Exchange 2010: Update the Global Address List(GAL)

You can use the Shell to update a global address list (GAL). A GAL is a directory that contains entries for every group, user, and contact within an organization's implementation of Microsoft Exchange.
1. Open the EMC Shell.
2. Run the following command:

Update-GlobalAddressList -Identity <GlobalAddressListIdParameter> –DomainController

* Note that this starts the process, but the completion could take 15 min. to a couplehours.

More Information:

Syntax:

update-GlobalAddressList -Identity <GlobalAddressListIdParameter> [-Confirm [<SwitchParameter>]] [-DomainController <Fqdn>] [-WhatIf [<SwitchParameter>]]

Identity = The Identity parameter specifies a unique identifier of the GAL being updated. These unique identifiers include the common name (CN), GUID, or distinguished name (DN).