The past couple of weeks I've been experiencing issues with random DNS drops that I haven't been able to identify a cause for the trouble or evidence of a problem on my DNS servers. What is happening is that randomly across a mix of Windows XP and 7 systems the systems will no longer be able to resolve and connect to anything by internal DNS reference, this is most noticeable with GroupWise which we do not have an external DNS reference for clients to connect to.

Most often what happens is that we get a call that the user can't connect to GroupWise, I'll remote into the system and 99% of the time an ipconfig /flushdns fixes the issue. In the few cases that flushing the DNS doesn't work, stopping and restarting the DNS Client Service on the workstation fixes the issue.

I have 2 internal DNS servers, my more recent one that is on a SLES 10 OES 2 SP3 system virtualized on a SAN, and an older system which is on a Netware 6.5 SP8 system on physical hardware. DNS services are up and running on both servers. We assign all of our IP addresses statically so don't have DHCP in use, and we don't have DNS configured to allow workstations to write their names to DNS, so our DNS tables only have what we have manually created through iManager or the DNS/DHCP application.

Any ideas why DNS is suddenly going flaky on me? Thanks!