I have build up a parlell exchange server and i am restoring exchange backup from live running exchange to parlell exchange server . My plan is to replace live exchange server with parlell exchange server if in case live running server fails. My problem is adding compuer object to parlelll exchange server . We have 200 users in network. This parlell exchange server i have not connected to existing network . I am trying to add PC with same name and IP of exisiting PC names , but i am using same PC to do this job. Problem what i am facing is that the last name addedd only exists in domain. I want to know whether MAC address of NIC is being checked while adding to domain. Also , whether this is creating problem.