This one bugs me a little bit, why this is not enabled by default in Microsoft’s Active Directory, DNS Scavenging.

The idea behind it is simple, when a computer is joined to the domain, it creates a DNS record in Active Directory Users & Computers. From there you have to manually remove the record when a computer is taken off the network, otherwise another computer that get’s that IP also resolves to that name. Wait What? Oh yea, these are the guys that designed the Metro UI as well, Microsoft, so it only makes sense that something as important as this would have to be disabled by default.

go into your DNS settings

(note that you should only do this on one (usually your primary if you have multiples) DNS Server on a network, otherwise conflicts can occur. 

Enable these settings (note what this does is sets when the dns record will refresh, and what the maximum period is before the record is scavenged.

Final step: Wait

the process for this can take up to 7-10 days depending on your network, but slowly but surely you can cleanup your DNS names without having to do any real work.

That’s It!