ABR - Area Border Router - Router that has interfaces attached to multiple areas.
Area Zero - Backbone area where all other OSPF areas connect (also referred to as Area 0.0.0.0).
ASBR - Autonomous System Boundary Router - Router that has at least one
interface attached to an external network.
DR - Designated Router
IA Routes - Inter-Area Routes
LSA - Link State Advertisement
NSSA - Not-so-stubby Area (See Area Types below)
TSA - Totally Stubby Area (See Area Types below)
Backbone Area - Primary OSPF area where inter-area routing occurs.
Not-So-Stubby Area
Stub Area - OSPF area that can receive inter-area routes, and does not accept external routes.
Totally Stubby Area - Cisco-specific , area which only receives inter-area routes, and does not allow external and summary routes.
With OSPF route metrics, the lower the value, the higher the priority.