OSPF (Open Shortest Path First) has many configurable topologies. One of being the Stubby Area, as if that didn’t confuse you enough they introduced the Totally Stubby Area when this was first explain to me, I couldn’t grasp the concept of what the instructor was talking about, at least not until I drew the network out and configured it out in GNS3, it was then I was able to seen it for myself.
FYI OSPF overview, stubby networks only used for a small area that need to block all the external routes in their routing table. Routing will show a default internal route pointing to their ABR. Generally in the OSPF world all things must connect to Area 0, the ISP link would normally flow out Area 0 ASBR I think of Area 0 as the OSPF body and other area as limbs (the analogy works for me). Click topology for larger pic.