We have a network of 30 Windows 7 computers and 1 Windows 2k8 Domain controller. Prior to getting the Windows 2k8 Domain controller, we were using Untangle Firewall for DHCP services. There were NO problems with internet access at that time.
When we added the Windows 2k8 server to the network, I turned on the DHCP services on the Window 2k8 server and turned off the DHCP on the Untangle firewall. All clients were able to get IP addresses from the server, but, they couldn't get to the internet.
1. Turning off DNS on the Untangle firewall.
2. Adding the Untangle Firewall as a forwarder in server DNS settings (when DNS was enabled on the Untangle).
3. Adding the Windows 2k8 server to the DNS list on the Untangle Firewall (when DNS was enabled on the Untangle).
None of these things worked, so, had to return to using Untangle for the DHCP for the time being..