recursion and forward zones

[Mark Andrews]

>  
> > What do you think "recursion" means, in that context? It 
> > means your BIND 
> > instance is able and willing to go out and fetch DNS information from 
> > other nameservers, in order to satisfy client requests. The fact that 
> > you're trying to set up a forwarding zone, implies that you want to 
> > enable resolution of names in that part of the namespace 
> > hierarchy, at 
> > least for some select group of clients that ask for it. This 
> > is directly 
> > contradictory to "recursion no", which basically means "I'm 
> > only going 
> > to answer from my own authoritative data and not ask anyone 
> > else for the 
> > answers to your questions".
> > 
> > You should probably set up that forwarding zone under a 
> > separate view, 
> > one which has recursive service enabled.
> > 
> > 
> 
> I guess I though recursion would only apply to zones
> that were not all declared anywhere.
> 
> I figured if I explicitly declared a zone as forwarding
> or a slave, that that would override the recursion.
> 
> I was wrong. 
> 
> Thanks
> 
> 
	The description of forwarding from the ARM.

       <sect3>
          <title>Forwarding</title>
 
          <para>
            Even a caching name server does not necessarily perform
            the complete recursive lookup itself.  Instead, it can
            <emphasis>forward</emphasis> some or all of the queries
            that it cannot satisfy from its cache to another caching name
            server,
            commonly referred to as a <emphasis>forwarder</emphasis>.
          </para>

          <para>
            There may be one or more forwarders,
            and they are queried in turn until the list is exhausted or an
            answer
            is found. Forwarders are typically used when you do not
            wish all the servers at a given site to interact directly with the
            rest of
            the Internet servers. A typical scenario would involve a number
            of internal <acronym>DNS</acronym> servers and an
            Internet firewall. Servers unable
            to pass packets through the firewall would forward to the server
            that can do it, and that server would query the Internet <acronym>DNS
</acronym> servers
            on the internal server's behalf.
          </para>
        </sect3>



	Also 



        <sect3>
          <title>Forwarding</title>
          <para>
            The forwarding facility can be used to create a large site-wide
            cache on a few servers, reducing traffic over links to external
            name servers. It can also be used to allow queries by servers that
            do not have direct access to the Internet, but wish to look up
            exterior
            names anyway. Forwarding occurs only on those queries for which
            the server is not authoritative and does not have the answer in
            its cache.
          </para>

          <variablelist>
            <varlistentry>
              <term><command>forward</command></term>
              <listitem>
                <para>
                  This option is only meaningful if the
                  forwarders list is not empty. A value of <varname>first</varnam
e>,
                  the default, causes the server to query the forwarders
                  first, and
                  if that doesn't answer the question the server will then
                  look for
                  the answer itself. If <varname>only</varname> is
                  specified, the
                  server will only query the forwarders.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><command>forwarders</command></term>
              <listitem>
                <para>
                  Specifies the IP addresses to be used
                  for forwarding. The default is the empty list (no
                  forwarding).
                </para>
              </listitem>
            </varlistentry>

          </variablelist>

          <para>
            Forwarding can also be configured on a per-domain basis, allowing
            for the global forwarding options to be overridden in a variety
            of ways. You can set particular domains to use different
            forwarders,
            or have a different <command>forward only/first</command> behavior,
            or not forward at all, see <xref linkend="zone_statement_grammar"/>.
          </para>
        </sect3>

--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org