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8886caf5dc3db70638022ddfd5442c0930bd43b5Mark Andrews - Copyright (C) 2004-2014 Internet Systems Consortium, Inc. ("ISC")
8886caf5dc3db70638022ddfd5442c0930bd43b5Mark Andrews - Copyright (C) 2000-2003 Internet Software Consortium.
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8886caf5dc3db70638022ddfd5442c0930bd43b5Mark Andrews - purpose with or without fee is hereby granted, provided that the above
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8886caf5dc3db70638022ddfd5442c0930bd43b5Mark Andrews - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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8886caf5dc3db70638022ddfd5442c0930bd43b5Mark Andrews<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>
8886caf5dc3db70638022ddfd5442c0930bd43b5Mark Andrews<p><span><strong class="command">host</strong></span>
8886caf5dc3db70638022ddfd5442c0930bd43b5Mark Andrews is a simple utility for performing DNS lookups.
d39690e5a9b4a9a084d984abd193bed4395db41aDavid Lawrence It is normally used to convert names to IP addresses and vice versa.
d39690e5a9b4a9a084d984abd193bed4395db41aDavid Lawrence When no arguments or options are given,
105f5a65b1f680f4cb6f897b8b0f7ee7e09e41ebDavid Lawrence <span><strong class="command">host</strong></span>
8886caf5dc3db70638022ddfd5442c0930bd43b5Mark Andrews prints a short summary of its command line arguments and options.
88b3bc12b5570aae77e5963204e9111a2875915eAndreas Gustafsson<p><em class="parameter"><code>name</code></em> is the domain name that is to be
8886caf5dc3db70638022ddfd5442c0930bd43b5Mark Andrews up. It can also be a dotted-decimal IPv4 address or a colon-delimited
8886caf5dc3db70638022ddfd5442c0930bd43b5Mark Andrews IPv6 address, in which case <span><strong class="command">host</strong></span> will by
ff8fd4d1b6abb0490b5aaf2b1d86555750ae0818Mark Andrews perform a reverse lookup for that address.
1c9200af084f2b6f1d28eccf91525676c158cfa3Mark Andrews <em class="parameter"><code>server</code></em> is an optional argument which
9463feb3cb002df10b053f71e21540607c7a48e8Tatuya JINMEI 神明達哉 the name or IP address of the name server that <span><strong class="command">host</strong></span>
c05a979fda35c83d7fba16fee7859644e98a7450Mark Andrews should query instead of the server or servers listed in
2a313f56e78e19ae6dc2315bb53bd32fad13ae29Mark Andrews <code class="filename">/etc/resolv.conf</code>.
60c2c8814f838f503333da5b2fd7e6792ca39c14Mark Andrews The <code class="option">-a</code> (all) option is equivalent to setting the
c58088e3a0fd9e553db750cd4b08d3e621d0ded4Mark Andrews <code class="option">-v</code> option and asking <span><strong class="command">host</strong></span> to make
b9858c2efcee324745a1b8d7b099baf540bc695bMark Andrews a query of type ANY.
5a020bc04be73df06735da0ec1abb1dd71c755e5Mark Andrews When the <code class="option">-C</code> option is used, <span><strong class="command">host</strong></span>
5a020bc04be73df06735da0ec1abb1dd71c755e5Mark Andrews will attempt to display the SOA records for zone
58e0b35a3bbb50d154c36749096f7463dab75a7aMark Andrews <em class="parameter"><code>name</code></em> from all the listed
a69a77ddfef58e93036cf6173dc7f91ed864d103Mark Andrews authoritative name
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews servers for that zone. The list of name servers is defined by the NS
f4545143206d918a7f6ee53cd4fb9788c534c0c7Mark Andrews records that are found for the zone.
7ecbfb6c0f566894fb7050e021cded6822771789Mark Andrews The <code class="option">-c</code> option instructs to make a DNS query of class
ea37c1a7780311cc7076ff54f09774b2296aebe5Mark Andrews <em class="parameter"><code>class</code></em>. This can be used to lookup
49aa1303a7cf1ec2a06cde11e46a039dddfca8feMark Andrews Chaosnet class resource records. The default class is IN (Internet).
7ecbfb6c0f566894fb7050e021cded6822771789Mark Andrews Verbose output is generated by <span><strong class="command">host</strong></span> when
d4ae7d9200ebad7700e8e85886cabe93ab24afd8Mark Andrews <code class="option">-d</code> or <code class="option">-v</code> option is used. The two
f7e3edb15a73e285f34147b0092c63546c5dfbeaMark Andrews options are equivalent. They have been provided for backwards
b6f837397dadf6b296ee1825c95e90235ee5b5ffMark Andrews compatibility. In previous versions, the <code class="option">-d</code> option
7ecbfb6c0f566894fb7050e021cded6822771789Mark Andrews switched on debugging traces and <code class="option">-v</code> enabled verbose
d4cefad19e32879e6847df043e62ad8f9cbfa06bMark Andrews output. Verbose output can also be enabled by setting the
2984f8f7bf213642e47affe710851ff0d6580083Mark Andrews <em class="parameter"><code>debug</code></em> option in
666bae3ccc9d50d840dd6b7b13731f7653f74e77Mark Andrews <code class="filename">/etc/resolv.conf</code>.
fd6574dbc551faac89ae2ce6f3549fed51c24e49Mark Andrews List mode is selected by the <code class="option">-l</code> option. This makes
fd6574dbc551faac89ae2ce6f3549fed51c24e49Mark Andrews <span><strong class="command">host</strong></span> perform a zone transfer for zone
cb6fe566ff051ade7b99f5ca9fca897193d1bd4fMark Andrews <em class="parameter"><code>name</code></em>. Transfer the zone printing out
245bce4ef1e9b3e7e802141dba7c2ca878e4768bMark Andrews and address records (A/AAAA). If combined with <code class="option">-a</code>
00b872e4f76587584a2359e9001e9cf08b195ccfMark Andrews all records will be printed.
85f5fe1a722626b33eb9a490def709d02a35e65dMark Andrews option specifies that reverse lookups of IPv6 addresses should
b26014a1945864a54464b413279faad7dad6d772Mark Andrews use the IP6.INT domain as defined in RFC1886.
886fff19f145c93c64967a87e1ff5a9ce18503a6Mark Andrews The default is to use IP6.ARPA.
2b59366035cf1add576318ab336e6b4bdf170e0fMark Andrews The <code class="option">-N</code> option sets the number of dots that have to be
f7e3edb15a73e285f34147b0092c63546c5dfbeaMark Andrews in <em class="parameter"><code>name</code></em> for it to be considered
fad04ffe23de26d42bae77b69a983bd964a01883Mark Andrews absolute. The
8a655e59bc1db9927b3b418f5064ae58347b11eaMark Andrews default value is that defined using the ndots statement in
cdd28dc017ce03d208cdfbe7d55fb76377c85accMark Andrews <code class="filename">/etc/resolv.conf</code>, or 1 if no ndots
10f35749cf81005668548374a378b7c8ac2a350cMark Andrews statement is
c1c9e72292db84ebf69093f38a2d1a4a60aeebabMark Andrews present. Names with fewer dots are interpreted as relative names and
209b1d150ce0b5d8963b1ba39664e80256929011Mark Andrews will be searched for in the domains listed in the <span class="type">search</span>
fad04ffe23de26d42bae77b69a983bd964a01883Mark Andrews or <span class="type">domain</span> directive in
7ecbfb6c0f566894fb7050e021cded6822771789Mark Andrews <code class="filename">/etc/resolv.conf</code>.
f7e3edb15a73e285f34147b0092c63546c5dfbeaMark Andrews The number of UDP retries for a lookup can be changed with the
f7e3edb15a73e285f34147b0092c63546c5dfbeaMark Andrews <code class="option">-R</code> option. <em class="parameter"><code>number</code></em>
d90f3a24c725704732b106380cfc2f3dab88bb3eMark Andrews how many times <span><strong class="command">host</strong></span> will repeat a query
eccf8cc404a04ffc465a6947ed4351703dfbadafEvan Hunt not get answered. If
f7e3edb15a73e285f34147b0092c63546c5dfbeaMark Andrews <em class="parameter"><code>number</code></em> is negative or zero, the
1e18f761a7f406c5c472ddefea9513c80a67efacMark Andrews retries will default to 1. The default value is 1, or
f7e3edb15a73e285f34147b0092c63546c5dfbeaMark Andrews the value of the <em class="parameter"><code>attempts</code></em> option in
4c53f98dbda8fc3e2093a6d685f5701e908573fbMark Andrews <code class="filename">/etc/resolv.conf</code>, if set.
b24b6ddab719d78f1494fea3075cf44200fa827eMark Andrews Non-recursive queries can be made via the <code class="option">-r</code> option.
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews Setting this option clears the <span class="type">RD</span> — recursion
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews desired — bit in the query which <span><strong class="command">host</strong></span> makes.
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews This should mean that the name server receiving the query will not
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews attempt to resolve <em class="parameter"><code>name</code></em>. The
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews <code class="option">-r</code> option enables <span><strong class="command">host</strong></span>
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews the behavior of a name server by making non-recursive queries and
9b97400166683a5b80bb28e95425237261af1e0fMark Andrews expecting to receive answers to those queries that are usually
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews referrals to other name servers.
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews By default, <span><strong class="command">host</strong></span> uses UDP when making
f1c1aab2c9e720399d66d8db5f40515d47c45ecfMark Andrews queries. The
f1c1aab2c9e720399d66d8db5f40515d47c45ecfMark Andrews <code class="option">-T</code> option makes it use a TCP connection when querying
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews the name server. TCP will be automatically selected for queries that
362a13ce42fcebc41a092d8da4642d360e85eb12Mark Andrews require it, such as zone transfer (AXFR) requests.
bc98d5a4c6601bb72cd9cde7926e896b23382e26Mark Andrews The <code class="option">-4</code> option forces <span><strong class="command">host</strong></span> to only
8f20f6c9d7ce5a0f0af6ee4c5361832d97b1c5d4Mark Andrews use IPv4 query transport. The <code class="option">-6</code> option forces
f6e45a5c54b7af4b1c303e8d3ff3b7d78622df9eMark Andrews <span><strong class="command">host</strong></span> to only use IPv6 query transport.
bf8d171a66c201f8cbf23e2ee6db58ae0eb0316aMark Andrews The <code class="option">-t</code> option is used to select the query type.
bf4fe7ca1b9c313200aaefec18ac165ce9efc16bMark Andrews <em class="parameter"><code>type</code></em> can be any recognized query
44fa2773671d0782956a928ccd60ad3bb0ad08daMark Andrews type: CNAME,
e3db607c92cd958a6bd8410f93dcc7e104ed0143Tinderbox User NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
starting serial number (e.g. -t IXFR=12345678).