The correct commands to verify BFD session state are show bfd session, show bfd neighbors, and show bfd interface details. These three commands provide a complete operational picture: show bfd session delivers detailed timer and statistics information for each session, show bfd neighbors lists all BFD peers along with their current session states, and show bfd interface details reveals per-interface BFD configuration and state. On the Cisco CCNP ENARSI 300-410 exam, this topic tests your ability to troubleshoot BFD integration with routing protocols like OSPF and EIGRP, where verifying session liveness is critical for fast convergence. A common trap is confusing show bfd peer with show bfd neighbors—while both may exist on some platforms, the Cisco exam expects the standard show bfd neighbors output. Another pitfall is attempting show ip ospf bfd, which is invalid; instead, use show ip ospf interface to confirm BFD status under OSPF. Memory tip: think "S-N-I" for Session, Neighbors, Interface—the three essential verification views.
300-410 Bidirectional Forwarding Detection (BFD) Practice Question
This 300-410 practice question tests your understanding of bidirectional forwarding detection (bfd). Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which THREE commands can be used to verify the operational state of a BFD session? (Choose THREE.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
show bfd neighbors
The show bfd neighbors command displays all BFD neighbors and their session states. show bfd interface details shows BFD configuration and state per interface. show bfd session displays detailed session information including timers and statistics. show ip ospf bfd is not a valid command; the correct command is show ip ospf [interface] to see BFD status. show bfd peer is a valid command on some platforms but is less common; show bfd neighbors is preferred.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
show bfd neighbors
Why this is correct
Correct. This command lists all BFD neighbors and their current session state (Up, Down, etc.).
Incorrect. There is no such command. To verify BFD for OSPF, use show ip ospf interface or show bfd neighbors.
✗
show bfd peer
Why it's wrong here
Incorrect. While show bfd peer exists on some platforms (e.g., IOS-XR), the standard IOS command is show bfd neighbors.
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Trap categories for this question
Command / output trap
Incorrect. There is no such command. To verify BFD for OSPF, use show ip ospf interface or show bfd neighbors.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 300-410 OSPF questions on adjacency and route selection.
Bidirectional Forwarding Detection (BFD) — This question tests Bidirectional Forwarding Detection (BFD) — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: show bfd neighbors — The show bfd neighbors command displays all BFD neighbors and their session states. show bfd interface details shows BFD configuration and state per interface. show bfd session displays detailed session information including timers and statistics. show ip ospf bfd is not a valid command; the correct command is show ip ospf [interface] to see BFD status. show bfd peer is a valid command on some platforms but is less common; show bfd neighbors is preferred.
What should I do if I get this 300-410 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 300-410 OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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