Topic Last Modified: 2006-10-02

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine whether Media Sense Detection is configured correctly:


The Exchange Server Analyzer also examines the following registry entry to determine the version of Windows that is running on the destination computer:

HKLM\Software\Microsoft\Windows NT\CurrentVersion\CurrentVersion

A CurrentVersion value of 4.0 indicates the computer is running Microsoft Windows NT® Server 4.0. A value of 5.0 indicates the computer is running a Windows® 2000 Server operating system, and a value of 5.2 indicates the computer is running a Windows Server™ 2003 operating system.

Additionally, the Exchange Server Analyzer queries the Win32_Service Microsoft Windows Management Instrumentation (WMI) class to determine the value of the Started key for ClusSvc, the Microsoft Windows Cluster service. A value of True indicates the Windows Cluster service is running, and a value of False indicates it is not running.

If the Exchange Server Analyzer finds that the Windows Cluster service is running on Windows Server 2003, Enterprise Edition or Windows Server 2003, Datacenter Edition and the value for the DisableDHCPMediaSense registry key is set to 1, a warning is displayed.

When you use the Windows Server 2003 Cluster service, if network connectivity is lost, the TCP/IP stack does not get unloaded by default, as it did in Windows 2000 Server. As a result, you are no longer required to set the DisableDHCPMediaSense registry key. In Windows 2000 Server, if network connectivity is lost, the TCP/IP stack was unloaded, which meant that all cluster resources, including resources in an Exchange Virtual Server, that depended on IP addresses were taken offline. When the networks came back online, their network role reverted to the default setting (that is, client and private). By disabling Media Sense by default, it means the network role is preserved, as well as keeping all IP address-dependant resources online.

  This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore the registry if a problem occurs. For information about how to restore the registry, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.

To correct this warning

  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to:


  3. In the right pane, right-click to modify (set to 0 to disable) or delete the DisableDHCPMediaSense registry value.

  4. Close the registry editor.

  5. Move all cluster resources to another node, or take them offline. Then, restart the cluster node for the change to take effect.

  6. Repeat this process on all other nodes in the cluster that generated this warning.

For more information about the Microsoft Windows registry, see the Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows Registry" (

For more information about Media Sense Detection and Windows clusters, see the following Knowledge Base articles: