DNS newbie question

iceman80231 at yahoo.com iceman80231 at yahoo.com
Fri May 13 13:34:43 UTC 2005


David Botham wrote:
> bind-users-bounce at isc.org wrote on 05/11/2005 12:02:09 PM:
> >
> > Chris wrote:
> > > <iceman80231 at yahoo.com> wrote in message
> > news:d5qruk$nck$1 at sf1.isc.org...
> > > > Hello everyone,
> > > >
> > > > I have two DNS servers external to my firewall, running BIND
9.2.2.
> > > > Any hostnames that they cannot resolve are being forwarded to
my
> > ISP's
> > > > DNS servers.  My servers have zone data files and I wanted to
see
> > if
> > > > caching was enabled and, if not, to configure BIND so that it
is
> > > > enabled.  After endless searching on Google, I have heard very
bad
> > > > things about nscd and BIND not working well together so I want
to
> > > > reconfigure BIND to continue to resolve hostnames with its own
zone
> > > > data files, forward requests it cannot handle to the ISP's DNS
> > servers,
> > > > AND cache the latter results to cut down on requests made to
the
> > ISP's
> > > > DNS servers.  Many thanks.
> > > >
> > > >
> > >
> > > Why use forwarders at all. You have a fully capable DNS server so
> > don't send
> > > recursive queries to your ISP's servers. Let yours do the leg
work.
> > >
> > > Chris.
> >
> > Chris, thanks for the advice.  At the same time, at least for my
> > knowledge, I am very curious about the following:
> >
> > a)The earlier respondent said that BIND caches by default.  How do
we
> > know this, i.e. is there a configuration setting/switch in which
this
> > feature is turned on/off?  If so, what is it and in what file is it
> > stored?
>
> We know this (that BIND caches by default) because we read the
> Administrators Reference Manual (ARM) that comes with BIND.  You can
get
> it at www.isc.org.  If you are interested in tuning how the cache is
> handled, search for the word "cache" in Chapter 6 of the ARM.
>
> >
> > b)Is there a way to see the cache data?  How is it stored, e.g. is
it
>
> Yes.  To see the cache use:
>
> "rndc dumpdb"
>
>
> The cache will be dumped to the file specified by the "dump-file"
option
> in named.conf (see the ARM, chapter 6).
>
> > written to a file whose contents are wiped based upon the TTL
specified
> > on the DNS server in question or is it memory-resident and wiped
out
> > after a systemm reboot?
>
> Yes, it is stored in RAM and wiped when:
> - The system is reboot
> - The name server process is stopped
> - You flush the cache with "rndc flush [view]"
>
> Yes, as the TTL on RR's in the cache expire, those RR's are removed.
>
>
> Perhaps you should invest a little time into reading the ARM.  You
have
> some great questions.  Most of the answers are in the docs...
>
>
> hth,
>
>
> Dave...
>
>
> >
> > Thanks.
> >
> >


Thanks for all of your help Dave. :-)  I work as a sysadmin and,
whenever I have an issue with which to deal and aspects of it are
unknown to me, I usually not only like to get the fix/quick answer but
also like to go completely "under the hood" to know how all of it
works.  BTW, one last question(maybe again indicative of the newbie :-)
), what does the acronym ARM mean?  Thanks again.



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