A. ADMT 3.1 was designed to be used for the migration of Windows Server 2003 and Windows 2000 to Server 2008, Server 20003, and Windows 2000 domains. It's designed to be installed only on a Server 2008 server. ADMT 3.2 will support installation on Server 2008 R2 servers.
Microsoft has performed testing with ADMT 3.1 to a target of a Server 2008 R2 domain and do support the action, with a couple of gotchas you need to watch out for. They documented these in a Knowledge Base article.
- Plan and Execute an Active Directory Merger, Part 1
- Avoid Active Directory Pain
- Using Active Directory Administrative Center in Windows Server 2008 R2
- 4 AD Management Tools
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