AD Troubleshooting

AD and Domain-related issues and troubleshooting methods for Active Directory.

DCDIAG and the Not-N'sync Home Server

DCDIAG and the Not-N'sync Home Server

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A customer called in with questions about the following error she received in Dcdiag:

I ran DCDIAG /V /E /C and found these errors at the end of it:
 
Starting test: Intersite
         Doing intersite inbound replication test on site   Contoso-HQ-CHI:
            Locating & Contacting Intersite Topology Generator (ISTG) ...
               *** ERROR: The home server SRVDC02 is not in sync with
               CN=NTDS Settings\0ADEL:c6b655d5-c770-48af-b88c-4edfe3f2fbe8,CN=SRVDC04,CN=Servers,CN=Contoso-HQ-CHI,CN=Sites,CN=Configuration,DC=Contoso,DC=Local,
                unable to proceed. Suggest you run:
               dcdiag
               /s:CN=NTDS Settings\0ADEL:c6b655d5-c770-48af-b88c-4edfe3f2fbe8,CN=SRVDC04,CN=Servers,CN=Contoso-HQ-CHI,CN=Sites,CN=Configuration,DC=Contoso,DC=Local
               <options>
 
         Doing intersite inbound replication test on site    Contoso-Development-CHI:
            Locating & Contacting Intersite Topology Generator (ISTG) ...
               *** ERROR: The home server SRVDC02 is not in sync with
               CN=NTDS Settings\0ADEL:ce715b7e-ef94-444f-ac0e-d91193117cf3,CN=SRVDC03,CN=Servers,CN=Contoso-Development-CHI,CN=Sites,CN=Configuration,DC=Contoso,DC=Local,
                unable to proceed. Suggest you run:
               dcdiag
               /s:CN=NTDS Settings\0ADEL:ce715b7e-ef94-444f-ac0e-d91193117cf3,CN=SRVDC03,CN=Servers,CN=Contoso-Development-CHI,CN=Sites,CN=Configuration,DC=Contoso,DC=Local
               <options>
         Doing intersite inbound replication test on site Contoso-Tecnogen-CE:
            Locating & Contacting Intersite Topology Generator (ISTG) ...
               *** ERROR: The home server SRVDC02 is not in sync with
               CN=NTDS Settings\0ADEL:4c1cb178-d660-40ac-ae6e-5f9cf9946ea9,CN=SVRTGENDC01\0ADEL:f8922fd4-b7ea-4e66-a7b8-1a90d4ac80e7,CN=Servers,CN=Contoso-Tecnogen-CE,CN=Sites,CN=Configuration,DC=Contoso,DC=Local,
                unable to proceed. Suggest you run:
               dcdiag
               /s:CN=NTDS Settings\0ADEL:4c1cb178-d660-40ac-ae6e-5f9cf9946ea9,CN=SVRTGENDC01\0ADEL:f8922fd4-b7ea-4e66-a7b8-1a90d4ac80e7,CN=Servers,CN=Contoso-Tecnogen-CE,CN=Sites,CN=Configuration,DC=Contoso,DC=Local
               <options>
         Doing intersite inbound replication test on site Contoso-Biosint-LT:
            Locating & Contacting Intersite Topology Generator (ISTG) ...
               *** ERROR: The home server SRVDC02 is not in sync with
               CN=NTDS Settings\0ADEL:a633a171-e8f7-4db6-ad16-dd5855929c23,CN=SVRBIOSDC01\0ADEL:36b641f4-1484-47b2-9803-5aa1d6a41934,CN=Servers,CN=Contoso-Biosint-LT,CN=Sites,CN=Configuration,DC=Contoso,DC=Local,
                unable to proceed. Suggest you run:
               dcdiag
               /s:CN=NTDS Settings\0ADEL:a633a171-e8f7-4db6-ad16-dd5855929c23,CN=SVRBIOSDC01\0ADEL:36b641f4-1484-47b2-9803-5aa1d6a41934,CN=Servers,CN=Contoso-Biosint-LT,CN=Sites,CN=Configuration,DC=Contoso,DC=Local
               <options>
         Doing intersite inbound replication test on site
         Contoso-Financial-CHI:
            Locating & Contacting Intersite Topology Generator (ISTG) ...
               *** ERROR: The home server SRVDC02 is not in sync with
               CN=NTDS Settings\0ADEL:fe5196ae-26ff-4b68-b320-33b36d6fc057,CN=SRVDC05,CN=Servers,CN=Contoso-Financial-CHI,CN=Sites,CN=Configuration,DC=Contoso,DC=Local,
                unable to proceed. Suggest you run:
               dcdiag
               /s:CN=NTDS Settings\0ADEL:fe5196ae-26ff-4b68-b320-33b36d6fc057,CN=SRVDC05,CN=Servers,CN=Contoso-Financial-CHI,CN=Sites,CN=Configuration,DC=Contoso,DC=Local
               <options>

          Doing intersite inbound replication test on site Contoso-CHI:
            Locating & Contacting Intersite Topology Generator (ISTG) ...
               The ISTG for site SigmaTau-CHI is: ADSRVDC02.
            Checking for down bridgeheads ...
               Bridghead Contoso-Research-NY\SVRBFPDC02 is up and replicating fine.
               Bridghead Contoso-CHI\ADSRVDC02 is up and replicating fine.
            Doing in depth site analysis ...
               All expected sites and bridgeheads are replicating into site
               Contoso-CHI.
         ......................... Contoso.Local failed test Intersite

 
I would like to eliminate the errors and confirm that AD is working fine.

Customer had demoted and then rapidly promoted again the DC02 server.

When you demote a DC the NTDS connection objects for it aren’t removed immediately, it can in some cases take up to 14 days for them to be removed automatically.

The tell-tale sign of this being the problem in this case is the DEL+GUID part of the output – this is simply an old NTDS connection object related to the demoted DC that still hasn’t been removed by the KCC and is expected behavior after demoting a DC.

 

Comments
  • OK, how do you remove that object?

  • You can either locate it using ADSIEdit.msc and delete it manually or wait for the KCC to delete it.

    I.e. this is a cosmetic issue and is expected behaviour after demoting a DC.

    The KCC typically cleans this itself out when it performs garbage collection - garbage collection may however be delayed on a DC if it is busy with other things.

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