I currently have a Domain Controller Running on the Windows 2003 Operating System and Forest Functional Level 2003. I also Have a Microsoft Exchange 2007 Server and Windows 7 clients as part of that same AD Domain. My goal is to add a Domain Controller with the latest OS to the current Active Directory.
My question is, what is the highest Operating System and Functional Level I can run on an added Domain Controller without having to upgrade the Exchange Server 2007 and temporarily keep the current Windows 2003 Domain Controllers? Once we have tested this new Domain Controller works properly, we intend to demote the Windows 2003 Domain Controllers.
Steps to accomplishing this would be greatly appreciated.