You want to determine if a domain controller is a global catalog server. After you initially enable the global catalog on a domain controller, it can take some time for all of the read-only naming contexts to replicate to it, depending on how large your forest is.
isGlobalCatalogReady attribute on the
RootDSE for the domain controller. A TRUE value
means the server is a global catalog and a FALSE value indicates it
For more information on how to query the
see Recipe 4.1.
Once a server has completed initial replication of the global
isGlobalCatalogReady attribute in the
RootDSE will be marked TRUE. Another way to determine if a domain
controller has been at least flagged to become a global catalog is by
checking if the
options attribute on the
nTDSDSA object for the server has been set to 1.
Note that this does not necessarily mean the server is accepting
requests as a global catalog. An additional query to the
RootDSE as described in the Solution, or directly
to port 3268 (the global catalog port)
could confirm it.
Recipe 4.1 for viewing the RootDSE