max-ncache-ttl

[Simon Waters]

"England, Robert" wrote:
> 
> If decreasing the time for the negative cache is not a good thing, any ideas
> of what I can do to help us resolve the domain names. We have mail that sits
> in the queues. We have a current db.cache file. Could the problems be
> Internet Latency?

What Barry is saying is that the symptom you describe is because
the domains or DNS are set up wrong, and may have nothing to do
with the server that is resolving them. If you have high
latency, you fail to get an answer, this isn't cached (Although
BIND remembers if a server is particularly slow in responding so
it can try others first).

NXDOMAIN is only cached if something tells you that a domain
doesn't exist. So reducing max-ncache-ttl may help you requery
one of the servers that is working correctly, but it doesn't fix
the broken servers.


Mail sitting in queues should be a DIFFERENT problem, and not
caused by NXDOMAIN responses.

If I mail fred at nonesuchdomain.com I get an NXDOMAIN from one of
the GTLD-SERVERS.NET.
Immediately my mailer gives up and says;

<fred at nonesuchdomain.com>: Name service error for
nonesuchdomain.com: Host not found

Why would a mailer hang on to mail for a domain that doesn't
exist? It can never be delivered? (Unless someone registers
nonesuchdomain.com, and sets the DNS up shortly after you sent
the message ;).

Are you sure your getting NXDOMAIN, and not some other error?
What does "mailq" show?