Using DNS Notify in Windows 2000 Server

DNS Notify in Windows 2000 Server is more efficient than polling in that it allows a secondary server to not have to ask the master server at regular intervals -- but it's not automatic. Learn about using DNS Notify in Windows 2000 Server.

Primary DNS servers, such as Windows 2000 Servers, use zone transfer to send zone changes to secondary servers. This zone transfer is based on polling, whereby secondary servers ask master servers at regular intervals for any changes. If there are changes, the master server sends them to the secondary server.

The interval is defined by the Refresh field in the zone's Start Of Authority (SOA)record. To change that interval, go to the DNS console (Start | Programs | Administrative Tools | DNS), right-click on the zone, and select Properties. The Refresh interval can be changed on the SOA tab. The default interval is 15 minutes.

Another, more efficient mechanism supported by the Windows 2000 DNS service is DNS Notify (RFC 1996). DNS Notify is a mechanism by which the master server for a zone notifies secondary servers of zone changes. This way a secondary server doesn't have to ask the master server at regular intervals and is more efficient than polling.

Before a master server can notify secondary servers, you have to create a special Notify list that specifies all servers to be notified. The master server will notify only the servers on this list. To configure DNS Notify in the Windows 2000 DNS service, open the DNS console, right-click on the zone for which you want to set up DNS Notify, and select Properties. On the Zone Transfers tab, check the Allow Zone Transfers check box and click the Notify button.

In the Notify window, enable the Automatically Notify check box. You can then choose between Servers Listed On The Name Servers Tab and The Following Servers. With this setting, you're selecting the servers for the Notify list.

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