Mastering Active Directory

The high watermark vector table

The high watermark vector (HWMV) table is maintained locally by each domain controller to keep the track of the last change from its's replication partner for the given naming context. As you are aware, domain controllers have three naming contexts, which are schema NC, configuration NC, and domain NC. There will be an HWMV table for each naming context. The table contains the latest USN value it received from its replication partner for a given naming context. Based on that, the domain controller will decide where to start the replication process.