In this article we will discuss about Aging and Scavenging and we will enable these features on our DNS server. Aging and Scavenging are two mechanisms used to mark and delete outdated resources. In large enterprises, these two features are used to provide a consistent DNS database used by all devices within the network. In such dynamic network it’s important that records are constantly updated so that DNS problems do not occur.
Aging is a mechanism that monitors the age of dynamic records and scavenging is a method that clears stale records from the DNS database. These two DNS features use timestamps configured on dynamically registered records so it’s important to remember that aging and scavenging is configured only on dynamically created resources.
Aging can be enabled from the DNS console. Navigate to the server’s name right click it and select Set Aging/Scavenging for All Zones from the menu:
The default values for scavenging is 7 days for both the refresh interval and non-refresh interval. You’ll have to check the Scavenge stale resource records box:
No-refresh interval – is the period between timestamp refresh. Each record is assigned a timestamp based on their role. The server will check the timestamps again after the no-refresh interval has passed.
Refresh interval – is the period of time in which the Server accepts timestamp refreshes. During the refresh interval no scavenging for stale resources is done. Only when both refresh interval and no-refresh interval have passed, scavenging can occur.
You can modify the refresh and no-refresh intervals suited but, these values should be OK for usual environments. With default values, scavenging will be done after 14 days. For resources that are created manually, timestamp values are set to 0 to indicate that aging and scavenging will not be performed on that particular resource. Also note that the refresh interval can be the same or higher value as the no-refresh interval to perform a correct aging and scavenging operation.
Aging and scavenging must be configured on the whole server and on each zone individually. By default, scavenging will not be enabled in Active-Directory integrated zones so check the Apply these settings to the existing Active Directory-integrated zones box if you wish to enable this feature.
Scavenging for stale records is the process of deleting records that are expired or are not used in the DNS namespace anymore. This operation can be done in two ways:
Manually – scavenging is performed by System Administrators using the DNS console. Open the console, right click the server’s name and select Scavenge Stale Resource Records. The server will then check the timestamps of all records from all the zones hosted on the server and will perform scavenging:
Automatically – to configure automatic scavenging on the server, you’ll have to enable automatic scavenging for stale records from the server’s properties in the advanced tab. All stale records are deleted during the scavenging period set here. The value can be set in hours or days:
Note that if you are using only AD-integrated zones, aging and scavenging is not required since these zones perform timestamping on their resources as soon as they are configured. Aging and scavenging should be enabled if you are using standard primary zones.
That’s it for this article folks, wish you all the best!