In which area type did an OSPF Type 7 LSA originate?

An OSPF Type 7 LSA, also known as a NSSA (Not-Stubby Area) LSA, is specifically used within a Not-So-Stubby Area. This type of LSA is designed to allow external routes to be introduced into an NSSA while still maintaining the characteristics that distinguish it from standard areas. Inside an NSSA, Type 7 LSAs can be generated by ASBRs (Autonomous System Boundary Routers) to carry external network information from other routing protocols or from external OSPF areas.

The significance of Type 7 LSAs is that they can be translated into Type 5 LSAs when they reach the OSPF backbone area or a standard OSPF area. This translation allows the external routes to be redistributed while preserving the integrity of routing information within the OSPF domain.

Understanding that Type 7 LSAs are meant specifically for NSSAs highlights their purpose in OSPF's architecture, where they facilitate external route advertisement without compromising the structure of stubby areas. Other area types, like the Backbone, Stub, or Totally Stubby areas, do not utilize Type 7 LSAs for routing information exchange.