A+ Replication in Server 2003

Server 2003 has a directory partition type, the Application directory partition, only on Windows 2003 DCs. Applications and services use this partition for application-specific data. Creating, modifying, moving, and deleting an object trigger a replication between domain controllers. Replications are either:

• Intrasite (within a site) replication mostly use LAN connections. Intrasite replication does not compress data, so it saves CPU time.  The replication partners poll each other periodically and notify each other when changes need to be replicated, and then pull the information for processing. Active Directory uses a remote procedure call (RPC) transport protocol for intrasite replication. 
• Intersite (between sites) replication uses WAN connections; large amounts of data are compressed to save WAN bandwidth. Replication partners do not notify each other when changes need to be replicated to save bandwidth. Instead, administrators configure the replication schedule to update the information. Active Directory uses an IP or SMTP protocol for intersite replication.