Microsoft Windows NT Primary Domain Name Service (DNS) Servers do not send
change notification messages to Secondary DNS Servers that are included on
the Primary's Notify List until selecting the menu option "DNS/Update
Server Data Files".
Microsoft Windows NT DNS Server allows the Administrator to specify (on the
Primary DNS Server) any Secondary DNS Servers that should be notified
immediately of changes to the Zone file. When Zone changes occur, the
Primary name server sends DNS change notification messages to all Secondary
name servers on the list. When notified, the Secondary name server can
query the SOA record on the Primary immediately, without waiting for the
Refresh Interval to expire.
The notification process does not occur until the "DNS/Update Server Data
Files" menu item is selected. Since there is no Incremental Zone transfer
capability, when a Zone Transfer is triggered, the entire Zone file is
transferred - not just changes made to the zone file.
Normally, the Administrator will make several changes in a single
administrative session. If the Secondary DNS Servers were notified after
every change, there would be a continuous stream of Zone transfers during a
single session, generating unnecessary network traffic. Waiting for the
Administrator to trigger the process by selecting "DNS/Update Server Data
Files" prevents continuous Zone transfers.