Active Directory multiple environment solution

What would be the best solution to control 3 different environment with one active directory? 3 different rooms, each with 10 machines. 1. 192.168.0.x 2. 192.168.1.x 3. 192.168.2.x All of them connects via CISCO ASA to a server with active directory on it. Not quite sure how can i add all of them under different "groups" as in every room there are computer with the same names. Thanks!