To test whether a domain controller is also a global catalog server:
1. Click Start, point to Programs, point to Administrative Tools, and then click Active Directory Sites and Services.
2. Double-click Sites in the left pane, and then locate the appropriate site or click Default-first-site-name if no other sites are available.
3. Open the Servers folder, and then click the domain controller.
4. In the domain controller's folder, double-click NTDS Settings.
5. On the Action menu, click Properties.
6. On the General tab, view the Global Catalog check box to see if it is selected.