Explanation of DNS Notify List "Secondary Notification" Behavior

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.