Windows 2003 Active Directory Server - 2 other servers and 25 workstaitons -xp. Snapgear firewall. Not a large network.
Internet has been fine until recently it has become very slow. workstations are set up to obtain dns info from server. dhcp has the ip address of our internal dns server for primary and we have no secondary. If i manually change a workstation's dns servers to that of our ISP's then it becomes very fast. If I put it back to obtain dns info automatically then it slows way down again. I can't see that anything has changed except the speed of our internet.
Am I supposed to be using forwarders on my DNS server? The only place that I have our ISP DNS server's IP addresses are on the firewall right now. Help.