Global address list not updating in exchange
Microsoft Outlook clients use a cached mode of the GAL, called an Offline Address Book that is synced with the GAL at a nearly daily interval.So, it can take multiple days before a change in on Enterprise level (Banner/My UI Info [formerly Nessie]) will propagate to be visible in Outlook.
All versions: check Download changes since last Send/Receive box.
This is called the Offline Address Book and is being generated on the Exchange server.
Due to various synching schedules, it can take up to 48 hours before you could actually see a change in Outlook after a modification has been made on the Exchange server or in Active Directory.
Information in the GAL is only updated once a day from AD.
AD service managers are responsible for the GAL data, though Exchange service managers have access as well.