Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool queries the Active Directory® directory service to determine whether the heuristics attribute has been configured to suppress user version changes of the link state information. By default, the heuristics attribute is not configured. If the Exchange Server Analyzer finds that the heuristics attribute is set to 2048, the Exchange Server Analyzer displays a non-default configuration message.

Link state tables are used to guarantee efficient and reliable message routing. The link state table contains version information for each routing group in the form of major, minor, and user version numbers. Major version changes have highest priority, followed by minor changes, and finally changes to user version numbers.

User version changes occur when there is a base-level directory service update. These minimal changes include routing group master changes, when services are started or stopped on an Exchange server, when another server is added to the routing group, or when a member server loses connectivity to the routing group master.

A base-level directory service update may occur when an Exchange Server administrator changes something at the routing group level. For example, a user version change occurs when an administrator changes a routing group name, adds a server, or removes a server. However, the primary cause of user version changes is the Microsoft Windows® Management Instrumentation (WMI) data that is in each server. This data states which services are running. If you stop and start a service, user version changes in the link state table are replicated to all Exchange Server computers in the organization.

Frequent user version updates could create an unwanted amount of network traffic and can be suppressed by first obtaining a hotfix from Microsoft Product Support Services and then setting the heuristics attribute to 2048 (0x800 in hexadecimal).

If user version updates are not generating excessive network traffic, it is recommended that you do not suppress them.

To revert to the default configuration
  1. Open Active Directory Service Interfaces (ADSI) Edit.

  2. In ADSI Edit, expand Configuration Container, expand CN=Configuration, DC=DomainName, DC=com, expand CN=Services, and then expand CN=Microsoft Exchange.

  3. Right-click CN=OrganizationName, and then click Properties.

  4. In the Select a property to view box, click Heuristics.

  5. In Edit Attribute box, clear the value 0x800.

  6. Click Set, and then click OK.

  7. Close ADSI Edit.

If you incorrectly modify the attributes of Active Directory objects when you use ADSI Edit, the LDP (ldp.exe) tool, or another Lightweight Directory Access Protocol (LDAP) version 3 client, you may cause serious problems. These problems may require that you reinstall Microsoft Windows Server™ 2003, Exchange Server 2003, or both. Modify Active Directory object attributes at your own risk.

For more information about link state and user version numbers, see "Link State Propagation" in the Technical Reference Guide for Exchange Server 2003 (