Q: What is automatic site coverage and how do I disable it?

A: Usually domain controllers (DCs) register site-specific records for their local site in DNS, enabling clients to easily find DCs and other services that are closest to them. If a site contains no DCs, then DCs in the sites closest to that site (calculated by site-link costs) will register site-specific records for that site as well, to help clients find a DC as close as possible. This is known as automatic site coverage.

With Windows Server 2008, your Windows Server 2003 DCs might have problems because they won’t see read-only DCs when they check for a DC. Therefore, the Windows 2003 DCs will register records for the site containing the read-only DCs, which isn’t desirable.

To disable automatic site coverage, perform the following steps on each of the DCs:

  1. Start the registry editor (regedit.exe).
  2. Navigate to the HKEY_ LOCAL_MACHINE\SYSTEM CurrentControlSet\Services Netlogon\Parameters registry subkey.
  3. From the Edit menu, select New, DWORD value.
  4. Enter a name of AutoSite- Coverage and press Enter.
  5. Double-click the new value and set it to 0 to disable it (1 enables it). Click OK.

—John Savill