How to configure Outlook to a specific global catalog server or to the closest global catalog server

In some situations, you may notice excessive network traffic when Microsoft Outlook attempts to contact the global catalog server.

This article describes how to configure Outlook to a specific global catalog server or to the closest global catalog server.

Note If the global catalog server and the Exchange Server computer are in the same site as the Outlook client, you do not need to make this registry setting. The normal referral mechanism provides the best performance.

This behavior occurs when the Exchange Server computer (where the Outlook client is homed) and the global catalog server are both located in a site that is remote from the Outlook client location.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

How to set the closest global catalog server

Use the following steps to force Outlook to identify and use the closest global catalog server.

1. Click Start, and then click Run.
2. In the Open box, type regedit.exe, and then click OK.
3. Locate and then click the following key in the registry:
   HKEY_CURRENT_USER\Software\Microsoft\Exchange\Exchange Provider
   Note You may have to create the registry path.
   
   
4. On the Edit menu, click Add Value, and then add the following registry value:
   Value name: Closest GC
   Data type: REG_DWORD
   Radix: Hexadecimal
   Value data: 0x00000001
5. Quit Registry Editor.

How to set a specific global catalog server

In other topologies, you may want to force Outlook to communicate with a specific global catalog server, not necessarily the global catalog server that is closest to the Outlook client.

Note that although you can manually change the registry parameter in the MAPI profile, it is overwritten the next time that you start Outlook.

To force Outlook to use a pre-defined global catalog server, use the following steps to set the following special registry parameter to point to the Fully Qualified Domain Name (FQDN). Doing this over-rides any setting in the MAPI profile.

1. Click Start, and then click Run.
2. In the Open box, type regedit.exe, and then click OK.
3. Locate and then click the following key in the registry:
   HKEY_CURRENT_USER\Software\Microsoft\Exchange\Exchange Provider
   
   Note You may have to create the registry path.
4. On the Edit menu, click Add Value, and then add the following registry value:
   Value name: DS Server
   Data type: REG_SZ (string)
   Value data: FQDN of the global catalog server
5. Quit Registry Editor. If Outlook stops responding after you set the closest global catalog server or set a specific global catalog server, Outlook returns to the DSProxy process on the Exchange 2000 server and requests a new referral. The following are two possible limitations if you configure Outlook to a specific global catalog server:

• The client-detected global catalog server may be out of date or semi-functional. If the global catalog server is having problems but still responds to Named Service Provider Interface (NSPI) requests, Outlook may not stop responding, and Outlook may return to the DSProxy for a new referral.
• In multidomain environments, the global catalog server that you select may not be in the same domain as group objects in the Active Directory directory service. Therefore, users cannot update group membership because the local global catalog server has a read-only copy of the group.
  
  This behavior can also affect how you add delegate permissions to a third party's account.
  
  This behavior was recently changed so that you receive an error message when the "Send on Behalf Of" permission is not written. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
  913807  (http://support.microsoft.com/kb/913807/ ) Description of the update for Outlook 2003: March 14, 2006

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

The information in this article was derived from the "Understanding and Troubleshooting Directory Access" white paper. To view this white paper, visit the following Microsoft Web site: