Q. When I run the Dcdiag diagnostics tool on a Windows Server 2003 domain controller (DC), I receive errors about the Intersite Topology Generator (ISTG). What's causing the errors?

A. When you run Dcdiag on a Windows 2003 DC with the /e (test all servers) switch, you might receive an error message similar to the following:

Running enterprise tests on: savilltech.comStarting test: IntersiteDoing intersite inbound replication test on site Gotham:*Warning: The next ISTG could not be authoritatively determined forsite Gotham. A DC should make an ISTG failover attempt in 63 minutes.*Warning: Current ISTG failed, ISTG role should be taken byVPC2003CLDDC in 1 hours and 3 minutes.

This error, which happens when your forest runs in Windows 2003 mode, occurs because the Windows 2003 forest mode uses a different ISTG method than Windows 2000 Server uses and Microsoft hasn't updated the Dcdiag tool to handle the newer method. Microsoft provides a hotfix that solves this problem. To obtain the hotfix, contact Microsoft Product Support Services (PSS) and mention to the Microsoft article "DCDiag.exe returns incorrect Intersite Topology Generator (ISTG) information," http://support.microsoft.com/?kbid=832628.