Connecting 2 different domains, same physical location. We have 2 separate networks, each with a different domain. Each network's domain controllers and servers are in the same physical location. Each network/domain has its own router and public address. If I connect a port on a switch on one of the networks (192.168.10.X) with a port on a switch used on the other network (192.168.150.X), that is behind the router and firewall connections, will the different networks be able to communicate with each other? (ping, shared folders, etc.) If I set up a trust relationship between my 2 networks, so that they have the same forest, would my switch to switch connection work then?

Are these domains in the same forest or not? Just connecting the networks physically is only half of the issue. You have to put a router in between them if you wish to maintain the two subnets.

We were able to set this up by changing the 2 domain controllers that we wanted to connect by changing the subnet mask to 255.255.0.0. Then we were able to setup the trusts between them.

I take it you supernetted the subnets and did a forest trust then?