Which Cisco IOS command enables OSPF on an interface in interface configuration mode?

The command that enables OSPF on an interface in interface configuration mode is indeed the correct choice. The command structure "ip ospf process-id area area-id" is specifically designed for this purpose.

In this command, "ip ospf" indicates that the OSPF routing process will be configured for the interface. The "process-id" is a unique identifier for the OSPF instance on the router, allowing the router to manage multiple OSPF processes if necessary. The "area area-id" specifies the area of the OSPF network to which this interface belongs. In OSPF, areas are used to optimize routing and limit the amount of routing information exchanged between routers, which is crucial for efficient network management.

When this command is issued in interface configuration mode, it directly assigns the specified interface to participate in the specified OSPF area, activating OSPF on that interface. This is a fundamental step in configuring OSPF on Cisco devices, allowing for dynamic routing based on OSPF protocols.

Other options do not fulfill the requirement of enabling OSPF on an interface directly. For instance, the command related to "router ospf process-id" is used to enter OSPF router configuration mode and