Network Load Balancing Event Messages

Applies To: Windows Server 2003 with SP1

Published: July 1, 2003

In This White Paper

This document contains a complete list of all Network Load Balancing (NLB) event messages, their causes, and detailed instructions for remedial actions, if any. The event severity and the format of each event are specified to aid the development of custom scripts.

The first section contains the events that are common for both Microsoft Windows Server 2000 and Microsoft Windows Server 2003 releases. The difference in the event formats and user actions between the two server versions is explained. The second section contains only those events that are new in Microsoft Windows Server 2003.


The event source reported for all of the messages described in this document will be WLBS.

About Alert Severity

Three levels of alert severity are indicated in Network Load Balancing event messages. Some events do not have an alert severity associated with them, and they are noted in this white paper.

  • E- Error. A significant problem, such as loss of data or loss of functionality. Administrator action will likely be required to correct the error.

  • W - Warning. An event that is not necessarily significant, but might indicate a possible future problem. Administrator action may or may not be required to correct the error.

  • I - For information only. An event that typically describes the successful operation of an application, driver, or service. Typically no administrator action is required.