When changes are made to the zone on a master server, these changes must be replicated to all the secondary servers for that zone, using a mechanism called zone transfer . In the original DNS specifications, only one form of zone transfer was available, known as full zone transfer. New RFCs discuss an additional type of zone transfer: incremental zone transfer. This section describes both types. It also describes DNS Notify, a mechanism by which the master server for a zone can notify the secondary servers of zone changes.