What is a characteristic of a single-area OSPF network?

In a single-area OSPF (Open Shortest Path First) network, all routers operate within the same area, which is typically referred to as the backbone area or area 0. This means that the routing information is exchanged among all routers within that single area, allowing for efficient communication and routing decisions based on a consistent database of network topology.

Being in the backbone area helps optimize the OSPF protocol's performance because it minimizes the complexity of inter-area routing. All routers can maintain a synchronized view of the network, leading to quicker convergence times, reduced overhead, and simplified routing table management.

The other options touch on elements that do not apply specifically to a single-area OSPF network. For instance, while OSPF supports multiple routing paths and the ability to connect to external networks, these characteristics can exist in both single-area and multi-area configurations. However, a single-area OSPF network fundamentally relies on the presence of all routers in the same area, reinforcing why the backbone concept is so critical in this context. Additionally, handling multiple areas does not pertain to single-area configurations, as that would imply a more complex OSPF setup.