>name</code></em> from all
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User the listed authoritative name servers for that zone. The
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User list of name servers is defined by the NS records that are
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User found for the zone.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </dd>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dt><span class="term">-d</span></dt>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User <p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User Print debugging traces.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User Equivalent to the <code class="option">-v</code> verbose option.
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<dt><span class="term">-i</span></dt>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dd>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User Obsolete.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User Use the IP6.INT domain for reverse lookups of IPv6
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User addresses as defined in RFC1886 and deprecated in RFC4159.
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User The default is to use IP6.ARPA as specified in RFC3596.
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </dd>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dt><span class="term">-l</span></dt>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<dd>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User List zone:
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User The <span class="command"><strong>host</strong></span> command performs a zone transfer of
7e71f05d8643aca84914437c900cb716444507e4Tinderbox User zone <em class="parameter"><code>name</code></em> and prints out the NS,
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User PTR and address records (A/AAAA).
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User Together, the <code class="option">-l -a</code>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User options print all records in the zone.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User </dd>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dt><span class="term">-N <em class="replaceable"><code>ndots</code></em></span></dt>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User<dd>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User The number of dots that have to be
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User in <em class="parameter"><code>name</code></em> for it to be considered
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User absolute. The default value is that defined using the
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User ndots statement in <code class="filename">/etc/resolv.conf</code>,
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User or 1 if no ndots statement is present. Names with fewer
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User dots are interpreted as relative names and will be
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User searched for in the domains listed in
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User the <span class="type">search</span> or <span class="type">domain</span> directive
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User in <code class="filename">/etc/resolv.conf</code>.
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<dt><span class="term">-r</span></dt>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User <p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User Non-recursive query:
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User Setting this option clears the RD (recursion desired) bit
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User in the query. This should mean that the name server
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User receiving the query will not attempt to
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User resolve <em class="parameter"><code>name</code></em>.
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User The <code class="option">-r</code> option
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User enables <span class="command"><strong>host</strong></span> to mimic the behavior of a
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User name server by making non-recursive queries and expecting
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User to receive answers to those queries that can be
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User referrals to other name servers.
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User </dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User<dt><span class="term">-R <em class="replaceable"><code>number</code></em></span></dt>
c313914d0e66b20969215e519bbf2ab4ecf39512Tinderbox User<dd>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User <p>
1e9517ea2156b990be21f44676d3370318eacf17Tinderbox User Number of retries for UDP queries:
If <em class="parameter"><code>number</code></em> is negative or zero, the
number of retries will default to 1. The default value is
1, or the value of the <em class="parameter"><code>attempts</code></em>
option in <code class="filename">/etc/resolv.conf</code>, if set.
</p>
</dd>
<dt><span class="term">-s</span></dt>
<dd>
<p>
Do <span class="emphasis"><em>not</em></span> send the query to the next
nameserver if any server responds with a SERVFAIL
response, which is the reverse of normal stub resolver
behavior.
</p>
</dd>
<dt><span class="term">-t <em class="replaceable"><code>type</code></em></span></dt>
<dd>
<p>
Query type:
The <em class="parameter"><code>type</code></em> argument can be any
recognized query type: CNAME, NS, SOA, TXT, DNSKEY, AXFR, etc.
</p>
<p>
When no query type is specified, <span class="command"><strong>host</strong></span>
automatically selects an appropriate query type. By default, it
looks for A, AAAA, and MX records.
If the <code class="option">-C</code> option is given, queries will
be made for SOA records.
If <em class="parameter"><code>name</code></em> is a dotted-decimal IPv4
address or colon-delimited IPv6
address, <span class="command"><strong>host</strong></span> will query for PTR
records.
</p>
<p>
If a query type of IXFR is chosen the starting serial
number can be specified by appending an equal followed by
the starting serial number
(like <code class="option">-t <code class="literal">IXFR=12345678</code></code>).
</p>
</dd>
<dt>
<span class="term">-T, </span><span class="term">-U</span>
</dt>
<dd>
<p>
TCP/UDP:
By default, <span class="command"><strong>host</strong></span> uses UDP when making
queries. The <code class="option">-T</code> option makes it use a TCP
connection when querying the name server. TCP will be
automatically selected for queries that require it, such
as zone transfer (AXFR) requests. Type ANY queries default
to TCP but can be forced to UDP initially using <code class="option">-U</code>.
</p>
</dd>
<dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
<dd>
<p>
Memory usage debugging: the flag can
be <em class="parameter"><code>record</code></em>, <em class="parameter"><code>usage</code></em>,
or <em class="parameter"><code>trace</code></em>. You can specify
the <code class="option">-m</code> option more than once to set
multiple flags.
</p>
</dd>
<dt><span class="term">-v</span></dt>
<dd>
<p>
Verbose output.
Equivalent to the <code class="option">-d</code> debug option.
Verbose output can also be enabled by setting
the <em class="parameter"><code>debug</code></em> option
in <code class="filename">/etc/resolv.conf</code>.
</p>
</dd>
<dt><span class="term">-V</span></dt>
<dd>
<p>
Print the version number and exit.
</p>
</dd>
<dt><span class="term">-w</span></dt>
<dd>
<p>
Wait forever: The query timeout is set to the maximum possible.
See also the <code class="option">-W</code> option.
</p>
</dd>
<dt><span class="term">-W <em class="replaceable"><code>wait</code></em></span></dt>
<dd>
<p>
Timeout: Wait for up to <em class="parameter"><code>wait</code></em>
seconds for a reply. If <em class="parameter"><code>wait</code></em> is
less than one, the wait interval is set to one second.
</p>
<p>
By default, <span class="command"><strong>host</strong></span> will wait for 5
seconds for UDP responses and 10 seconds for TCP
connections. These defaults can be overridden by
the <em class="parameter"><code>timeout</code></em> option
in <code class="filename">/etc/resolv.conf</code>.
</p>
<p>
See also the <code class="option">-w</code> option.
</p>
</dd>
</dl></div>
</div>
<div class="refsection">
<a name="id-1.14.4.9"></a><h2>IDN SUPPORT</h2>
<p>
If <span class="command"><strong>host</strong></span> has been built with IDN (internationalized
domain name) support, it can accept and display non-ASCII domain names.
<span class="command"><strong>host</strong></span> appropriately converts character encoding of
domain name before sending a request to DNS server or displaying a
reply from the server.
If you'd like to turn off the IDN support for some reason, defines
the <code class="envar">IDN_DISABLE</code> environment variable.
The IDN support is disabled if the variable is set when
<span class="command"><strong>host</strong></span> runs.
</p>
</div>
<div class="refsection">
<a name="id-1.14.4.10"></a><h2>FILES</h2>
<p><code class="filename">/etc/resolv.conf</code>
</p>
</div>
<div class="refsection">
<a name="id-1.14.4.11"></a><h2>SEE ALSO</h2>
<p><span class="citerefentry">
<span class="refentrytitle">dig</span>(1)
</span>,
<span class="citerefentry">
<span class="refentrytitle">named</span>(8)
</span>.
</p>
</div>
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