Domain Controller has multiple DNS entries (uppercase & lowercase) -- Update did not fix

Beth Conte 1

Mixed 2012 R2 & 2016 environment. The PDC name has upper & lower-case letters (dangit!). Once we added a 2016 domain controller, multiple records were generated for the PDC. I know this is a known issue, but the update did not fix the problem. Unfortunately, the presence of multiple LDAP records seem to confuse AD. On 2016 DCs, I changed the registry entry to use lower-case. The upper-case records remain. I deleted the upper-case records, but they keep coming back. Is there anyway to permanently delete these stale records? I would prefer to not demote my PDC, rename it then promote it.

Thanks!

2 answers

Anonymous

2022-02-21T22:04:29.683+00:00

Maybe the work-around #1 mentioned here.
https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/dns-registers-duplicate-srv-records-for-dc#workaround-1-prevent-duplicate-srv-records

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Anonymous

2022-02-24T13:32:35.727+00:00

Just checking if there's any progress or updates?

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Beth Conte 1 Reputation point

2022-02-24T15:51:25.24+00:00

Hi DSPatrick,

I've reviewed that article before. I did not try setting DNS on 2012 R2 machines to only point to other 2012 R2 machines and 2016 to 2016. Since it is AD-integrated, I didn't think it would work. They talking about settings in the NIC, yes?? Anyway, it will have to wait until the weekend, because one of the 2016 machines is in Azure and requires a reboot to change DNS server.

I will let you know how it goes.

Anonymous

2022-02-24T16:06:40.683+00:00

Ok, sounds good, in the end it may be simpler to just get rid of the 2012 domain controller.

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Beth Conte 1 Reputation point

2022-02-24T16:32:20.453+00:00

We have four 2012 R2 DCs. We will be replacing them soon, but need reliable DNS until that time. :)
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Anonymous

2022-02-24T16:46:57.977+00:00

Once we added a 2016 domain controller, multiple records were generated

Actually this was fixed sometime back.

March 17, 2020—KB4541329 (OS Build 14393.3595)
Addresses an issue that might cause domain controllers (DC) to register a lowercase and a mixed or all uppercase Domain Name System (DNS) service (SRV) record in the _MSDCS.<forest root domain> DNS zone. This occurs when DC computer names contain one or more uppercase characters.

so I'd check that the new ones have been patched fully.

also
https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/dns-registers-duplicate-srv-records-for-dc#resolution

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Beth Conte 1 Reputation point

2022-02-24T17:29:37.903+00:00

They are fully patched. I have tried downloading and installing this update separately and it says the update is not applicable...

Anonymous

2022-02-24T18:23:00.823+00:00

Might try cleaning up the records, might be they're from a time before the server was patched.

says the update is not applicable

Yes, that's expected behavior.

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Beth Conte 1 Reputation point

2022-02-24T18:32:02.72+00:00

I've deleted the duplicate records many times. They keep coming back.

Anonymous

2022-02-24T18:35:46.547+00:00

I suppose it must mean the 2012 domain controllers are responsible for this then.

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Beth Conte 1 Reputation point

2022-02-24T18:55:49.243+00:00

2016 is the one who sees the machine w/ upper and lower-case letters in it's name as two separate machines. 2016 is the problem and the patch doesn't seem to work.

Anonymous

2022-02-24T19:02:11.483+00:00

As mentioned here KB4541329 addressed this issue directly.

March 17, 2020—KB4541329 (OS Build 14393.3595)
Addresses an issue that might cause domain controllers (DC) to register a lowercase and a mixed or all uppercase Domain Name System (DNS) service (SRV) record in the _MSDCS.<forest root domain> DNS zone. This occurs when DC computer names contain one or more uppercase characters.

If you believe that's now broken you could open a case with product support. All cases closed as bugs are refunded.
https://support.serviceshub.microsoft.com/supportforbusiness

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Anonymous

2022-03-01T14:25:32.58+00:00

Just checking if there's any progress or updates?

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Domain Controller has multiple DNS entries (uppercase & lowercase) -- Update did not fix

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