AD Forest Recovery - Adding the GC

Applies to: Windows Server 2022, Windows Server 2019, Windows Server 2016, Windows Server 2012 and 2012 R2, Windows Server 2008 and 2008 R2

Use the following procedure to add the global catalog to a DC.

To add the global catalog

  1. Click Start, point to All Programs, point to Administrative Tools, and then click Active Directory Sites and Services.
  2. In the console tree, expand the Sites container, and then select the appropriate site that contains the target server.
  3. Expand the Servers container, and then expand the server object for the DC to which you want to add the global catalog.
  4. Right-click NTDS Settings, and then click Properties.
  5. Select the Global Catalog check box. Add GC

To add the global catalog using Repadmin

  • Open an elevated command prompt, type the following command, and press ENTER:

    repadmin.exe /options DC_NAME +IS_GC

The following are ways to speed up the process of adding the global catalog to the DC in the root domain:

  • Ideally, the DC in the root domain should be a replication partner of the restored DCs in the non-root domains. If so, confirm that the Knowledge Consistency Checker (KCC) has created the corresponding repsFrom object for the source DC and partition in the root DC. You can confirm this by running the repadmin /showreps /v command.

  • If there is no repsFrom object created, create this object for the configuration partition. This way, the DC in the root domain can determine which DCs in the non-root domain have been deleted. You can do this with the following commands:

    repadmin /add ConfigurationNamingContext DestinationDomainController SourceDomainControllerCNAME
    repadmin /options DSA -Disable_NTDSCONN_XLATE

    The format for the SourceDomainControllerCNAME is:

    sourceDCGuid._msdcs.root domain

    For example, the repadmin /add command for the configuration partition of the domain could be:

    repadmin /add cn=configuration,DC=contoso,DC=com DC01
  • If the repsFrom object is present, try to sync the DC in the root domain with the DC in the non-root domain as follows:

    Repadmin /sync DomainNamingContext DestinationDomainController SourceDomainControllerGUID

    Where DestinationDomainController is the DC in the root domain and SourceDomainController is the restored DC in the non-root domain.

  • The root domain DNS server should have the alias (CNAME) resource records for the source DC. Ensure that the parent DNS zone contains delegation resource records (name server (NS) and host (A) resource records) for the correct DCs (the DCs that have been restored from backup) in the child zone.

  • Make sure that the DC in the root domain is contacting the correct Key Distribution Center (KDC) in the non-root domain. To test this, at the command prompt, type the following command, and then press ENTER:

    nltest /dsgetdc:nonroot domain name /KDC /Force

Next Steps