Leia o texto a seguir.

Active Directory replication will seem logical if you’re already familiar with how replication works in Windows NT 4.0 domains. Each update is assigned its own 64-bit unique sequence number (USN) from a counter that is incremented whenever a change is made. These updates are system-specific, so every Active Directory server maintains a separate counter.

(Extraído de: “Active Directory. Microsoft TechNet.”

http://technet.microsoft.com/en-us/library/bb742424. aspx #XSL Tsection 122121120120)

De acordo com o texto,