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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="man.nslookup">
<info>
<date>2014-01-24</date>
</info>
<refentryinfo>
<corpname>ISC</corpname>
<corpauthor>Internet Systems Consortium, Inc.</corpauthor>
</refentryinfo>
<refmeta>
<refentrytitle>nslookup</refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo>BIND9</refmiscinfo>
</refmeta>
<refnamediv>
<refname>nslookup</refname>
<refpurpose>query Internet name servers interactively</refpurpose>
</refnamediv>
<docinfo>
<copyright>
<year>2004</year>
<year>2005</year>
<year>2006</year>
<year>2007</year>
<year>2010</year>
<year>2013</year>
<year>2014</year>
<year>2015</year>
<year>2016</year>
<year>2017</year>
<year>2018</year>
<year>2019</year>
<year>2020</year>
<holder>Internet Systems Consortium, Inc. ("ISC")</holder>
</copyright>
</docinfo>
<refsynopsisdiv>
<cmdsynopsis sepchar=" ">
<command>nslookup</command>
<arg choice="opt" rep="norepeat"><option>-option</option></arg>
<arg choice="opt" rep="norepeat">name | -</arg>
<arg choice="opt" rep="norepeat">server</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsection><info><title>DESCRIPTION</title></info>
<para><command>Nslookup</command>
is a program to query Internet domain name servers. <command>Nslookup</command>
has two modes: interactive and non-interactive. Interactive mode allows
the user to query name servers for information about various hosts and
domains or to print a list of hosts in a domain. Non-interactive mode
is
used to print just the name and requested information for a host or
domain.
</para>
</refsection>
<refsection><info><title>ARGUMENTS</title></info>
<para>
Interactive mode is entered in the following cases:
<orderedlist numeration="loweralpha" inheritnum="ignore" continuation="restarts">
<listitem>
<para>
when no arguments are given (the default name server will be used)
</para>
</listitem>
<listitem>
<para>
when the first argument is a hyphen (-) and the second argument is
the host name or Internet address of a name server.
</para>
</listitem>
</orderedlist>
</para>
<para>
Non-interactive mode is used when the name or Internet address of the
host to be looked up is given as the first argument. The optional second
argument specifies the host name or address of a name server.
</para>
<para>
Options can also be specified on the command line if they precede the
arguments and are prefixed with a hyphen. For example, to
change the default query type to host information, and the initial
timeout to 10 seconds, type:
<!-- <informalexample> produces bad nroff. -->
<programlisting>
nslookup -query=hinfo -timeout=10
</programlisting>
<!-- </informalexample> -->
</para>
<para>
The <option>-version</option> option causes
<command>nslookup</command> to print the version
number and immediately exits.
</para>
</refsection>
<refsection><info><title>INTERACTIVE COMMANDS</title></info>
<variablelist>
<varlistentry>
<term><constant>host</constant> <optional>server</optional></term>
<listitem>
<para>
Look up information for host using the current default server or
using server, if specified. If host is an Internet address and
the query type is A or PTR, the name of the host is returned.
If host is a name and does not have a trailing period, the
search list is used to qualify the name.
</para>
<para>
To look up a host not in the current domain, append a period to
the name.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>server</constant> <replaceable class="parameter">domain</replaceable></term>
<listitem>
<para/>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>lserver</constant> <replaceable class="parameter">domain</replaceable></term>
<listitem>
<para>
Change the default server to <replaceable>domain</replaceable>; <constant>lserver</constant> uses the initial
server to look up information about <replaceable>domain</replaceable>, while <constant>server</constant> uses
the current default server. If an authoritative answer can't be
found, the names of servers that might have the answer are
returned.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>root</constant></term>
<listitem>
<para>
not implemented
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>finger</constant></term>
<listitem>
<para>
not implemented
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>ls</constant></term>
<listitem>
<para>
not implemented
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>view</constant></term>
<listitem>
<para>
not implemented
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>help</constant></term>
<listitem>
<para>
not implemented
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>?</constant></term>
<listitem>
<para>
not implemented
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>exit</constant></term>
<listitem>
<para>
Exits the program.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>set</constant>
<replaceable>keyword<optional>=value</optional></replaceable></term>
<listitem>
<para>
This command is used to change state information that affects
the lookups. Valid keywords are:
<variablelist>
<varlistentry>
<term><constant>all</constant></term>
<listitem>
<para>
Prints the current values of the frequently used
options to <command>set</command>.
Information about the current default
server and host is also printed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>class=</constant><replaceable>value</replaceable></term>
<listitem>
<para>
Change the query class to one of:
<variablelist>
<varlistentry>
<term><constant>IN</constant></term>
<listitem>
<para>
the Internet class
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>CH</constant></term>
<listitem>
<para>
the Chaos class
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>HS</constant></term>
<listitem>
<para>
the Hesiod class
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>ANY</constant></term>
<listitem>
<para>
wildcard
</para>
</listitem>
</varlistentry>
</variablelist>
The class specifies the protocol group of the information.
</para>
<para>
(Default = IN; abbreviation = cl)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant><replaceable><optional>no</optional></replaceable>debug</constant></term>
<listitem>
<para>
Turn on or off the display of the full response packet and
any intermediate response packets when searching.
</para>
<para>
(Default = nodebug; abbreviation = <optional>no</optional>deb)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant><replaceable><optional>no</optional></replaceable>d2</constant></term>
<listitem>
<para>
Turn debugging mode on or off. This displays more about
what nslookup is doing.
</para>
<para>
(Default = nod2)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>domain=</constant><replaceable>name</replaceable></term>
<listitem>
<para>
Sets the search list to <replaceable>name</replaceable>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant><replaceable><optional>no</optional></replaceable>search</constant></term>
<listitem>
<para>
If the lookup request contains at least one period but
doesn't end with a trailing period, append the domain
names in the domain search list to the request until an
answer is received.
</para>
<para>
(Default = search)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>port=</constant><replaceable>value</replaceable></term>
<listitem>
<para>
Change the default TCP/UDP name server port to <replaceable>value</replaceable>.
</para>
<para>
(Default = 53; abbreviation = po)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>querytype=</constant><replaceable>value</replaceable></term>
<listitem>
<para/>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>type=</constant><replaceable>value</replaceable></term>
<listitem>
<para>
Change the type of the information query.
</para>
<para>
(Default = A and then AAAA; abbreviations = q, ty)
</para>
<para>
<emphasis role="bold">Note:</emphasis> It is
only possible to specify one query type, only
the default behavior looks up both when an
alternative is not specified.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant><replaceable><optional>no</optional></replaceable>recurse</constant></term>
<listitem>
<para>
Tell the name server to query other servers if it does not
have the
information.
</para>
<para>
(Default = recurse; abbreviation = [no]rec)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>ndots=</constant><replaceable>number</replaceable></term>
<listitem>
<para>
Set the number of dots (label separators) in a domain
that will disable searching. Absolute names always
stop searching.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>retry=</constant><replaceable>number</replaceable></term>
<listitem>
<para>
Set the number of retries to number.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>timeout=</constant><replaceable>number</replaceable></term>
<listitem>
<para>
Change the initial timeout interval for waiting for a
reply to number seconds.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant><replaceable><optional>no</optional></replaceable>vc</constant></term>
<listitem>
<para>
Always use a virtual circuit when sending requests to the
server.
</para>
<para>
(Default = novc)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant><replaceable><optional>no</optional></replaceable>fail</constant></term>
<listitem>
<para>
Try the next nameserver if a nameserver responds with
SERVFAIL or a referral (nofail) or terminate query
(fail) on such a response.
</para>
<para>
(Default = nofail)
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
</variablelist>
</refsection>
<refsection><info><title>RETURN VALUES</title></info>
<para>
<command>nslookup</command> returns with an exit status of 1
if any query failed, and 0 otherwise.
</para>
</refsection>
<refsection><info><title>IDN SUPPORT</title></info>
<para>
If <command>nslookup</command> has been built with IDN (internationalized
domain name) support, it can accept and display non-ASCII domain names.
<command>nslookup</command> appropriately converts character encoding of
domain name before sending a request to DNS server or displaying a
reply from the server.
If you'd like to turn off the IDN support for some reason, define
the <envar>IDN_DISABLE</envar> environment variable.
The IDN support is disabled if the variable is set when
<command>nslookup</command> runs or when the standard output is not
a tty.
</para>
</refsection>
<refsection><info><title>FILES</title></info>
<para><filename>/etc/resolv.conf</filename>
</para>
</refsection>
<refsection><info><title>SEE ALSO</title></info>
<para><citerefentry>
<refentrytitle>dig</refentrytitle><manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>host</refentrytitle><manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>.
</para>
</refsection>
</refentry>