Single Sing-ON Windows Server

Hello. The current infrastructure is: 3 Domain Controllers located on different sites that are running on Windows 2008R2 with FFL and DFL 2008R2 wilh Global Catalog and DNS with 500 users and computers. Root and Internal Certificate servers 2008R2 with hash algorithm SHA1 Windows 7 Enterprise.

Windows 2008 VPS via Single Sing-ON Windows Server.