In single-area OSPF, what can be said about the routers?

In a single-area OSPF configuration, all routers are part of the same area, which is typically the backbone area, designated as Area 0. This structure is essential for OSPF's operation because it simplifies the routing process, allowing OSPF to maintain a single link-state database that every router in that area shares. This shared database enables efficient path calculation and eventual route distribution across the routers.

By operating exclusively within a single area, these routers can communicate directly with each other without the need to manage multiple areas, which would complicate the OSPF topology and may lead to additional overhead in managing link-state advertisements. Therefore, stating that all routers belong to the backbone area reflects accurately the uniform structure and efficient operation of OSPF in a single-area scenario.