Recipe 11.25 Finding the ISTG for a Site

11.25.1 Problem

You want to find the Inter-Site Topology Generator (ISTG) for a site.

11.25.2 Solution

11.25.2.1 Using a graphical user interface

Open the Active Directory Sites and Services snap-in.
Click on the site you are interested in.
In the right pane, double-click on the NTDS Site Settings object.
The ISTG will be displayed under Inter-Site Topology Generator if one is present.

11.25.2.2 Using a command-line interface

> repadmin /istg <DomainControllerName>

This command is available only with the Windows Server 2003 version of repadmin.

11.25.2.3 Using VBScript

' This code finds the ISTG for the specified site.
' ------ SCRIPT CONFIGURATION ------
strSiteName = <SiteName>  ' e.g. Raleigh
' ------ END CONFIGURATION ---------

set objRootDSE = GetObject("LDAP://RootDSE")
set objSiteSettings = GetObject("LDAP://cn=NTDS Site Settings,cn=" & _
                                strSiteName & ",cn=sites," & _
                                objRootDSE.Get("ConfigurationNamingContext"))
on error resume next
strISTGDN = objSiteSettings.Get("interSiteTopologyGenerator")
if (strISTGDN <> "") then
   set objNTDSSettings = GetObject("LDAP://" & strISTGDN)
   set objServer = GetObject( objNTDSSettings.Parent )
   WScript.Echo "ISTG for site " & strSiteName & " is " & _
                objServer.Get("dnsHostName")
else
   WScript.Echo "No ISTG found for site " & strSiteName
end if

11.25.3 Discussion

One domain controller in every site is picked as the ISTG for that site. While each domain controller is responsible for creating its own intra-site connection objects, the ISTG for a site is responsible for creating the inter-site connection objects for the bridgehead servers in the site.

The current ISTG for a site is stored in the interSiteTopologyGenerator attribute of the site's NTDS Site Settings object. The distinguished name of ISTG's NTDS Settings object is stored in the interSiteTopologyGenerator attribute.

Disabling inter-site topology generation is synonymous with disabling the KCC for a site. See Recipe 11.29 for more information on disabling the KCC.

11.25.4 See Also

Recipe 11.26 for moving the ISTG, MS KB 224815 (The Role of the Inter-Site Topology Generator in Active Directory Replication), and MS KB 224599 (Determining the Inter-Site Topology Generator (ISTG) of a Site in the Active Directory)