I haven't encountered this problem before...
I have a LAN domain with one domain controller and about 15 users. I had two switches: one 24-port PoE (Power over Ethernet) switch, and one plain 16 port switch. Today I replaced the plain 16-port switch with a brand new Dell PowerConnect PoE switch. I hooked the two PoE switches together with a single Ethernet cable connecting their gigagit ports.
Subsequent to the replacement all the user computers work normally and have access to the Internet, however the domain controller suddenly can't access Internet via either IE or Firefox. This is a problem because several services on the server can't obtain automatic updates from the Internet. The server also hosts Exchange, but email is still flowing.
I can ping www.yahoo.com
from a DOS box on the server, which is strange, since I can't reach the Internet via a web browser. There is no software firewall running and I have tried disabling the antivirus program.
I think I need help with DNS to troubleshoot this?