DNS Delegation is Broken - "double domain"

Lanky Doodle 226 Reputation points


When running DCDIAG I can see this error, for a "double domain":

DNS Delegation for domain.xyz.uk.domain.xyz.uk is Broken on IP x.x.x.x

When I look in the DNS zone domain.xyz.uk, there is no delegation listed for domain.xyz.uk. However we do have other delegations that show under this zone, and show in DCDIAG as passed OK.

Because of this failure, DCDIAG is showing FAIL for the Delegation test on all DCs.

Where can I check to make sure this double domain isn't actually ghosted somewhere?


Active Directory
Active Directory
A set of directory-based technologies included in Windows Server.
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Windows DHCP
Windows DHCP
Windows: A family of Microsoft operating systems that run across personal computers, tablets, laptops, phones, internet of things devices, self-contained mixed reality headsets, large collaboration screens, and other devices.DHCP: Dynamic Host Configuration Protocol (DHCP). A communications protocol that lets network administrators manage centrally and automate the assignment of Internet Protocol (IP) addresses in an organization's network.
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  1. Thameur-BOURBITA 32,596 Reputation points


    Some links talking about the same issue may help:



    Please don't forget to mark helpful reply as answer

  2. Vicky Wang 2,646 Reputation points

    On the new 2012 Domain Controller, In DNS Management > Forward Lookup Zones > mydomain.com > there was a "COM" folder here. Under the "COM" folder was a folder named "mydomain" in which contained 2 CNAME records for Lync at Office 365.We're not using Lync, so I proceeded with removal of these records.

    Once I deleted the parent "COM" folder, dcDIAG's & Nslookups reported correctly. I did however demote the old domain controller before discovering this (by minutes). yes the DC promo wizard burped about not being able to remove the delgated domain "com". I found this interesting that the wizard was representing a COM domain and not mydomain.com It was this that is what led me to this discovery in DNS on the new DC.

    Hope this information can help you
    Best wishes

  3. Vicky Wang 2,646 Reputation points


    Just checking in to see if the information provided was helpful.

    Please let us know if you would like further assistance.

    Best Regards,