Recipe 3.19 Finding the Global Catalog Servers in a Forest

3.19.1 Problem

You want a list of the global catalog servers in a forest.

3.19.2 Solution Using a graphical user interface
  1. Open LDP and from the menu select Connection Connect.

  2. For Server, enter the name of a DC.

  3. For Port, enter 389.

  4. Click OK.

  5. From the menu select Connection Bind.

  6. Enter credentials of a domain user.

  7. Click OK.

  8. From the menu select Browse Search.

  9. For BaseDN, type the DN of the Sites container (e.g., cn=sites,cn=configuration,dc=rallencorp, dc=com).

  10. For Scope, select Subtree.

  11. For Filter, enter (&(objectcategory=ntdsdsa)(options=1)).

  12. Click Run. Using a command-line interface
> dsquery server -forest -isgc Using VBScript
' This code prints the global catalog servers for the specified forest.
strForestName = "<ForestDNSName>"  ' e.g.
' ------ END CONFIGURATION ---------

set objRootDSE = GetObject("LDAP://" & strForestName & "/" & "RootDSE")
strADsPath = "<LDAP://" & objRootDSE.Get("configurationNamingContext") & ">;"
strFilter  = "(&(objectcategory=ntdsdsa)(options=1));"
strAttrs   = "distinguishedname;"
strScope   = "SubTree"

set objConn = CreateObject("ADODB.Connection")
objConn.Provider = "ADsDSOObject"
objConn.Open "Active Directory Provider"
set objRS = objConn.Execute(strADsPath & strFilter & strAttrs & strScope)
while not objRS.EOF
    set objNTDS = GetObject("LDAP://" & objRS.Fields(0).Value)
    set objServer = GetObject( objNTDS.Parent )
    Wscript.Echo objServer.Get("dNSHostName")

3.19.3 Discussion

To find the global catalog servers in a forest, you need to query for NTDS Settings objects that have the low-order bit of the options attribute equal to 1 under the sites container in the Configuration Naming Context. That attribute determines if a domain controller should be a global catalog server, but it does not necessarily mean it is a global catalog server yet. See Recipe 3.18 for more information on how to tell if a server marked as a global catalog is ready to accept requests as one.

Another option for locating global catalogs is DNS, which is described in Recipe 3.21.

3.19.4 See Also

Recipe 3.18 for determining if global catalog promotion is complete

    Chapter 3. Domain Controllers, Global Catalogs, and FSMOs
    Chapter 6. Users
    Appendix A. Tool List