Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine if 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 target computer:

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

A CurrentVersion value of 4.0 indicates that the computer is running Microsoft Windows NT® Server 4.0. A value of 5.0 indicates the computer is running a Microsoft Windows® 2000 Server operating system, and a value of 5.2 indicates the computer is running a Microsoft 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 2000 Advanced Server or Windows 2000 Datacenter Server and if the DisableDHCPMediaSense registry key is present and the value is not set to 1, a warning is displayed.

When using the Windows 2000 Server Cluster service, if network connectivity is lost, the TCP/IP stack is unloaded. This means 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 (client and private). To prevent this from happening, it is recommended that you disable Media Sense Detection on all Windows 2000 Server-based clusters. Media Sense Detection is automatically disabled on Windows Server 2003-based clusters.

  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. Right-click Parameters, and then click New | DWORD value. Type DisableDHCPMediaSense for the name and press Enter.

  4. In the right pane, double-click DisableDHCPMediaSense and enter a Value data of 1.

  5. Close the registry editor.

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

  7. Repeat this process on all 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: