DSAccess PreloadBaseDNs registry parameter is non-default
Topic Last Modified: 2009-09-17
The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine whether the search preloading functionality of Directory Service Access (DSAccess) has been changed from its default configuration:
The default value data for PreloadBaseDNs is:
'"' '"' '"' '"' '"'
If the Exchange Server Analyzer finds that the value for PreloadBaseDNs has been modified from these default values, a warning message is displayed. The Exchange Server Analyzer reports this configuration because it is a setting that should only be changed after consultation with Microsoft Product Support Services.
The DSAccess cache resides on the Exchange server and collects configuration and user records that are retrieved from the Active Directory® directory service. Records in the DSAccess cache are accessed by using an object's distinguished name, globally unique identifier (GUID), or a key constructed from the scope, BaseDN, and the search filter used to find the object in Active Directory. Subsequent accesses that use the same distinguished name, GUID, or key find the record in the cache. Therefore, unnecessary load on Active Directory is prevented for identical searches. However, DSAccess does not prevent load on Active Directory when the search filter is different from the search filter that is contained in the cache, even though DSAccess requests the same attribute set for the user object.
Search preloading is a means of avoiding the multiple Active Directory search problem that can occur when various search filters are issued on the same user object. Search preloading works by the previously mentioned key construction where a search entry is constructed by the scope, BaseDN, and the search filter.
For more information about configuring DSAccess search preloading, see the Microsoft Knowledge Base article 250572, "XCON: Preloading and the DSAccess Cache" (http://go.microsoft.com/fwlink/?LinkId=3052&kbid=250572).