Consider the following scenario:
- You have two Active Directory sites on a slow network in a Microsoft Exchange Server 2010 organization.
- You have an Exchange Server 2010 Client Access server and an Exchange Server 2010 Mailbox server in one Active Directory site.
- You have an Exchange Server 2010 Client Access server and add an Office Outlook user in the other Active Directory site.
- The user whose mailbox is located in the different Active Directory site tries to download the Exchange Offline Address Book (OAB).