small question re caching only name server syntax

[Kevin Darcy]

Don Low wrote:

> I've been modifying /etc/named.conf to function as a caching only name
> server for BIND 9.2.1.  One thing I'm mixed up about is why you should
> include zone info as in:
>
> zone "." IN {
>   type hint;
>   file "root.cache
>
> Why would you include reference to a local root.cache when anything not
> cached locally causes the name server to query the ISP name servers.

Why do you assume the nameserver is going to query the ISP nameservers? Do
you have forwarding enabled? If that's the case, then you are correct: you
don't need a hints zone definition.

If you don't have forwarding enabled, then your nameserver needs to start
*somewhere* to be able to resolve Internet names. The function of the hints
file is to tell the nameserver where to get root-zone information when it
first starts up. Once it knows about the root zone, then it can follow the
branches of the delegation tree to resolve anything else it needs to.

> Some
> named.conf files I've seen include zone information and others don't even
> have a zone section.

That's a bit kludgey, but what happens if you don't have any zone definition
at all for root is that named uses a compiled-in default list of root
nameservers. If the root servers ever change -- this tends to happen very
infrequently, for obvious reasons -- then this compiled-in list could become
slightly sub-optimal.


- Kevin