DNS Scavenging is a great answer to a problem that has been nagging everyone since RFC 2136 came out way back in 1997.Despite many clever methods of ensuring that clients and DHCP servers that perform dynamic updates clean up after themselves sometimes DNS can get messy. There are two big issues with DNS scavenging that seem to come up a lot: This post should help us figure out when the first issue will happen and completely avoid the second.Remember that old test server that you built two years ago that caught fire before it could be used? We’ll go through how scavenging is setup then I’ll give you my best practices.Scavenging will help you clean up old unused records in DNS.
If you actually run this command against a zone it will truly set scavenging and a timestamp on all records in the zone including static records that you never want to be scavenged. The timestamp may get updated on the server where the client dynamically registers but it will not replicate around to the other servers in the zone.This timestamp will be replicated around and the No-refresh interval begins again.If for some reason the client fails to update it’s record during the refresh interval it becomes One last thing before we leave the zone setting behind.The “zone can be scavenged after” timestamp is the first of your safety valves.It gives clients time to get their record timestamp updated before the big axe swings.All that is left is for somebody to come along, check all the timestamps and delete some stuff.This is done by any server that hosts the AD integrated zone.The second is when a record gets created by a client machine registering using dynamic DNS.Windows clients will attempt to dynamically update DNS every 24 hours. When a record is first created by a client that has no existing record it is considered an “Update” and the timestamp is set.Because of the time it takes scavenging to do it’s thing people find this command and get tempted to give it a try. Before a server will even look at a record to see if it will be scavenged the zone must have scavenging enabled.To access the scavenging settings for a zone right click the zone, select properties then on the general tab hit the “Aging” button. If you view it on any DNS server where this zone is replicated it will be the same.