Hello, we have a client whose domain consists of 2 domain controllers - 1 DC at the main location and 1 DC at location B. The two locations are on different networks but are tied together via a VPN. We have just finished building a brand new domain on new servers for them. The new domain consists of two DCs (one which is 2003 and one which is 2008) and an exchange 2007 server - all at the main location. We would like to demote the DC at site B and promote as a DC to the new domain. My question is, what is the appropriate way to promote this DC at site B? Should it belong in a different site from the DCs at the main site? If so, can someone give me some documentation on exactly how we should set this up? Also, what is the benefit of having DCs in separate sites? Is it a requirement when DCs are on different networks? Thank you.

According to the post I understand that you have a Domain with 2 Domain Controllers located on each Site which is SiteA=1dc and SiteB=1dc. (OLD INFRASTRUCTURE) You again created a a brand new domain on new servers for them. The new domain consists of two DCs (one which is 2003 and one which is 2008) and an exchange 2007 server - all at the main location (NEW INFRATRUCTURE) If I understood you post properly then you should use ADMT tool for domain Migration http://www.microsoft.com/downloads/en/details.aspx?familyid=6D710919-1BA5-41CA-B2F3-C11BCB4857AF&displaylang=enhttp://www.virmansec.com/blogs/skhairuddin