Invalid ISTG value in AD Site and Services NTDS setting ?


Can anyone please assist me with how to fill in the correct server value in the ISTG field below screenshot:

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Senior IT System EngineerIT ProfessionalAsked:
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Will SzymkowskiSenior Solution ArchitectCommented:
Not sure what happened there but ISTG is selected by the KCC. You can manually modify this using ADSIEdit.msc
- Open ADSIEDIT.msc
- Expand Configuration
- Expand CN=Configuration,DC=domain,DC=com.
- Expand CN=Sites.
- Highlight CN=sitename
- Right-click on CN=NTDS Site Settings select, Properties
- Find the interSiteTopologyGenerator attribute
- This will list the current ISTG role holder
- Edit and then change the server name to a DC that is currently in that site

Senior IT System EngineerIT ProfessionalAuthor Commented:
Thanks for the suggestion Will.

When I compare the AD Sites and Services NTDS settings from:

The rest of Domain Controllers in the DataCentre AD site, the connection is showing as the screenshot above or unknown.

However, when I view it from the Domain Controller server in the affected AD site, it is showing as normal. (all fields are populated.)
SandeshdubeySenior Server EngineerCommented:
If you run repadmin /istg command in cmd what is the output can you post the same. You can try changing the value to correct server name from ADSIEdit. See this thread:

Also verify the health of DCs by dcdiag /q and repadmin /replsum. Check the directory service event log for any errors or warning.

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Senior IT System EngineerIT ProfessionalAuthor Commented:
Thanks !
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