what exactly is the zone name used for?

Kevin Darcy kcd at daimlerchrysler.com
Thu Jan 6 23:35:36 UTC 2000


Joseph Morrison wrote:

> Hello all,
>
> If you have the following in your named configuration file:
>
> zone "aaa.com." {
>         type master;
>         file "named.aaa";
> };
>
> Then what exactly is the "aaa.com." used for? Is it ONLY used to expand
> abbreviations in the "named.aaa" file? Or is it used for anything else
> (like considering itself authoritative only for the domain specified
> after the zone keyword)?
>
> I'm considering including information for multiple domains in a single
> "named.aaa" file, and using the name of the first domain after the
> "zone" keyword. Is there any downside to doing that?
>
> I have a similar question for reverse mappings; if I want to provide
> authoritative PTR records for multiple subnets, is it possible to put
> them in a single zone file? And if so, what should be specified
> immediately after the "zone" keyword?
>
> Thanks for any answers or pointers to information,

Read RFC's 1034 & 1035 and also the _DNS_and_BIND_ O'Reilly book. The zone
name is not just a syntactical convenience; it also defines where in the
overall namespace hierarchy the zone is located. If you were to name your
zone "bar.foo", for instance, your server could resolve names in that zone,
but no-one on the Internet would be able to resolve them, since the Internet
root servers know nothing about a "foo" top-level domain (or, if they do,
they're not telling anyone about it  :-).

As for putting information of multiple zones into a single file, this is not
a feature currently supported by BIND, and not likely to be, as it would
greatly complicate parsing. I note, however, that BIND 9 promises more
choices of backend data stores, including databases. This should allow one to
reap the same kind of benefits as having multiple zones in a file.


- Kevin





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