Friday, December 9, 2011

How to configure scavenging under DNS in Windows Server

Here are the step for configuring DNS scavenging 
-Go to the  server properties page and choose "Set Aging/Scavenging for All Zones".

-Choose the no-refresh and refresh interval as appropriate.

-Best practice is to choose a low no-refresh interval of 1 day.

-Refresh interval will be one more than the lease period of the client as a best practice.

-If we have a very large lease period, the results of scavenging will be visible after a long time.

-Example with a lease 5 days, no-refresh to be 1 day and refresh to be 6 days, we might not see any effects for  5+1+6 days' time.

-Identify the zone which you want to enable for scavenging and the ones you don't want to.

Scavenging configurations:

-Right click the specific zone, select Properties, and go to the General tab; click the Aging button. Set the no-refresh and the refresh intervals as per best practice above.

-There are 2 options to kick off scavenging.

a) Right click the server name, select Properties, and choose "Scavenge Stale Resource Records" (This should give an informational event in the application log telling if the scavenging was successful or not). Then, configure the scavenging engine to run automatically and periodically, go to the server's Properties, Advanced tab and check "Enable
Automatic scavenging of stale records".

b) If option 'a' fails, then first identify the manually created records in the specific zone by the following
    dnscmd /enumrecords <zone name> @ > manual.txt -The above command will pipe the output of the zone records to text file in the current directory.
-Then the records which do not have an aging value specified are the ones which have been manually created.

-Identify the static records that you want to keep from deleting.
-Run the following command:
    dnscmd /ageallrecords <zone name> @
-The above command will put a time stamp on each record including the static ones.
-Then go to the view menu on the server and enable advanced view.
-Go to the properties of static records you want to keep and uncheck the box 'Delete this record when it becomes stale'.
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