On our AD domain, end users desktops take a long time to resolve DNS from outside our company. Internally everything works fine.
The desktops are pointing pointing to 192.168.2.4 and .6. Those are the two domain controllers. .6 is currently down to be rebuilt, but it is the second DNS server listed in the TCP/IP settings. I dont think that is the issue.
The working DC's first DNS is pointing to our ISPs DNS and the second is set to 127.0.0.1. Using a browser on the server works as expected, external DNS resolution is quick.
Am I missing something obvious? Why are the desktops resolving DNS so slowly?