DNS error 4015 on backup DC servers if main DC is off

Question

Everything related to this error seams to be IP addressing issue so far but I cant see thats may case.

I have 3 -Domain Controllers(Windows Server 2019): lets call them DC1, DC2 and DC3.
DC1 and DC2 are located on same site and DC3 is on remote site.

DC1 - is main server (operations master).
As a DNS IP it has DC2s IP address and itself.

DC2 - for backup and redundancy.
As a DNS IP it has DC1s IP and Itself.

DC3 - serves as Domain Controller and DNS for remote site
As a DNS IP it has DC2s IP address and itself. (No DC1s IP at all)

when DC1 is up and running I have no events or issues. Also, dcdiag.exe shows no issues.

When DC1 is off I see 4015 error logged every 5min on DC2 and DC3 ( which is remote server)
Strangely Im also loosing DFS management to my Namespace though I still can access my share and users not having issues. This could be somehow related with DNS errors I guess.

If main DC1 is off and I run dcdiag it complains that role holder is nor reachable as expected.

I have flushed, reregistered, restarted DNS server on DC2 but still same outcome.

Also not having DNS or AD/DS replication issues, as lets say if I create entry on DC2s DNS while DC1 is off, when DC1 comes back it replicates from DC2 and all records are equal.

I would highly appreciate any suggestions or thoughts.

Answer 1

Sounds like problematic DNS configuration.
https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/dd349575(v=ws.10)?redirectedfrom=MSDN

Short outages of the PDC emulator should be a big deal. If there is going to be an extended outage you may want to transfer the roles to another healthy domain controller.

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Answer 2

I have tried that, restarting servers doesnt log any errors or warnings.
Even if I stop main DC1 DNS Server completely non of other server DC2 or DC3 complain or log any error.
I assume this is not related with DC1 DNS and its something else?

So when you say short outage of PDC emulator is big deal, is this behaviour expected? Or there is some issue behind that?
Im not shutting down main DC1 longer then and hour to see what happens next, but as soon as its of DNS error 4015 logs every 5 min on all servers.
Even on servers not pointing to DC1 in their DNS entry.

Any other troubleshooting steps for this?

Answer 3

Hi,

Thanks for posting in Q&A platform.

Before we go further, could you please help to provide screenshot of the Event 4015 with specific errors for further troubleshooting?

Best Regards,
Sunny

Answer 4

This is when DC1(main server) is off. This error comes up straight away after 5 min and keeps logging

Answer 5

Hi,

Thank you for your feedback.

For testing, could you please configure the zone to allow both non-secure and secure update on DC2 and DC3 when DC1 was down? Then please kindly check if event 4015 is still occurred.

If the issue still existed, please run the following command in DC2 and DC3, and please share the results for us further troubleshooting. (Please remove the information which may leak your private information)

Dcdiag /v >c:\dcdiag1.log

Repadmin /showrepl >C:\repl.txt

*Repadmin /showreps *

Best Regards,
Sunny

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