Cisco CCNA mock exam questions sample test – Question 259

.Examine the partial output from two adjacent routers:
Which of the following statements describes why the two routers are NOT forming an OSPF neighbor adjacency?

A. The process IDs do not match
B. The router IDs are misconfigured
C. The distance is misconfigured
D. The reference bandwidth does not match

Correct Answer: B

The output shows that the router IDs for RTR78 and RTR79 are the same value, which should not be the case. One of the two routers has been misconfigured with the other router’s
ID. This will prevent an OSPF neighbor adjacency from forming.
Other issues can that can prevent an adjacency are:
Mismatched OSPF area number
Mismatched OSPF area type
Mismatched subnet and subnet mask
Mismatched OSPF HELLO and dead timer values
The process IDs do not have to match. It does not matter whether they match or do not match because the process ID is only locally significant on the device.
The administrative distance is not misconfigured in the output. Both routers are using the default OSPF administrative distance of 110.
If the reference bandwidths do not match, it will affect the calculation of the path cost, but it will not prevent an adjacency from forming.
Routing Fundamentals
Configure, verify, and troubleshoot single area and multi-area OSPFv2 for IPv4 (excluding authentication, filtering, manual summarization, redistribution, stub, virtual-link, and LSAs)
Support > Technology Support > IP > IP Routing > Troubleshoot and Alerts > Troubleshooting TechNotes > OSPF Neighbor Problems Explained