strange lookup problems - setup problem?

[Torsten Curdt]

Our internal nameserver sometime fails to lookup
some domains e.g. the domain f2s.com.


I configured for unknown zones:

zone "." IN {
        type hint;
        file "root.hint";
        check-names warn;
};


But sometimes I get a timeout when requesting
it on our name server.

 dig www.f2s.com

Trying the following name server

 dig @gwdu01.gwdg.de www.f2s.com

gives me always the desired result.
While trying the following name server

 dig @pns.dtag.de www.f2s.com

gives me a listing of the root servers.


Why is that? Shouldn't all of them give the
desire address? Why might I get listing of the
root servers instead? I'm a bit confused.

Could I forward the requests for zone "."
to a list of other name servers?

Any hints appreciated
--
Torsten