CCNA: Cisco Certified Network Associate — Question 280

If all OSPF routers in a single area are configured with the same priority value, what value does a router use for the OSPF router ID in the absence of a loopback interface?

Answer options

• A. the IP address of the first Fast Ethernet interface
• B. the IP address of the console management interface
• C. the highest IP address among its active interfaces
• D. the lowest IP address among its active interfaces
• E. the priority value until a loopback interface is configured

Correct answer: C

Explanation

The correct answer is C because, in the absence of a loopback interface, OSPF will choose the highest IP address among the active interfaces as the router ID. Options A and B are incorrect as they specify specific interfaces that may not be the highest. Option D incorrectly refers to the lowest IP address, which is not used for the router ID in this scenario, and option E is not applicable since a valid router ID must be selected regardless of the priority value.