Hi We are running Exchange 2007 SP1 and AD 2003. All our Exchange servers are located in HQ. We also have a GC/DC in Branch1 which has about 200 users. All users connect via Outlook 2007 and are set to cached Exchange mode. From what I understand, there is a process named DSProxy that Exchange uses to refer Outlook to a GC that is in the same site as the Exchange mailbox server. From then on, Outlook uses this GC for address lookups etc. At the same time, I understand that when Outlook is in cached Exchange mode, it uses the Offline Address Book (OAB) for address book functionality. The OAB is held on a Public Folder. So, my question is, if Outlook is set to cached mode and uses the OAB, then why does it still need to contact a GC directly? From what I can recall, if I check the connection status of Outlook when in cached mode, I can still see GC's listed for directory access? Secondly, if there is a need for Outlook to access a GC directly, is it possible to make a change on Exchange so that Outlook uses a local GC, not the one in the same site as Exchange?

Hi,See Amit's Comments herehttp://social.technet.microsoft.com/Forums/en-US/exchangesvrgeneral/thread/740be8e8-8fab-4af4-83ab-fbbf09cfa54eHopes this answers your query.Raj

Q: “If Outlook is set to cached mode and uses the OAB, then why does it still need to contact a GC directly? From what I can recall, if I check the connection status of Outlook when in cached mode, I can still see GC's listed for directory access?” A: Per my knowledge, in reality, OAB has its synchronization interval. You can’t resolve the object (Mailbox, contact or DL) by querying the local OAB only in the real-time. That’s why the clients need to GC to access the address book and other directory information, and build OAB as the alternative way Client and Server Details Q: “if there is a need for Outlook to access a GC directly, is it possible to make a change on Exchange so that Outlook uses a local GC, not the one in the same site as Exchange?” A: You can use “Set-ExchangeServer” cmdlet with “StaticGlobalCatalogs” parameter to do it, but it’s it is not optimal from the perspective of ongoing management. “You have to remember which GCs belong to whom and manually tune and maintain lists instead of letting Exchange automatically optimize the load balancing” (Reference) How to configure Outlook to a specific global catalog server or to the closest global catalog server How to query the DC/GC that are used by exchange serversJames Luo TechNet Subscriber Support (http://technet.microsoft.com/en-us/subscriptions/ms788697.aspx) If you have any feedback on our support, please contact tngfb@microsoft.com