Multiple entries in DNS forward lookup zone

November 25, 2010 at 07:18:25
Specs: Windows 7

I have DCHP and DNS running on a Server 2008 R2 Domain Controller. I have noticed multiple entries in DNS with the same IP address but different hostnames. When I check the owner of the entry in DNS one is the DHCP service and the other is a client machine i.e hostname$

The DHCP registered entries are correct and seem to clean up after themselves by removing entries when either the lease expires or is released. The host entries however do not.

I have scavenging/aging of stale records for no-refesh and refresh set to 7 days for all zones, should this possibly be shorter.

Windows clients do have the register this connections addresses in DNS checked in the adapter properties, this must be the default setting.

I suspect reducing the scavenging interval may help but how short is advisable?
I have read else where a GPO to change client NIC properties might also be a solution but that seems a lot of admin. How do others address this issue on the LAN?

As a thought is it possible to restrict the security permissions on the DNS server so that clients don't have permissions to register themselves leaving DHCP to do it?

Any suggestions welcome, thanks :)

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November 27, 2010 at 09:34:07
You don't mention any name resolution issues. Are you having issues you are trying to address?

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November 29, 2010 at 00:52:41
Hi wanderer, yes the result of the above is incorrect name resolution for some client machines with duplicate entries. Scavenging/ageing was not set at the server level which I have now done. I have manually removed the duplicate entries created by the workstations and with the oldest timestamps. I'm envisioning that I'm still going to get a few duplicate entries from both machine and DHCP though, although they should know eventually be removed with scavenging/ageing set.

So the issue I'm trying to address is incorrect DNS resolution for some clients due to duplicate entries. Which the cause appears to be clients registering themselves in DNS and the records going stale and not being removed. This will be addressed to some extent by scavenging and ageing but I suspect a time lapse where two entries will exist.

What is best practice for LAN clients using DHCP/DNS in a Microsoft environment?


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November 29, 2010 at 11:31:17
perhaps this will help

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November 30, 2010 at 06:31:11
Thanks I'll have a read through it

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