Authorative and non-authorative answers..

Kevin Darcy kcd at daimlerchrysler.com
Mon Jul 17 21:31:31 UTC 2000


Amir wrote:

> Can anyone please clearify something ? when i nslookup , i get a list of
> ns's which i can get
> authorative answers from, and a list of Ns's i can get non-authorative
> answers from.
> what does that mean ? does that mean the authorative is the master(primary)
> server ? (if so , why do i see 2 names there sometimes ? can there be two
> masters ????)

I don't remember ever seeing nslookup spit out a "non-authoritative answers
can be found from:" line. Are you sure about that? Perhaps you are mixing
together "non-authoritative answer" with "authoritative answers can be found
from:".

In any case, "authoritative" doesn't mean just "master", it means "whatever I
(i.e. the answering server) happen to know as NS records for the zone". This
may be just the delegation information from the parent zone, or it could be an
NS list which was cached from a previous query that the server made for
something in the zone. There really is no completely reliable way to know
which server is actually master for a given zone, but then why do you need to?
Except for transient propagation delays, the slaves should know everything
that the master does anyway, so why not spread out the query load over several
servers? That's the whole point of replication in the first place.

Be aware too that sometimes the master doesn't answer regular client queries
-- a so-called "hidden master" -- so maybe *all* of the servers in the NS
records are actually slaves...


- Kevin





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