Removing DHCP failover removes DNS A records RRS feed

  • Question

  • We are running a windows 2012 r2 domain with 4 DCs all configured as DNS servers. One of the DCs is also our DHCP server. We configured a second dhcp server in January and joined it in failover mode. It was fine for a couple weeks, but then we got spammed with 20291 and 20292 errors. We decided to remove the failover relationship and unauthorize the second dhcp server which we did without any errors. However when we rebooted the original dhcp server, we immediately lost over 30 A records in dns, mostly printers, and we found that the dns server ip addresses on the nics of the dhcp server were changed to invalid addresses. Is there anything known that could explain this behavior? Otherwise the server seems to be working fine, and diagnostics (dcdiag, repadmin, event log) are not showing any errors.
    Wednesday, February 18, 2015 5:18 PM


  • Hi,

    Was the second DHCP server also a DC? Which kind of DHCP Failover Modes did you used?

    Based on my experience, a DHCP server can register and update DNS PTR and address A resource records on behalf of its DHCP-enabled clients. I assume the lost A records may be due to the IP address of the DNS server was changed. Did you configure a static DNS server in the DNS settings on the DHCP server? I assume that you select "Obtain DNS server address automatically" as if you define a DNS server, it won't be changed after reboot.

    In general, it would be better to point the preferred/secondary DNS server to the DC instead of obtaining the DNS server address automatically.

    Besides, for event ID 20291, you can refer to the KB below:

    Best regards,


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    Friday, February 20, 2015 6:47 AM