This 350-401 practice question tests your understanding of infrastructure security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A network engineer runs the following command on Router R1:
R1# show ip bgp summary
BGP router identifier 10.0.0.1, local AS number 65001
BGP table version is 10, main routing table version 10
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
192.168.1.2 4 65002 1024 1020 10 0 0 02:30:15 5
192.168.1.3 4 65003 500 498 10 0 0 00:15:20 3
10.0.0.2 4 65004 0 0 0 0 0 never Active
Based on this output, what can be concluded?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "never"
Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The BGP session to 10.0.0.2 is down due to a TCP connection issue.
The output shows BGP neighbors. The first two neighbors are established (up/down time and prefixes received). The third neighbor (10.0.0.2) is in Active state, meaning it is trying to establish a TCP connection but failing. This could be due to a missing route, ACL blocking, or incorrect configuration.
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.
✗
All BGP neighbors are fully established.
Why it's wrong here
The third neighbor is in Active state, not established.
✓
The BGP session to 10.0.0.2 is down due to a TCP connection issue.
Why this is correct
The Active state indicates the router is trying to open a TCP connection but has not succeeded.
Clue confirmation
The clue word "never" in the question point toward this answer.
The BGP session to 192.168.1.3 has been up for 2 hours 30 minutes.
Why it's wrong here
The up/down time for 192.168.1.3 is 00:15:20, not 2:30:15.
✗
The router is receiving prefixes from all neighbors.
Why it's wrong here
The third neighbor has 0 prefixes received because the session is not established.
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.
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 350-401 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 350-401 OSPF questions on adjacency and route selection.
Infrastructure Security — This question tests Infrastructure Security — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: The BGP session to 10.0.0.2 is down due to a TCP connection issue. — The output shows BGP neighbors. The first two neighbors are established (up/down time and prefixes received). The third neighbor (10.0.0.2) is in Active state, meaning it is trying to establish a TCP connection but failing. This could be due to a missing route, ACL blocking, or incorrect configuration.
What should I do if I get this 350-401 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 350-401 OSPF questions on adjacency and route selection.
Are there clue words in this question I should notice?
Yes — watch for: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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