What is the purpose of OSPF virtual links?

The purpose of OSPF virtual links is to connect OSPF areas that are not directly connected to Area 0, which is the backbone area of OSPF. In a properly designed OSPF network, all areas should be interconnected with Area 0 to ensure efficient routing and proper OSPF operations. However, in scenarios where there is a disjointed OSPF network or when certain areas cannot physically connect to Area 0, a virtual link can be established.

A virtual link provides a logical connection between an area (typically a totally stubby area or a non-backbone area) and Area 0, allowing OSPF routers in that area to exchange routing information with the backbone area. This facilitates the necessary routing updates and keeps the entire OSPF routing table consistent across the network, as it ensures that all areas maintain a connection to the backbone area for efficient data routing.

While other options mention aspects of OSPF functionality, they do not accurately describe the specific role of virtual links, which is primarily to bridge areas and maintain OSPF's structural requirements for connectivity to Area 0.