RPC port range set on a clustered server

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at http://go.microsoft.com/fwlink/?linkid=34707.]  

Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry key to determine the value data for the ports: HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc\Internet\Ports

If the Exchange Server Analyzer finds that the following conditions are true, the Exchange Server Analyzer displays an error:

  • The HKLM\Software\Microsoft\Rpc\Internet\Ports key is present.

  • The server is a clustered Exchange server.

  • The server is having other errors.

When the registry key is present, Exchange Server is limited to a specific range of ports for RPC calls. If the Exchange server is under load and needs more ports than are currently available, errors may occur.

To correct this problem, you should add an additional 100 ports to the HKLM\Software\Microsoft\Rpc\Internet\Ports key until the problems go away.


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 the registry editor Regedt32.exe.


    To edit a REG_MULTI_SZ value, you must use Regedt32.exe instead of Regedit.exe.

  2. Navigate to: HKLM\Software\Microsoft\Rpc\Internet.

  3. In the right pane, double-click the Ports key. In the value box, increase the Port Range.

  4. Close the registry editor and restart the Exchange server.

Before you edit the registry, and for information about how to edit the registry, see Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows registry" (http://go.microsoft.com/fwlink/?linkid=3052&kbid=256986).

For more information about the HKLM\Software\Microsoft\Rpc\Internet registry keys, see the Microsoft Knowledge Base article 154596, "How to configure RPC dynamic port allocation to work with firewalls" (http://go.microsoft.com/fwlink/?linkid=3052&kbid=154596).