Neophyte in a conundrum

[Rob Wright]

Greetings and salutations,

For the last three weeks I've been plagued by a group of users unable
to access a particular website behind a firewall at a financial
services organization. Everything was working fine up until then, now
they can't get to a page beneath the main page that sets on a seperate
IP address. When attempting to browse to it they are getting a message
"host not found". Trying to nslookup off my machine tells me that its
a "non-existent host/domain". Other name servers aren't having any
problems with this, and it seems to be just us. I have verified that
other services aren't having this problem. I understand that our
machine isn't resolving the address properly. We can go directly to
the site with the IP address. Here's some info:

1. We're running Bind 8 on a Linux machine (SuSE 6.2)
2. No changes have been made to my nameserver, and none were made
prior to the current trouble.
3. After the first incident, things seem to have cleared up on their
own for about a week, then went south again.
4. I've restarted the named, attempted to flush any cached
information, and used dig to update my cache.db file.
5. I did add another nameserver on another network to my resolv.conf
file, which allows the server itself to resolve the address, but it
still won't do it for other machines on the network.
6. The address we are trying to get to is behind a firewall, and does
seem to have port53 closed off.
7. I've checked over everything I can find, and pored through DNS and
Bind, and more docs and pages than I can count.

I'm sure I'm overlooking something, but I'm don't know what. I also
know that I'm probably not giving out enough info here, but as the
other machine is supposed to be a very secure system I'm not sure how
much I should divulge about them. If more info is needed to help me
out I'll be happy to supply what I can.

Thanks so much for any help you can give,

Rob Wright
rwright at nadaspam.poncacity.net