Example: The values in the above screenshot mean OAB is generated once every day.The Exchange Server 2013 CAS role proxies the OAB download request to an appropriate Mailbox role server.Hence, current guidance is to plan organization mailbox placement such that you will have one organization mailbox active in an AD site.
An arbitration mailbox with Persisted Capability “Organization Capability OABGen” is responsible for OAB generation.
The CAS role maintains log of each request it handles in the log files, present in folder %Exchange Install Path%\Logging\Http Proxy\OAB\ These log files are an excellent tool to identify which mailbox server the CAS chose to serve the request.
Information of some important fields from the log file: The log file can be imported in Excel for better readability.
The Exchange team blog article OAB in Exchange Server 2013 introduced the new Offline Address Book (OAB) generation and distribution architecture in Exchange Server 2013.
Take a few moments to visit the article if you haven’t seen it yet or re-visit it for a quick refresher.