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div class="refentry" lang="en">
5666N/A<
p>host — DNS lookup utility</
p>
224N/A<
div class="refsynopsisdiv">
224N/A<
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>
844N/A<
div class="refsect1" lang="en">
2624N/A<
a name="id2543446"></
a><
h2>DESCRIPTION</
h2>
224N/A<
p><
span><
strong class="command">host</
strong></
span>
224N/A is a simple utility for performing DNS lookups.
1258N/A It is normally used to convert names to IP addresses and vice versa.
224N/A When no arguments or options are given,
5198N/A <
span><
strong class="command">host</
strong></
span>
2899N/A prints a short summary of its command line arguments and options.
3817N/A<
p><
em class="parameter"><
code>name</
code></
em> is the domain name that is to be
224N/A up. It can also be a dotted-decimal IPv4 address or a colon-delimited
5666N/A IPv6 address, in which case <
span><
strong class="command">host</
strong></
span> will by
5666N/A perform a reverse lookup for that address.
5666N/A <
em class="parameter"><
code>server</
code></
em> is an optional argument which
5666N/A the name or IP address of the name server that <
span><
strong class="command">host</
strong></
span>
5666N/A should query instead of the server or servers listed in
5666N/A The <
code class="option">-a</
code> (all) option is equivalent to setting the
5666N/A <
code class="option">-v</
code> option and asking <
span><
strong class="command">host</
strong></
span> to make
5666N/A When the <
code class="option">-C</
code> option is used, <
span><
strong class="command">host</
strong></
span>
224N/A will attempt to display the SOA records for zone
5666N/A <
em class="parameter"><
code>name</
code></
em> from all the listed
224N/A servers for that zone. The list of name servers is defined by the NS
5666N/A records that are found for the zone.
5666N/A The <
code class="option">-c</
code> option instructs to make a DNS query of class
5666N/A <
em class="parameter"><
code>class</
code></
em>. This can be used to lookup
224N/A Chaosnet class resource records. The default class is IN (Internet).
224N/A Verbose output is generated by <
span><
strong class="command">host</
strong></
span> when
5666N/A <
code class="option">-d</
code> or <
code class="option">-v</
code> option is used. The two
5666N/A options are equivalent. They have been provided for backwards
224N/A compatibility. In previous versions, the <
code class="option">-d</
code> option
224N/A switched on debugging traces and <
code class="option">-v</
code> enabled verbose
5666N/A List mode is selected by the <
code class="option">-l</
code> option. This makes
5666N/A <
span><
strong class="command">host</
strong></
span> perform a zone transfer for zone
5666N/A <
em class="parameter"><
code>name</
code></
em>. Transfer the zone printing out
5666N/A and address records (
A/
AAAA). If combined with <
code class="option">-a</
code>
5666N/A all records will be printed.
5666N/A The <
code class="option">-i</
code>
5666N/A option specifies that reverse lookups of IPv6 addresses should
5666N/A The <
code class="option">-N</
code> option sets the number of dots that have to be
224N/A in <
em class="parameter"><
code>name</
code></
em> for it to be considered
5666N/A default value is that defined using the ndots statement in
224N/A present. Names with fewer dots are interpreted as relative names and
5666N/A will be searched for in the domains listed in the <
span class="type">search</
span>
224N/A or <
span class="type">domain</
span> directive in
5666N/A The number of UDP retries for a lookup can be changed with the
5666N/A <
code class="option">-R</
code> option. <
em class="parameter"><
code>number</
code></
em>
5666N/A how many times <
span><
strong class="command">host</
strong></
span> will repeat a query
5666N/A not get answered. The default number of retries is 1. If
5666N/A <
em class="parameter"><
code>number</
code></
em> is negative or zero, the
5666N/A Non-recursive queries can be made via the <
code class="option">-r</
code> option.
5666N/A Setting this option clears the <
span class="type">RD</
span> — recursion
5666N/A desired — bit in the query which <
span><
strong class="command">host</
strong></
span> makes.
224N/A This should mean that the name server receiving the query will not
224N/A attempt to resolve <
em class="parameter"><
code>name</
code></
em>. The
224N/A <
code class="option">-r</
code> option enables <
span><
strong class="command">host</
strong></
span>
5666N/A the behavior of a name server by making non-recursive queries and
5666N/A expecting to receive answers to those queries that are usually
224N/A referrals to other name servers.
224N/A By default, <
span><
strong class="command">host</
strong></
span> uses UDP when making
224N/A <
code class="option">-T</
code> option makes it use a TCP connection when querying
224N/A the name server. TCP will be automatically selected for queries that
224N/A require it, such as zone transfer (AXFR) requests.
5666N/A The <
code class="option">-4</
code> option forces <
span><
strong class="command">host</
strong></
span> to only
5666N/A use IPv4 query transport. The <
code class="option">-6</
code> option forces
5666N/A <
span><
strong class="command">host</
strong></
span> to only use IPv6 query transport.
224N/A The <
code class="option">-t</
code> option is used to select the query type.
5666N/A <
em class="parameter"><
code>type</
code></
em> can be any recognized query
5666N/A NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
5666N/A <
span><
strong class="command">host</
strong></
span> automatically selects an appropriate
5666N/A type. By default, it looks for A, AAAA, and MX records, but if the
5666N/A <
code class="option">-C</
code> option was given, queries will be made for SOA
5666N/A records, and if <
em class="parameter"><
code>name</
code></
em> is a
5666N/A address or colon-delimited IPv6 address, <
span><
strong class="command">host</
strong></
span> will
5666N/A query for PTR records. If a query type of IXFR is chosen the starting
5666N/A serial number can be specified by appending an equal followed by the
5666N/A starting serial number (
e.g. -t IXFR=12345678).
5666N/A The time to wait for a reply can be controlled through the
5666N/A <
code class="option">-W</
code> and <
code class="option">-w</
code> options. The
224N/A <
code class="option">-W</
code> option makes <
span><
strong class="command">host</
strong></
span>
5666N/A <
em class="parameter"><
code>wait</
code></
em> seconds. If <
em class="parameter"><
code>wait</
code></
em>
5666N/A is less than one, the wait interval is set to one second. When the
5666N/A <
code class="option">-w</
code> option is used, <
span><
strong class="command">host</
strong></
span>
5666N/A effectively wait forever for a reply. The time to wait for a response
5666N/A will be set to the number of seconds given by the hardware's maximum
224N/A value for an integer quantity.
5666N/A The <
code class="option">-s</
code> option tells <
span><
strong class="command">host</
strong></
span>
224N/A <
span class="emphasis"><
em>not</
em></
span> to send the query to the next nameserver
5666N/A if any server responds with a SERVFAIL response, which is the
224N/A reverse of normal stub resolver behavior.
5666N/A The <
code class="option">-m</
code> can be used to set the memory usage debugging
3817N/A <
em class="parameter"><
code>record</
code></
em>, <
em class="parameter"><
code>usage</
code></
em> and
3817N/A <
em class="parameter"><
code>trace</
code></
em>.
5667N/A The <
code class="option">-V</
code> option causes <
span><
strong class="command">host</
strong></
span>
3817N/A to print the version number and exit.
5667N/A<
div class="refsect1" lang="en">
<
a name="id2543822"></
a><
h2>IDN SUPPORT</
h2>
If <
span><
strong class="command">host</
strong></
span> has been built with IDN (internationalized
domain name) support, it can accept and display non-ASCII domain names.
<
span><
strong class="command">host</
strong></
span> appropriately converts character encoding of
domain name before sending a request to DNS server or displaying a
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><
strong class="command">host</
strong></
span> runs.
<
div class="refsect1" lang="en">
<
a name="id2543845"></
a><
h2>FILES</
h2>
<
div class="refsect1" lang="en">
<
a name="id2543857"></
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>.