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06ba4a61654b3763ad65f52283832ebf058fdf1cslive<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>] {name} [server]</p></div>
06ba4a61654b3763ad65f52283832ebf058fdf1cslive is a simple utility for performing DNS lookups.
97a9a944b5887e91042b019776c41d5dd74557aferikabele It is normally used to convert names to IP addresses and vice versa.
06ba4a61654b3763ad65f52283832ebf058fdf1cslive When no arguments or options are given,
b686b6a420bde7f78c416b90be11db94cb789979nd prints a short summary of its command line arguments and options.
b686b6a420bde7f78c416b90be11db94cb789979nd<p><em class="parameter"><code>name</code></em> is the domain name that is to be
117c1f888a14e73cdd821dc6c23eb0411144a41cnd up. It can also be a dotted-decimal IPv4 address or a colon-delimited
b686b6a420bde7f78c416b90be11db94cb789979nd IPv6 address, in which case <span><strong class="command">host</strong></span> will by
b686b6a420bde7f78c416b90be11db94cb789979nd perform a reverse lookup for that address.
b686b6a420bde7f78c416b90be11db94cb789979nd <em class="parameter"><code>server</code></em> is an optional argument which
b686b6a420bde7f78c416b90be11db94cb789979nd the name or IP address of the name server that <span><strong class="command">host</strong></span>
b686b6a420bde7f78c416b90be11db94cb789979nd should query instead of the server or servers listed in
b686b6a420bde7f78c416b90be11db94cb789979nd The <code class="option">-a</code> (all) option is equivalent to setting the
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <code class="option">-v</code> option and asking <span><strong class="command">host</strong></span> to make
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd a query of type ANY.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd When the <code class="option">-C</code> option is used, <span><strong class="command">host</strong></span>
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd will attempt to display the SOA records for zone
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <em class="parameter"><code>name</code></em> from all the listed
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd authoritative name
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd servers for that zone. The list of name servers is defined by the NS
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd records that are found for the zone.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd The <code class="option">-c</code> option instructs to make a DNS query of class
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <em class="parameter"><code>class</code></em>. This can be used to lookup
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd Chaosnet class resource records. The default class is IN (Internet).
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd Verbose output is generated by <span><strong class="command">host</strong></span> when
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <code class="option">-d</code> or <code class="option">-v</code> option is used. The two
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd options are equivalent. They have been provided for backwards
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd compatibility. In previous versions, the <code class="option">-d</code> option
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd switched on debugging traces and <code class="option">-v</code> enabled verbose
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd List mode is selected by the <code class="option">-l</code> option. This makes
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <span><strong class="command">host</strong></span> perform a zone transfer for zone
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <em class="parameter"><code>name</code></em>. Transfer the zone printing out
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd the NS, PTR
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd and address records (A/AAAA). If combined with <code class="option">-a</code>
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd all records will be printed.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd option specifies that reverse lookups of IPv6 addresses should
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd use the IP6.INT domain as defined in RFC1886.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd The default is to use IP6.ARPA.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd The <code class="option">-N</code> option sets the number of dots that have to be
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd in <em class="parameter"><code>name</code></em> for it to be considered
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd absolute. The
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd default value is that defined using the ndots statement in
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <code class="filename">/etc/resolv.conf</code>, or 1 if no ndots
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd statement is
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd present. Names with fewer dots are interpreted as relative names and
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd will be searched for in the domains listed in the <span class="type">search</span>
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd The number of UDP retries for a lookup can be changed with the
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <code class="option">-R</code> option. <em class="parameter"><code>number</code></em>
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd how many times <span><strong class="command">host</strong></span> will repeat a query
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd not get answered. The default number of retries is 1. If
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <em class="parameter"><code>number</code></em> is negative or zero, the
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd retries will default to 1.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd Non-recursive queries can be made via the <code class="option">-r</code> option.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd Setting this option clears the <span class="type">RD</span> — recursion
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd desired — bit in the query which <span><strong class="command">host</strong></span> makes.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd This should mean that the name server receiving the query will not
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd attempt to resolve <em class="parameter"><code>name</code></em>. The
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <code class="option">-r</code> option enables <span><strong class="command">host</strong></span>
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd the behavior of a name server by making non-recursive queries and
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd expecting to receive answers to those queries that are usually
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd referrals to other name servers.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd By default, <span><strong class="command">host</strong></span> uses UDP when making
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd queries. The
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <code class="option">-T</code> option makes it use a TCP connection when querying
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd the name server. TCP will be automatically selected for queries that
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd require it, such as zone transfer (AXFR) requests.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd The <code class="option">-4</code> option forces <span><strong class="command">host</strong></span> to only
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd use IPv4 query transport. The <code class="option">-6</code> option forces
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <span><strong class="command">host</strong></span> to only use IPv6 query transport.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd The <code class="option">-t</code> option is used to select the query type.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <em class="parameter"><code>type</code></em> can be any recognized query
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd type: CNAME,
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <span><strong class="command">host</strong></span> automatically selects an appropriate
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd type. By default, it looks for A, AAAA, and MX records, but if the
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <code class="option">-C</code> option was given, queries will be made for SOA
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd records, and if <em class="parameter"><code>name</code></em> is a
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd dotted-decimal IPv4
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd address or colon-delimited IPv6 address, <span><strong class="command">host</strong></span> will
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd query for PTR records. If a query type of IXFR is chosen the starting
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd serial number can be specified by appending an equal followed by the
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd starting serial number (e.g. -t IXFR=12345678).
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd The time to wait for a reply can be controlled through the
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <code class="option">-W</code> and <code class="option">-w</code> options. The
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <code class="option">-W</code> option makes <span><strong class="command">host</strong></span>
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <em class="parameter"><code>wait</code></em> seconds. If <em class="parameter"><code>wait</code></em>
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd is less than one, the wait interval is set to one second. When the
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <code class="option">-w</code> option is used, <span><strong class="command">host</strong></span>
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd effectively wait forever for a reply. The time to wait for a response
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd will be set to the number of seconds given by the hardware's maximum
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd value for an integer quantity.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd The <code class="option">-s</code> option tells <span><strong class="command">host</strong></span>
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <span class="emphasis"><em>not</em></span> to send the query to the next nameserver
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd if any server responds with a SERVFAIL response, which is the
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd reverse of normal stub resolver behavior.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd The <code class="option">-m</code> can be used to set the memory usage debugging
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <em class="parameter"><code>record</code></em>, <em class="parameter"><code>usage</code></em> and
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd If <span><strong class="command">host</strong></span> has been built with IDN (internationalized
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd domain name) support, it can accept and display non-ASCII domain names.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd <span><strong class="command">host</strong></span> appropriately converts character encoding of
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd domain name before sending a request to DNS server or displaying a
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd reply from the server.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd If you'd like to turn off the IDN support for some reason, defines
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd the <code class="envar">IDN_DISABLE</code> environment variable.
75585bd48fe0f30483dba4762e61edf39ea3e0f6nd The IDN support is disabled if the variable is set when
b686b6a420bde7f78c416b90be11db94cb789979nd<p><span class="citerefentry"><span class="refentrytitle">dig</span>(1)</span>,
b686b6a420bde7f78c416b90be11db94cb789979nd <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>.
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