How is a passive OSPF interface characterized?

A passive OSPF interface is characterized as one that does not send hello messages. In OSPF (Open Shortest Path First), hello messages are crucial for establishing and maintaining neighbor relationships between OSPF routers. When an interface is configured as passive, it will not participate in the OSPF neighbor discovery process; this means it will not send or receive these hello packets.

This configuration is particularly useful for interfaces where you do not want to form OSPF adjacencies, such as on point-to-point links or on interfaces connected to end hosts. By setting an interface to passive, you can effectively include the network in OSPF routing without the overhead of neighbor formation, while still allowing OSPF to route traffic based on the known routes. This enhances network stability and reduces unnecessary OSPF traffic on these interfaces.

Other choices might refer to interfaces that either send OSPF messages or are non-configured, which do not represent the characteristics of a passive interface.