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How do I remove multiple entries in the reverse DNS table?

I need some help with the reverse lookup zone table on my Windows 2000 server. I have multiple names for most of the IP addreses and this is obviously wrong. I beleive a new entry is created if the client has obtained an alternative IP DHCP address, or maybe when the client PC has been rejoined to the domain (But they are only guesses) The entries are similar to the following:-      Pointer      zurich.mydomain.local.      Pointer      bilge.      Pointer      thecon.mydomain.local.      Pointer      sphere.      Pointer      centurian.mydomain.local.      Pointer      kingston.      Pointer      amidala.mydomain.local.      Pointer      amidala.      Pointer      kingston.mydomain.local.      Pointer      overtone.      Pointer      bismarck.mydomain.local.      Pointer      calcium.      Pointer      fred.mydomain.local.      Pointer      maul.      Pointer      norton.

I have no real problems on the network at the moment, but I have had some issues with group policy failing at login from time to time on several pc's.

Does anyone know the answers to the following:
1. What could cause the multiple entries to be created
2. When does the reverse table get used?
3. Can I recreate the table on the fly to correct the problems
4. What effect could I see if I didn;t rectify the problems
5. Why do some of the entries in the table have the extension .mydomain.com as opposed to just the name?

Many thanks

Andy Coggin
1 Solution
When you rename a machine it will create multiple entries in your DNS table in windows 2000 domain. I have w2k DC myself and it seems to be a common problem with w2k server - looks like it fails to remove old records when they expired.

The Reverse Lookup zone is used to resolve IP -> Name request. Just like the Forward Look Zone but in the opposite way.

I think you can recreate a new Reverse Look Zone. Of course it will bring interruption to your business but it shouldn't take long to recreate one. If you don't have a long list it might be better to manually removing the old records, providing you know which one is active and which one is inactive.

You get entries without the proper domain name especially when someone plugs a "private" laptop in the network. If you bring your home laptop in (which is NOT on the domain) it still registers itself to the DNS database with its name.

Effect - you might experience with lost network packets sometimes but not always.
Goto the properties of the DHCP server in the DNS tab what settings have you enabled
ACogginAuthor Commented:
Found this on Technet, looks like I might have either a config problem in DHCP or a bug. The DNS pointer records should look after themselves. I'd still like to know when they are used, apart from when I perform an nslookup! Do you know if they are used in the day to day communication of the client / server, or the logon process?

" Computers use the DHCP Client service to dynamically register and update their PTR resource record in DNS when an IP configuration change occurs.
" All other DHCP-enabled client computers can have their PTR resource records registered and updated by the DHCP server if they obtain their IP lease from a qualified server. The Windows 2000 and Windows Server 2003 DHCP Server service provides this capability.
gary - which setting do you think I should check, Admin Tools \ DHCP or Admin Tools DNS?


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Goto the DHCP MMC and right click on the server goto properties and then the DNS post back what options are enabled
Brian PiercePhotographerCommented:
Looks like you need to enable aging and scavenging to automatically delete stale records - see http://support.microsoft.com/kb/296116
ACogginAuthor Commented:
Thanks for all your help with this issue - enabling scavenging as per the above article resolved the problem.
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