I've attached a diagram for something that I ran into this morning. I have 2 ospf areas, one of which is an nssa, and I have a RIP router behind the nssa. I noticed that the same route that RouterB seen as an N2 route, RouterA sees as an E2 route. Is this because the ASBR is converting Type-7 LSA into a Type-5, and then RouterA is receiving the Type-5 LSA marking it as an external route, but not necessarily known that it came from an NSSA?
To reiterate, Router A is not part of the NSSA so it will receive external routes as E1 or E2.
Router C is part of the NSSA (Area 1), so any external routes from a ASBR on that area (on this case router B) will be seen as N1 or N2.