In Exchange 2013, this is the flow of OAB download: This new workflow overcomes the disadvantages of legacy OAB download workflow.
The Organization Mailbox is a new type of arbitration mailbox introduced with Exchange 2013.
In Exchange 2013, the OAB is generated by each Exchange 2013 Mailbox server(s) that hosts a special type of arbitration mailbox, called parameter anymore.
OAB in Exchange Server 2013: Get-Offline Address Book “Default Offline Address Book (Ex2012)” | fl name,server Name : Default Offline Address Book (Ex2012) Server : The unbinding of OAB from a specific server allows the same OAB to be generated by multiple Mailbox servers. OAB generation would start at the scheduled time configured on the OAB property, irrespective of the work load on the server.
You need to be assigned permissions before you can run this cmdlet.