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<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0" xml:id="man.named">
  <info>
    <date>2014-02-19</date>
  </info>
  <refentryinfo>
    <corpname>ISC</corpname>
    <corpauthor>Internet Systems Consortium, Inc.</corpauthor>
  </refentryinfo>

  <refmeta>
    <refentrytitle><application>named</application></refentrytitle>
    <manvolnum>8</manvolnum>
    <refmiscinfo>BIND9</refmiscinfo>
  </refmeta>

  <refnamediv>
    <refname><application>named</application></refname>
    <refpurpose>Internet domain name server</refpurpose>
  </refnamediv>

  <docinfo>
    <copyright>
      <year>2000</year>
      <year>2001</year>
      <year>2003</year>
      <year>2004</year>
      <year>2005</year>
      <year>2006</year>
      <year>2007</year>
      <year>2008</year>
      <year>2009</year>
      <year>2011</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>named</command>
      <group choice="opt" rep="norepeat">
	<arg choice="opt" rep="norepeat"><option>-4</option></arg>
	<arg choice="opt" rep="norepeat"><option>-6</option></arg>
      </group>
      <arg choice="opt" rep="norepeat"><option>-c <replaceable class="parameter">config-file</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-d <replaceable class="parameter">debug-level</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-D <replaceable class="parameter">string</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-E <replaceable class="parameter">engine-name</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-f</option></arg>
      <arg choice="opt" rep="norepeat"><option>-g</option></arg>
      <arg choice="opt" rep="norepeat"><option>-L <replaceable class="parameter">logfile</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-M <replaceable class="parameter">option</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-m <replaceable class="parameter">flag</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-n <replaceable class="parameter">#cpus</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-p <replaceable class="parameter">port</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-s</option></arg>
      <arg choice="opt" rep="norepeat"><option>-S <replaceable class="parameter">#max-socks</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-t <replaceable class="parameter">directory</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-U <replaceable class="parameter">#listeners</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-u <replaceable class="parameter">user</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-v</option></arg>
      <arg choice="opt" rep="norepeat"><option>-V</option></arg>
      <arg choice="opt" rep="norepeat"><option>-X <replaceable class="parameter">lock-file</replaceable></option></arg>
      <arg choice="opt" rep="norepeat"><option>-x <replaceable class="parameter">cache-file</replaceable></option></arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsection><info><title>DESCRIPTION</title></info>

    <para><command>named</command>
      is a Domain Name System (DNS) server,
      part of the BIND 9 distribution from ISC.  For more
      information on the DNS, see RFCs 1033, 1034, and 1035.
    </para>
    <para>
      When invoked without arguments, <command>named</command>
      will
      read the default configuration file
      <filename>/etc/named.conf</filename>, read any initial
      data, and listen for queries.
    </para>
  </refsection>

  <refsection><info><title>OPTIONS</title></info>


    <variablelist>
      <varlistentry>
        <term>-4</term>
        <listitem>
          <para>
            Use IPv4 only even if the host machine is capable of IPv6.
            <option>-4</option> and <option>-6</option> are mutually
            exclusive.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-6</term>
        <listitem>
          <para>
            Use IPv6 only even if the host machine is capable of IPv4.
            <option>-4</option> and <option>-6</option> are mutually
            exclusive.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-c <replaceable class="parameter">config-file</replaceable></term>
        <listitem>
          <para>
            Use <replaceable class="parameter">config-file</replaceable> as the
            configuration file instead of the default,
            <filename>/etc/named.conf</filename>.  To
            ensure that reloading the configuration file continues
            to work after the server has changed its working
            directory due to to a possible
            <option>directory</option> option in the configuration
            file, <replaceable class="parameter">config-file</replaceable> should be
            an absolute pathname.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-d <replaceable class="parameter">debug-level</replaceable></term>
        <listitem>
          <para>
            Set the daemon's debug level to <replaceable class="parameter">debug-level</replaceable>.
            Debugging traces from <command>named</command> become
            more verbose as the debug level increases.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-D <replaceable class="parameter">string</replaceable></term>
        <listitem>
          <para>
            Specifies a string that is used to identify a instance of
            <command>named</command> in a process listing.  The contents
            of <replaceable class="parameter">string</replaceable> are
            not examined.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-E <replaceable class="parameter">engine-name</replaceable></term>
        <listitem>
          <para>
            When applicable, specifies the hardware to use for
            cryptographic operations, such as a secure key store used
            for signing.
          </para>
          <para>
            When BIND is built with OpenSSL PKCS#11 support, this defaults
            to the string "pkcs11", which identifies an OpenSSL engine
            that can drive a cryptographic accelerator or hardware service
            module.  When BIND is built with native PKCS#11 cryptography
            (--enable-native-pkcs11), it defaults to the path of the PKCS#11
            provider library specified via "--with-pkcs11".
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-f</term>
        <listitem>
          <para>
            Run the server in the foreground (i.e. do not daemonize).
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-g</term>
        <listitem>
          <para>
            Run the server in the foreground and force all logging
            to <filename>stderr</filename>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-L <replaceable class="parameter">logfile</replaceable></term>
        <listitem>
          <para>
            Log to the file <option>logfile</option> by default
            instead of the system log.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-M <replaceable class="parameter">option</replaceable></term>
        <listitem>
          <para>
            Sets the default memory context options. If set to
            <replaceable class="parameter">external</replaceable>,
            this causes the internal memory manager to be bypassed
            in favor of system-provided memory allocation functions.
            If set to <replaceable class="parameter">fill</replaceable>,
            blocks of memory will be filled with tag values when allocated
            or freed, to assist debugging of memory problems.
            (<replaceable class="parameter">nofill</replaceable>
            disables this behavior, and is the default unless
            <command>named</command> has been compiled with developer
            options.)
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-m <replaceable class="parameter">flag</replaceable></term>
        <listitem>
          <para>
            Turn on memory usage debugging flags.  Possible flags are
            <replaceable class="parameter">usage</replaceable>,
            <replaceable class="parameter">trace</replaceable>,
            <replaceable class="parameter">record</replaceable>,
            <replaceable class="parameter">size</replaceable>, and
            <replaceable class="parameter">mctx</replaceable>.
            These correspond to the ISC_MEM_DEBUGXXXX flags described in
            <filename>&lt;isc/mem.h&gt;</filename>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-n <replaceable class="parameter">#cpus</replaceable></term>
        <listitem>
          <para>
            Create <replaceable class="parameter">#cpus</replaceable> worker threads
            to take advantage of multiple CPUs.  If not specified,
            <command>named</command> will try to determine the
            number of CPUs present and create one thread per CPU.
            If it is unable to determine the number of CPUs, a
            single worker thread will be created.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-p <replaceable class="parameter">port</replaceable></term>
        <listitem>
          <para>
            Listen for queries on port <replaceable class="parameter">port</replaceable>.  If not
            specified, the default is port 53.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-s</term>
        <listitem>
          <para>
            Write memory usage statistics to <filename>stdout</filename> on exit.
          </para>
          <note>
            <para>
              This option is mainly of interest to BIND 9 developers
              and may be removed or changed in a future release.
            </para>
          </note>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-S <replaceable class="parameter">#max-socks</replaceable></term>
        <listitem>
          <para>
            Allow <command>named</command> to use up to
            <replaceable class="parameter">#max-socks</replaceable> sockets.
            The default value is 21000 on systems built with default
            configuration options, and 4096 on systems built with
            "configure --with-tuning=small".
          </para>
          <warning>
            <para>
              This option should be unnecessary for the vast majority
              of users.
              The use of this option could even be harmful because the
              specified value may exceed the limitation of the
              underlying system API.
              It is therefore set only when the default configuration
              causes exhaustion of file descriptors and the
              operational environment is known to support the
              specified number of sockets.
              Note also that the actual maximum number is normally a little
              fewer than the specified value because
              <command>named</command> reserves some file descriptors
              for its internal use.
            </para>
          </warning>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-t <replaceable class="parameter">directory</replaceable></term>
        <listitem>
          <para>Chroot
            to <replaceable class="parameter">directory</replaceable> after
            processing the command line arguments, but before
            reading the configuration file.
          </para>
          <warning>
            <para>
              This option should be used in conjunction with the
              <option>-u</option> option, as chrooting a process
              running as root doesn't enhance security on most
              systems; the way <function>chroot(2)</function> is
              defined allows a process with root privileges to
              escape a chroot jail.
            </para>
          </warning>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-U <replaceable class="parameter">#listeners</replaceable></term>
        <listitem>
          <para>
            Use <replaceable class="parameter">#listeners</replaceable>
            worker threads to listen for incoming UDP packets on each
            address.  If not specified, <command>named</command> will
            calculate a default value based on the number of detected
            CPUs: 1 for 1 CPU, and the number of detected CPUs
            minus one for machines with more than 1 CPU. This cannot
            be increased to a value higher than the number of CPUs.
            If <option>-n</option> has been set to a higher value than
            the number of detected CPUs, then <option>-U</option> may
            be increased as high as that value, but no higher.
            On Windows, the number of UDP listeners is hardwired to 1
            and this option has no effect.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-u <replaceable class="parameter">user</replaceable></term>
        <listitem>
          <para>Setuid
            to <replaceable class="parameter">user</replaceable> after completing
            privileged operations, such as creating sockets that
            listen on privileged ports.
          </para>
          <note>
            <para>
              On Linux, <command>named</command> uses the kernel's
                        capability mechanism to drop all root privileges
              except the ability to <function>bind(2)</function> to
              a
              privileged port and set process resource limits.
              Unfortunately, this means that the <option>-u</option>
              option only works when <command>named</command> is
              run
              on kernel 2.2.18 or later, or kernel 2.3.99-pre3 or
              later, since previous kernels did not allow privileges
              to be retained after <function>setuid(2)</function>.
            </para>
          </note>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-v</term>
        <listitem>
          <para>
            Report the version number and exit.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-V</term>
        <listitem>
          <para>
            Report the version number and build options, and exit.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-X <replaceable class="parameter">lock-file</replaceable></term>
        <listitem>
          <para>
            Acquire a lock on the specified file at runtime; this
            helps to prevent duplicate <command>named</command> instances
            from running simultaneously.
            Use of this option overrides the <command>lock-file</command>
            option in <filename>named.conf</filename>.
            If set to <literal>none</literal>, the lock file check
            is disabled.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-x <replaceable class="parameter">cache-file</replaceable></term>
        <listitem>
          <para>
            Load data from <replaceable class="parameter">cache-file</replaceable> into the
            cache of the default view.
          </para>
          <warning>
            <para>
              This option must not be used.  It is only of interest
              to BIND 9 developers and may be removed or changed in a
              future release.
            </para>
          </warning>
        </listitem>
      </varlistentry>

    </variablelist>

  </refsection>

  <refsection><info><title>SIGNALS</title></info>

    <para>
      In routine operation, signals should not be used to control
      the nameserver; <command>rndc</command> should be used
      instead.
    </para>

    <variablelist>

      <varlistentry>
        <term>SIGHUP</term>
        <listitem>
          <para>
            Force a reload of the server.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>SIGINT, SIGTERM</term>
        <listitem>
          <para>
            Shut down the server.
          </para>
        </listitem>
      </varlistentry>

    </variablelist>

    <para>
      The result of sending any other signals to the server is undefined.
    </para>

  </refsection>

  <refsection><info><title>CONFIGURATION</title></info>

    <para>
      The <command>named</command> configuration file is too complex
      to describe in detail here.  A complete description is provided
      in the
      <citetitle>BIND 9 Administrator Reference Manual</citetitle>.
    </para>

    <para>
      <command>named</command> inherits the <function>umask</function>
      (file creation mode mask) from the parent process. If files
      created by <command>named</command>, such as journal files,
      need to have custom permissions, the <function>umask</function>
      should be set explicitly in the script used to start the
      <command>named</command> process.
    </para>

  </refsection>

  <refsection><info><title>FILES</title></info>


    <variablelist>

      <varlistentry>
        <term><filename>/etc/named.conf</filename></term>
        <listitem>
          <para>
            The default configuration file.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><filename>/var/run/named/named.pid</filename></term>
        <listitem>
          <para>
            The default process-id file.
          </para>
        </listitem>
      </varlistentry>

    </variablelist>

  </refsection>

  <refsection><info><title>SEE ALSO</title></info>

    <para><citetitle>RFC 1033</citetitle>,
      <citetitle>RFC 1034</citetitle>,
      <citetitle>RFC 1035</citetitle>,
      <citerefentry>
        <refentrytitle>named-checkconf</refentrytitle>
        <manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>named-checkzone</refentrytitle>
        <manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>rndc</refentrytitle>
        <manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>named.conf</refentrytitle>
        <manvolnum>5</manvolnum>
      </citerefentry>,
      <citetitle>BIND 9 Administrator Reference Manual</citetitle>.
    </para>
  </refsection>

</refentry>
