host.docbook revision 30eec077db2bdcb6f2a0dc388a3cdde2ede75ec1
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk<!ENTITY mdash "—">]>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - Copyright (C) 2004, 2005, 2007-2009, 2014, 2015 Internet Systems Consortium, Inc. ("ISC")
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - Copyright (C) 2000-2002 Internet Software Consortium.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - Permission to use, copy, modify, and/or distribute this software for any
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - purpose with or without fee is hereby granted, provided that the above
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - copyright notice and this permission notice appear in all copies.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk - PERFORMANCE OF THIS SOFTWARE.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk<!-- Converted by db4-upgrade version 1.0 -->
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="man.host">
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <refentryinfo>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <corpauthor>Internet Systems Consortium, Inc.</corpauthor>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </refentryinfo>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <refnamediv>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </refnamediv>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <holder>Internet Systems Consortium, Inc. ("ISC")</holder>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </copyright>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </copyright>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <refsynopsisdiv>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-aCdlnrsTwv</option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-c <replaceable class="parameter">class</replaceable></option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-N <replaceable class="parameter">ndots</replaceable></option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-R <replaceable class="parameter">number</replaceable></option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-t <replaceable class="parameter">type</replaceable></option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-W <replaceable class="parameter">wait</replaceable></option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-m <replaceable class="parameter">flag</replaceable></option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-4</option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-6</option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-v</option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <arg choice="opt" rep="norepeat"><option>-V</option></arg>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </cmdsynopsis>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </refsynopsisdiv>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <refsection><info><title>DESCRIPTION</title></info>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk is a simple utility for performing DNS lookups.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk It is normally used to convert names to IP addresses and vice versa.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk When no arguments or options are given,
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk prints a short summary of its command line arguments and options.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <para><parameter>name</parameter> is the domain name that is to be
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk up. It can also be a dotted-decimal IPv4 address or a colon-delimited
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk IPv6 address, in which case <command>host</command> will by
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk perform a reverse lookup for that address.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <parameter>server</parameter> is an optional argument which
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk the name or IP address of the name server that <command>host</command>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk should query instead of the server or servers listed in
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The <option>-a</option> (all) option is equivalent to setting the
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <option>-v</option> option and asking <command>host</command> to make
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk a query of type ANY.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk When the <option>-C</option> option is used, <command>host</command>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk will attempt to display the SOA records for zone
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk authoritative name
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk servers for that zone. The list of name servers is defined by the NS
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk records that are found for the zone.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The <option>-c</option> option instructs to make a DNS query of class
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <parameter>class</parameter>. This can be used to lookup
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk Chaosnet class resource records. The default class is IN (Internet).
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk Verbose output is generated by <command>host</command> when
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <option>-d</option> or <option>-v</option> option is used. The two
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk options are equivalent. They have been provided for backwards
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk compatibility. In previous versions, the <option>-d</option> option
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk switched on debugging traces and <option>-v</option> enabled verbose
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk output. Verbose output can also be enabled by setting the
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk List mode is selected by the <option>-l</option> option. This makes
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <command>host</command> perform a zone transfer for zone
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <parameter>name</parameter>. Transfer the zone printing out
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk and address records (A/AAAA). If combined with <option>-a</option>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk all records will be printed.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk option specifies that reverse lookups of IPv6 addresses should
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk use the IP6.INT domain as defined in RFC1886.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The default is to use IP6.ARPA.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The <option>-N</option> option sets the number of dots that have to be
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk in <parameter>name</parameter> for it to be considered
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk absolute. The
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk default value is that defined using the ndots statement in
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <filename>/etc/resolv.conf</filename>, or 1 if no ndots
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk statement is
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk present. Names with fewer dots are interpreted as relative names and
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk will be searched for in the domains listed in the <type>search</type>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The number of UDP retries for a lookup can be changed with the
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <option>-R</option> option. <parameter>number</parameter>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk how many times <command>host</command> will repeat a query
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk not get answered. If
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <parameter>number</parameter> is negative or zero, the
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk retries will default to 1. The default value is 1, or
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk the value of the <parameter>attempts</parameter> option in
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk Non-recursive queries can be made via the <option>-r</option> option.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk Setting this option clears the <type>RD</type> — recursion
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk desired — bit in the query which <command>host</command> makes.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk This should mean that the name server receiving the query will not
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk attempt to resolve <parameter>name</parameter>. The
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <option>-r</option> option enables <command>host</command>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk the behavior of a name server by making non-recursive queries and
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk expecting to receive answers to those queries that are usually
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk referrals to other name servers.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk By default, <command>host</command> uses UDP when making
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk queries. The
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <option>-T</option> option makes it use a TCP connection when querying
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk the name server. TCP will be automatically selected for queries that
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk require it, such as zone transfer (AXFR) requests.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The <option>-4</option> option forces <command>host</command> to only
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk use IPv4 query transport. The <option>-6</option> option forces
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <command>host</command> to only use IPv6 query transport.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The <option>-t</option> option is used to select the query type.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <parameter>type</parameter> can be any recognized query
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk type: CNAME,
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <command>host</command> automatically selects an appropriate
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk type. By default, it looks for A, AAAA, and MX records, but if the
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <option>-C</option> option was given, queries will be made for SOA
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk records, and if <parameter>name</parameter> is a
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk dotted-decimal IPv4
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk address or colon-delimited IPv6 address, <command>host</command> will
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk query for PTR records. If a query type of IXFR is chosen the starting
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk serial number can be specified by appending an equal followed by the
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk starting serial number (e.g. -t IXFR=12345678).
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The time to wait for a reply can be controlled through the
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <option>-W</option> and <option>-w</option> options. The
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <option>-W</option> option makes <command>host</command>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <parameter>wait</parameter> seconds. If <parameter>wait</parameter>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk is less than one, the wait interval is set to one second. When the
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <option>-w</option> option is used, <command>host</command>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk effectively wait forever for a reply. The time to wait for a response
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk will be set to the number of seconds given by the hardware's maximum
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk value for an integer quantity. By default, <command>host</command>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk will wait for 5 seconds for UDP responses and 10 seconds for TCP
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk connections. These defaults can be overridden by the
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The <option>-s</option> option tells <command>host</command>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <emphasis>not</emphasis> to send the query to the next nameserver
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk if any server responds with a SERVFAIL response, which is the
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk reverse of normal stub resolver behavior.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The <option>-m</option> can be used to set the memory usage debugging
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <parameter>record</parameter>, <parameter>usage</parameter> and
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The <option>-V</option> option causes <command>host</command>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk to print the version number and exit.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </refsection>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <refsection><info><title>IDN SUPPORT</title></info>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk If <command>host</command> has been built with IDN (internationalized
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk domain name) support, it can accept and display non-ASCII domain names.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <command>host</command> appropriately converts character encoding of
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk domain name before sending a request to DNS server or displaying a
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk reply from the server.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk If you'd like to turn off the IDN support for some reason, defines
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk the <envar>IDN_DISABLE</envar> environment variable.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk The IDN support is disabled if the variable is set when
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </refsection>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </refsection>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <refsection><info><title>SEE ALSO</title></info>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <refentrytitle>dig</refentrytitle><manvolnum>1</manvolnum>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </citerefentry>,
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <citerefentry>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk <refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </citerefentry>.
5543ca2fb9cca478984a31170fc19fc01592bfd7jeff.schenk </refsection>