3.1.1.2 Version
Whenever a name record is updated that needs to be replicated, the NBNS server increments the global version counter and updates the version field of the Name Record with the current value of the global version counter. Such changes occur when:
The name record is newly registered.
The name record transitions back to active state from released or tombstone state.
The name transitions into tombstone state.
The name record is a replica but is refreshed locally.
The name record has a change of address due to a refresh.
The administrator changes the address of a static name record.
A new address is added to the name record (in case of a special group or multihomed entry). This can be due to a local registration or because of replication of an address owned by another NBNS server (for a special group or multihomed entry).
The version number of name records MUST be monotonically increasing. The name records (including version numbers) MUST be committed to stable storage so that the version can be monotonically increased between reboots. After the NBNS service is restarted, the new version number MUST be greater than the last version number before the service shutdown.
The version number and state of name records that are owned by other NBNS servers are replicated to the local NBNS server, and are not directly changed unless the client corresponding to the record updates it at the local NBNS server. When this happens, the record—and in case of a special group or multihomed record, the address registered by the client—becomes owned by the local NBNS server.