strComputer = "Ordinateur"

Const NTDSDSA_OPT_IS_GC = 1

Set objRootDSE = GetObject("LDAP://" & strComputer & "/rootDSE")
strDsServiceDN = objRootDSE.Get("dsServiceName")
Set objDsRoot = GetObject("LDAP://" & strComputer & "/" & strDsServiceDN)
intOptions = objDsRoot.Get("options")

If intOptions And NTDSDSA_OPT_IS_GC Then
      WScript.Echo strComputer & " is a global catalog server."
Else
      Wscript.Echo strComputer & " is not a global catalog server."
End If