Question 1mediumdrag order
Review the full OSPF breakdown →Question 1,380 of 2,015
Quick Answer
The correct order for OSPF virtual link configuration steps begins with confirming backbone route reachability, as this foundational step ensures the transit area has full connectivity and at least one ABR before proceeding. This sequence is critical because a virtual link is essentially a logical tunnel across a non-backbone area to connect a disconnected area to area 0, and without verifying that the transit area is fully operational and that the two ABRs can already communicate, the virtual link will fail to form. On the ENCOR 350-401 exam, this drag-and-drop question tests your understanding that OSPF virtual links are a last-resort design fix, not a routine configuration, and a common trap is placing the verification step before the configuration command. Remember the mnemonic "CRV-C" for the order: Confirm reachability, identify Router IDs, configure the Virtual link, then Verify with 'show ip ospf virtual-links', and finally Confirm routes are learned across the link.
CCNP OSPF Practice Question
This 350-401 practice question tests your understanding of ospf. 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.
Drag and drop the steps of OSPF virtual link configuration across area 0 into the correct order, from first to last.
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"first"Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Ensure transit area has full connectivity
First, ensure the transit area (non-backbone) has full connectivity and at least one ABR. Then, identify the router IDs of the two ABRs that will form the virtual link. On each ABR, configure the virtual link using the 'area transit-area-id virtual-link router-id' command. Verify the virtual link state using 'show ip ospf virtual-links'. Finally, confirm that routes from the backbone area are now reachable across the virtual link.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
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.
What to study next
Got this wrong? Here's your next step.
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.
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FAQ
Questions learners often ask
What does this 350-401 question test?
OSPF — This question tests OSPF — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: Ensure transit area has full connectivity — First, ensure the transit area (non-backbone) has full connectivity and at least one ABR. Then, identify the router IDs of the two ABRs that will form the virtual link. On each ABR, configure the virtual link using the 'area transit-area-id virtual-link router-id' command. Verify the virtual link state using 'show ip ospf virtual-links'. Finally, confirm that routes from the backbone area are now reachable across the virtual link.
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: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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Same concept, more angles
1 more ways this is tested on 350-401
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Drag and drop the steps of OSPF virtual link configuration across area 0 into the correct order, from first to last.
hard- ✓ A.Identify ABRs and transit area (not area 0)
- ✓ B.Configure virtual-link on first ABR
- ✓ C.Configure virtual-link on second ABR
- ✓ D.Ensure OSPF adjacency forms over virtual link
- ✓ E.Verify virtual link with show ip ospf virtual-links
Why A: Virtual links require area 0 transit area, and must be configured on both ABRs. The steps ensure proper connectivity: identify endpoints, configure on each router, and verify.
Last reviewed: Jun 18, 2026
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