I have a classroom lab that students reconfigure as they are given new concepts. At the final stage, each pair of students has a domain controller for a child domain and a member server. The domain controller is multi-homed and connected to the member server via a cross-over cable. The domain controller runs a simple DHCP to provide a reserved address to the member server. The parent domain controller provides connection to 3 subnets 1) the left side of the room, 2) the right side of the room, and 3) the rest of the school including the DSL and NAT Firewall for Internet access. Both IP addresses for the (child) domain controller are static mapped (DHCP on the parent domain controller is at this point disabled), IP Routing is enabled, and each domain controller / router is exchanging routing table information via RIP V2 multicast. Each server (member servers and child domain controllers) are hosting multiple web sites with IIS. All of the servers can browse all of the lab’s web sites, routing packets through as many as 3 routers in the process.
Here’s the problem: using several configurations of DNS, the parent domain controller /router and the child domain controller /routers can all access the Internet through the firewall, but none of the member servers can get past the parent domain controller / router.
What can explain this?
I have a set of diagrams that I can e-mail to anyone interested in helping me solve this problem. Thanks.