In Exchange 2013, OAB is processed by mailbox server role which owns the copy of the database of the Arbitration system mailbox with OAB Persisted Capabilities.
OAB resides on the mailbox server in the folder “C:\Program Files\Microsoft\Exchange Server\V15\Client Access\OAB”.
This new feature, although extremely helpful for users, brought new challenges from the infrastructure and administration point of view.
We probably all know these blurry images appearing in Lync 2013 clients during the Lync call.
Remember, if you are looking at the Global Address List in Outlook then you are NOT looking at the Servers Global Address List*.