294N/A<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

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787N/A [<!ENTITY mdash "&#8212;">]>

873N/A

789N/A<refentry id="man.host">

789N/A

789N/A <refentryinfo>

789N/A <date>January 20, 2009</date>

789N/A </refentryinfo>

789N/A

789N/A <refmeta>

789N/A <refentrytitle>host</refentrytitle>

789N/A <manvolnum>1</manvolnum>

789N/A <refmiscinfo>BIND9</refmiscinfo>

789N/A </refmeta>

873N/A

873N/A <refnamediv>

911N/A <refname>host</refname>

911N/A <refpurpose>DNS lookup utility</refpurpose>

911N/A </refnamediv>

873N/A

873N/A <docinfo>

873N/A <copyright>

789N/A <year>2004</year>

787N/A <year>2005</year>

294N/A <year>2007</year>

294N/A <year>2008</year>

294N/A <year>2009</year>

294N/A <holder>Internet Systems Consortium, Inc. ("ISC")</holder>

294N/A </copyright>

294N/A <copyright>

294N/A <year>2000</year>

877N/A <year>2001</year>

869N/A <year>2002</year>

789N/A <holder>Internet Software Consortium.</holder>

789N/A </copyright>

911N/A </docinfo>

789N/A

789N/A <refsynopsisdiv>

868N/A <cmdsynopsis>

294N/A <command>host</command>

294N/A <arg><option>-aCdlnrsTwv</option></arg>

294N/A <arg><option>-c <replaceable class="parameter">class</replaceable></option></arg>

294N/A <arg><option>-N <replaceable class="parameter">ndots</replaceable></option></arg>

294N/A <arg><option>-R <replaceable class="parameter">number</replaceable></option></arg>

789N/A <arg><option>-t <replaceable class="parameter">type</replaceable></option></arg>

294N/A <arg><option>-W <replaceable class="parameter">wait</replaceable></option></arg>

787N/A <arg><option>-m <replaceable class="parameter">flag</replaceable></option></arg>

789N/A <arg><option>-4</option></arg>

789N/A <arg><option>-6</option></arg>

787N/A <arg choice="req">name</arg>

869N/A <arg choice="opt">server</arg>

869N/A </cmdsynopsis>

869N/A </refsynopsisdiv>

869N/A

789N/A <refsect1>

789N/A <title>DESCRIPTION</title>

789N/A

789N/A <para><command>host</command>

789N/A is a simple utility for performing DNS lookups.

789N/A It is normally used to convert names to IP addresses and vice versa.

294N/A When no arguments or options are given,

789N/A <command>host</command>

294N/A prints a short summary of its command line arguments and options.

294N/A </para>

789N/A

294N/A <para><parameter>name</parameter> is the domain name that is to be

294N/A looked

294N/A up. It can also be a dotted-decimal IPv4 address or a colon-delimited

294N/A IPv6 address, in which case <command>host</command> will by

294N/A default

294N/A perform a reverse lookup for that address.

294N/A <parameter>server</parameter> is an optional argument which

789N/A is either

789N/A the name or IP address of the name server that <command>host</command>

789N/A should query instead of the server or servers listed in

787N/A <filename>/etc/resolv.conf</filename>.

789N/A </para>

294N/A

869N/A <para>

868N/A The <option>-a</option> (all) option is equivalent to setting the

789N/A <option>-v</option> option and asking <command>host</command> to make

789N/A a query of type ANY.

869N/A </para>

869N/A

869N/A <para>

869N/A When the <option>-C</option> option is used, <command>host</command>

789N/A will attempt to display the SOA records for zone

789N/A <parameter>name</parameter> from all the listed

869N/A authoritative name

869N/A servers for that zone. The list of name servers is defined by the NS

789N/A records that are found for the zone.

789N/A </para>

869N/A

913N/A <para>

789N/A The <option>-c</option> option instructs to make a DNS query of class

787N/A <parameter>class</parameter>. This can be used to lookup

787N/A Hesiod or

294N/A Chaosnet class resource records. The default class is IN (Internet).

294N/A </para>

789N/A

294N/A <para>

294N/A Verbose output is generated by <command>host</command> when

294N/A the

294N/A <option>-d</option> or <option>-v</option> option is used. The two

789N/A options are equivalent. They have been provided for backwards

294N/A compatibility. In previous versions, the <option>-d</option> option

294N/A switched on debugging traces and <option>-v</option> enabled verbose

294N/A output.

789N/A </para>

294N/A

789N/A <para>

294N/A List mode is selected by the <option>-l</option> option. This makes

789N/A <command>host</command> perform a zone transfer for zone

789N/A <parameter>name</parameter>. Transfer the zone printing out

911N/A the NS, PTR

911N/A and address records (A/AAAA). If combined with <option>-a</option>

911N/A all records will be printed.

915N/A </para>

911N/A

911N/A <para>

911N/A The <option>-i</option>

869N/A option specifies that reverse lookups of IPv6 addresses should

869N/A use the IP6.INT domain as defined in RFC1886.

869N/A The default is to use IP6.ARPA.

869N/A </para>

789N/A

857N/A <para>

789N/A The <option>-N</option> option sets the number of dots that have to be

789N/A in <parameter>name</parameter> for it to be considered

789N/A absolute. The

789N/A default value is that defined using the ndots statement in

789N/A <filename>/etc/resolv.conf</filename>, or 1 if no ndots

294N/A statement is

294N/A present. Names with fewer dots are interpreted as relative names and

789N/A will be searched for in the domains listed in the <type>search</type>

294N/A or <type>domain</type> directive in

294N/A <filename>/etc/resolv.conf</filename>.

789N/A </para>

294N/A

294N/A <para>

294N/A The number of UDP retries for a lookup can be changed with the

789N/A <option>-R</option> option. <parameter>number</parameter>

294N/A indicates

877N/A how many times <command>host</command> will repeat a query

877N/A that does

877N/A not get answered. The default number of retries is 1. If

869N/A <parameter>number</parameter> is negative or zero, the

869N/A number of

868N/A retries will default to 1.

869N/A </para>

869N/A

869N/A <para>

868N/A Non-recursive queries can be made via the <option>-r</option> option.

789N/A Setting this option clears the <type>RD</type> &mdash; recursion

911N/A desired &mdash; bit in the query which <command>host</command> makes.

911N/A This should mean that the name server receiving the query will not

911N/A attempt to resolve <parameter>name</parameter>. The

911N/A <option>-r</option> option enables <command>host</command>

294N/A to mimic

869N/A the behavior of a name server by making non-recursive queries and

869N/A expecting to receive answers to those queries that are usually

869N/A referrals to other name servers.

873N/A </para>

872N/A

873N/A <para>

872N/A By default, <command>host</command> uses UDP when making

869N/A queries. The

869N/A <option>-T</option> option makes it use a TCP connection when querying

869N/A the name server. TCP will be automatically selected for queries that

869N/A require it, such as zone transfer (AXFR) requests.

868N/A </para>

869N/A

869N/A <para>

869N/A The <option>-4</option> option forces <command>host</command> to only

869N/A use IPv4 query transport. The <option>-6</option> option forces

868N/A <command>host</command> to only use IPv6 query transport.

870N/A </para>

870N/A

870N/A <para>

870N/A The <option>-t</option> option is used to select the query type.

870N/A <parameter>type</parameter> can be any recognized query

869N/A type: CNAME,

869N/A NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,

869N/A <command>host</command> automatically selects an appropriate

869N/A query

869N/A type. By default, it looks for A, AAAA, and MX records, but if the

869N/A <option>-C</option> option was given, queries will be made for SOA

869N/A records, and if <parameter>name</parameter> is a

912N/A dotted-decimal IPv4

912N/A address or colon-delimited IPv6 address, <command>host</command> will

868N/A query for PTR records. If a query type of IXFR is chosen the starting

789N/A serial number can be specified by appending an equal followed by the

789N/A starting serial number (e.g. -t IXFR=12345678).

789N/A </para>

789N/A

789N/A <para>

877N/A The time to wait for a reply can be controlled through the

877N/A <option>-W</option> and <option>-w</option> options. The

877N/A <option>-W</option> option makes <command>host</command>

877N/A wait for

877N/A <parameter>wait</parameter> seconds. If <parameter>wait</parameter>

787N/A is less than one, the wait interval is set to one second. When the

294N/A <option>-w</option> option is used, <command>host</command>

789N/A will

789N/A effectively wait forever for a reply. The time to wait for a response

789N/A will be set to the number of seconds given by the hardware's maximum

789N/A value for an integer quantity.

789N/A </para>

789N/A

877N/A <para>

877N/A The <option>-s</option> option tells <command>host</command>

877N/A <emphasis>not</emphasis> to send the query to the next nameserver

877N/A if any server responds with a SERVFAIL response, which is the

877N/A reverse of normal stub resolver behavior.

789N/A </para>

294N/A

869N/A <para>

869N/A The <option>-m</option> can be used to set the memory usage debugging

869N/A flags

869N/A <parameter>record</parameter>, <parameter>usage</parameter> and

869N/A <parameter>trace</parameter>.

869N/A </para>

869N/A </refsect1>

869N/A

294N/A <refsect1>

294N/A <title>IDN SUPPORT</title>

294N/A <para>

294N/A If <command>host</command> has been built with IDN (internationalized

294N/A domain name) support, it can accept and display non-ASCII domain names.

294N/A <command>host</command> appropriately converts character encoding of

294N/A domain name before sending a request to DNS server or displaying a

294N/A reply from the server.

294N/A If you'd like to turn off the IDN support for some reason, defines

294N/A the <envar>IDN_DISABLE</envar> environment variable.

869N/A The IDN support is disabled if the variable is set when

294N/A <command>host</command> runs.

294N/A </para>

869N/A </refsect1>

873N/A

873N/A <refsect1>

872N/A <title>FILES</title>

873N/A <para><filename>/etc/resolv.conf</filename>

873N/A </para>

872N/A </refsect1>

789N/A

789N/A <refsect1>

789N/A <title>SEE ALSO</title>

789N/A <para><citerefentry>

789N/A <refentrytitle>dig</refentrytitle><manvolnum>1</manvolnum>

789N/A </citerefentry>,

789N/A <citerefentry>

789N/A <refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>

789N/A </citerefentry>.

789N/A </para>

789N/A

789N/A </refsect1>

789N/A</refentry><!--

789N/A