A. When you enable a domain controller (DC) as a GC, the DC can't start offering a GC service immediately. If you have multiple domains, the GC has to replicate information from another GC or for other domains before it can start functioning as a GC. By default, the new GC will wait at least 5 minutes before offering itself as a GC. You can check the Directory Service event log for event ID 1119, which confirms the server is now a GC.
If you want to automatically check the status of a new GC, you can create the following VBScript script on the DC:
Wscript.Echo "GC ready: " & objRootDSE.Get("isGlobalCatalogReady")
Save the code in a file called gcready.vbs. Then, to run the script, enter the command