Query-Based Distribution Groups Described
A query-based distribution group provides the same functionality as a standard distribution group. However, instead of specifying static user memberships, you can use an LDAP query (for example, "All full-time employees in my company") to dynamically build membership in a query-based distribution group. This reduces administrative costs because of the dynamic nature of the distribution group. However, query-based distribution groups have a higher performance cost for queries whose outcome produces many results. This cost is in terms of server resources, such as high CPU usage and increased memory usage. This increased usage occurs because every time an e-mail message is sent to a query-based distribution group, an LDAP query is executed against Active Directory to determine its membership.
Important
You cannot view the membership of a query-based distribution group in the GAL because it is dynamically generated every time mail is sent.
Query-based distribution groups work reliably in the following topologies:
Exchange 2003-only environment (no Exchange servers prior to Exchange 2003) running in native mode.
Exchange 2000 Service Pack 3 (SP3) and Exchange 2003 in native mode. If you have Windows 2000 global catalog servers in this scenario, you can modify a registry key on the Exchange 2000 SP3 servers to increase reliability. This modification is covered in the next section.
If you are running versions of Exchange prior to Exchange 2000 SP3 in your environment, query-based distribution groups will not work reliably.