How to connect AD Explorer from Sysinternals to Global Catalog
While ADSI Edit is not as fancy as ADexplorer, it can work for your scenario.
Open ADSIEdit, right-click, and choose “Connect to.” In the Connections Settings, click the “Advanced” button and change from “LDAP” to “Global Catalog.” This will cause your connection to use port 3268 when you connect to your target server.
The "Path" in the connect to screen should've changed from LDAP//...... to GC://
If you wish, you can specify a server to connect to and fill in the Distinguished name or Naming context with something like: DC=mydomain,DC=local and under the computer node leave the defaults.