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  • DCdiag errors, possible DNS related

    Hey, folks, we ran into two problems this evening (Zimbabwe time zone, GMT+2). One, the major one, is an issue with our dcdiag results. We have two AD Controllers, 01PDC and 01ICTserver; DNS is Active Directory Integrated on both servers.

    Originally we had bigger problems related to DNS entry inconsistencies between the two. Those have been sorted out (mostly, see below). What remains are a concerning dcdiag result and a strange dns problem.

    1. On each server, the dcdiag results for that server itself are fine. When we run with the /a switch to check each server from the other server, several tests fail with the error "The RPC server is unavailable." These include FrsEvent, DFSREvent and KccEvent.

    a) is this a concern?
    b) how do we correct it?

    I've been trolling around but haven't yet found anything that pointed me in the correct direction, although several of the posts I found helped me correct issues with the DNS earlier. (thanks!

    2. When we check on the 01ICTserver, all dns results are fine. However, when we check on the 01PDCserver, there is one very abnormal result. Checking just "01ictserver" gives the expected DNS result of the server's IP address, and nslookup indicates the correct suffix has been added to the request (as configured in the network card's IP4 settings). When querying "01ictserver.his.ac.zw" as the FQDN, we get a result indicating an extra ".ac.zw" has been added to the query and the answer is an _external_ IP address! This is not, of course, configured that way in our DNS server, so I'm mystified where it's coming from. I've already flushed the DNS cache and retried (and even rebooted, just to make sure) without any change in those results. (In case it's not clear, here is a screen capture:

    C:\Program Files>nslookup 01ICTserver
    Server: UnKnown
    Address: 192.168.2.3

    Name: 01ICTserver.his.ac.zw
    Address: 192.168.2.4


    C:\Program Files>nslookup 01ICTserver.his.ac.zw
    Server: UnKnown
    Address: 192.168.2.3

    Non-authoritative answer:
    Name: 01ICTserver.his.ac.zw.ac.zw
    Address: 67.215.65.132


    I don't know if the two problems are related, but we would appreciate any help you can provide.

  • #2
    Re: DCdiag errors, possible DNS related

    You shouldn't be adding/setting the DNS suffix on the NIC. For a DC (or any other domain joined computer) the DNS suffix is part of the full computer name (which can be seen on the Computer Name tab of System Properties).

    The DNS suffix on the NIC will be appended to the DNS suffix from the full computer name, so what seems to be happening is that every DNS query is appending the NIC configured DNS suffix along with the DNS suffix from the full computer name.

    Remove the DNS suffix from the NIC and see if that resolves the issue.

    Comment


    • #3
      Re: DCdiag errors, possible DNS related

      Thank you, JoeQwerty. I should have mentioned that neither server is configured with a dns suffix, both are configured to add the suffix if needed, but not parent suffixes. On 01pdc any other query we've tried is successful and we do not see the doubling of the domain. On 01ICTserver all results are normal. Only if we query on 01PDC for "01ICTserver.his.ac.zw" do we get the strange result.

      This entry isn't visible in the DNS console in our zones anywhere we can find, though the proper entry, with the internal address, is listed.

      Is there anywhere we can look in AD to see what entries have been stored for that server name? Maybe with ADSIedit?

      Or is the next step to remove the DNA server role from that server and, re-add it and rebuild the dns from scratch?

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