Free Thinking

[Joseph S D Yao]

On Wed, Aug 30, 2000 at 10:14:15PM +0100, Quadri, Jay wrote:
> 
> 
> Why is it that when nslookup is used, the resolver does not move to the next
> nameserver in the resolv.conf to query it, it only does so if you set server
> option.  I would have thought it'll be dynamic.  ...

Because this is not how DNS works.  Once it finds a working server, it
does NOT go running around looking for other servers that might or
might not give the same answer or answers, which it would then have to
figure out how to merge, and how - using OR or AND? - and ...

It tries for correctness via simplicity.

Does this make sense?

If the first resolver does not respond, then it does in fact move on to
the next resolver.  As do your regular DNS routines.

>						?  Also the Windows resolver
> seems to be slightly different to Solaris.  The windows one is more forgiven
> in treading down the DNS search list  (not with nslookup, but with things
> like pinging etc.)

Not in my experience.

BIND is the "reference implementation."  As we all know by now, there
are other implementations, which may do some thing or another better,
or not.  But if the final answer is different from BIND's, it's wrong.

> Another question, do you know what the contents of the named.root file on
> A.ROOT-SERVERS.NET server on Internic.  I guess it would be the same
> named.root file used everywhere on the Internet.

Presumably.

The only places where you would use different root server files would
be in private, closed internets [lower-case] with their own roots.

I suspect that the root servers no longer need root hints files.  They
have their own authoritative root zone files, and BIND has not required
the existence of root server files when such hints are not required,
for a few sub-versions now.  But they were there before, and there is
no reason to have removed them.

-- 
Joe Yao				jsdy at cospo.osis.gov - Joseph S. D. Yao
COSPO/OSIS Computer Support					EMT-B
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