I have a ISA 2006 Server as the network firewall. I have Active directory domain controller in the internal network and there are a couple of web servers (IIS6) in the perimeter network and I want the perimeter web servers to authenticate to the AD which is located in the internal network. Any advice/help? both of the internal network adn the perimeter network is separated by ISA 2006. I have opened all of the ports etc but no luck. Much appreciated if someone can help me.