ospf scenario
Highest IP address ABR routes convert the type7 into type 5.
Default route is not generated by default in area nssa unless "are nssa <> default originate " configured.
Totally stubby NSSA area generate the default route by default.
DR/BDR does not support the preempt therefore if DR fails BDR will become DR new BDR will be connected. DR does not become DR even when it is high priority.
With "ip ospf priority 0" router does not participate in DR/BDR.
OSPF behaves as distance vector protocol when multiple area in use.
Highest priority/IP address becomes the DR/BDR.
OSPF hellos are always send from primary interface.