We have 2 synchronized DNS servers in our domain, both running Server 2003. Upon arrival this morning, I noticed that accessing external websites is very slow however, accessing shares/servers on the LAN is fine. After changing the DNS server on my laptop to an external server (188.8.131.52) the speed in which I could access external sites picked up tremendously. What could have changed overnight that is slowing down DNS?
You want to see what the forwarding servers are set to on the DNS servers. These are the servers that are used when a record doesn't exist locally (say, when visiting another site on the Internet). One of the forwarders may be responding slowly.