We've recently had some issues where resolving external domains fails for clients using internal Windows 2000 DNS servers. This happens every
12 to 24 hours and is fixed by simply restarting the PIX.
During the problem, when substituting the internal servers with external DNS servers supplied by our ISP , resolving external domains works fine.
Note that nothing has changed on the servers themselves, so this leads me to believe there may be a problem with the PIX itself. This has also coincided with some changes made by a third party consultant on the PIX about a week ago. However we cannot yet determine what change may have had an impact, as nothing to do with DNS was changed at the time.
On the PIX, we have always had the following line in the config:
fixup protocol dns maximum-length 512
As I'm not an expert on PIX firewalls, has anybody had a similar issue or can anyone suggest the best way to resolve this?
I can also reprint the entire config here if required.
thanks