The correct answers are A and B .
The Network Security Support Engineer 7.6 Study Guide states under OSPF Troubleshooting :
“Follow these steps to troubleshoot an OSPF problem between two peers:
Check that the local router can reach the remote peer. IP addresses must be in the same subnet and have the same subnet mask.
Ensure that IP protocol 89 is not blocked.
Hello and dead intervals must match.
The OSPF router ID for each peer must be unique. Duplicate router IDs are not allowed.
Do the MTUs match?
If authentication is enabled, the type and password must match on both sides.”**
The same page also summarizes the troubleshooting tips as:
“Do peers have an IP address within the same subnet?”
“Is IP protocol 89 blocked?”
This directly confirms:
Why the other options are wrong:
C is wrong because TCP port 179 is used by BGP , not OSPF. OSPF uses IP protocol 89 , as the study guide explicitly notes
D is wrong because the study guide’s OSPF adjacency troubleshooting checklist does not require an active static route to the peer. OSPF neighbors form adjacency on directly reachable networks, and the guide instead focuses on same subnet, protocol 89, intervals, router ID, MTU, and authentication matching
So the verified answers are: A, B .
