So you say these domain controllers are syncing together? I would say get them sorted in Sites and Services. Rename the Default-First-Site to something more relevant (e.g HQ). Create a new site again giving it a relevant name. Create a subnet for the new network as well as one for your HQ's if you haven't done so already, matching the subnet to the site. Right click the server in the branch office and move it to the new site. Inter-Site Transports > IP. Rename the DEFAULTIPSITELINK (e.g HQ<>Branch). Right click > Properties. Add the new site to the site link. If you need to change any replication schedules. Im not sure about the exchange side of things. If its working ok as it is at the moment then nothing should change. When I have done it I install an Exchange into the new branch office. Mail all comes in at the head office end where the Exchange there distributes it to the correct server depending on which Mailbox Store the users account resides on. The question about FMSO roles is an odd one. If your two DC's are indeed communicating at the moment then there will only be one DC with these roles. Typically this is the first DC for the domain unless someone's changed this. Nothing needs to change. What I will say though is make both servers GC servers. You should always have at least one GC server at each site. Now that you've told AD Sites and Services more information about the network it resides on it will use this to check which server is most local to a user. Hopefully this will put an end too any slow access your users are experiencing. Apart from Exchange I guess.