I have a Windows 2003 server domain and around 50 users. While I was checking the DNS yesterday, I have found that its not resolving external websites from any of the domain computer. I checked through nslookup > www.google.com, I get the error DNS request time out timeout was 2 seconds request to pdc.mydomain.org timed-out. If I try to resolve internal computers then they resolve easily. When I set the external DNS servers (OpenDNS) on the forwarders of DNS, then it resolves with the message as non-authoritative answer:
Please note that I am using OpenDNS along with ISA server 2006 for monitoring internet activity. Through ISA, it also resolves but with the same message non-authoritative answer.