Exchange 2010 Enterprise SP2. 2 Member DAG. A/P working just fine.
Currently the OAB Generation Server is Node001. When I take Node001 down for service or an unplanned outage. Should I also setup an new OAB on Node002 too as well?
That's usually not neccassery, the OAB will still be available for download while the OAB generation server is down. Unless you have many changes in the directory during the downtime, but this is not a common task.