The answer is that the virtual link is functioning correctly and the adjacency is full. This conclusion is drawn directly from the show ip ospf virtual-links status output, which displays "Virtual Link OSPF_VL0 to router 10.1.1.3 is up" and "Adjacency State FULL," confirming that the OSPF virtual link has successfully established a neighbor relationship across the transit area. In OSPF, a virtual link acts as a logical tunnel through a non-backbone area to connect a disconnected area to Area 0, and the FULL adjacency state indicates that the link is operational and exchanging routing information properly. On the Cisco CCNP ENARSI 300-410 exam, this command tests your ability to interpret OSPF virtual link verification output, often appearing in troubleshooting scenarios where a missing or flapping virtual link causes routing black holes. A common trap is mistaking the "DoNotAge LSA" or "demand circuit" flags for a problem, but these are normal optimizations that suppress hello packets on stable links. Memory tip: "FULL means functional" — if you see FULL adjacency, the virtual link is working, regardless of other flags.
300-410 OSPF Troubleshooting (v2/v3) Practice Question
This 300-410 practice question tests your understanding of ospf troubleshooting (v2/v3). 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.
A network engineer runs the following command on Router R1:
R1# show ip ospf virtual-links
Virtual Link OSPF_VL0 to router 10.1.1.3 is up
Run as demand circuit
DoNotAge LSA allowed.
Transit area 1, via interface GigabitEthernet0/0, Cost of using 10
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:08
Adjacency State FULL
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The virtual link is functioning correctly and the adjacency is full.
The virtual link to router 10.1.1.3 is up and in FULL state. It is running as a demand circuit, which suppresses hello packets when the link is stable. The transit area is area 1.
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.
✗
The virtual link is using area 0 as the transit area.
Why it's wrong here
The transit area is area 1, not area 0.
✓
The virtual link is functioning correctly and the adjacency is full.
Why this is correct
The state is FULL and the link is up, indicating proper operation.
Router R1 is not receiving hello packets on the virtual link.
Why it's wrong here
The virtual link is a demand circuit, so hellos are suppressed; this is normal, not a problem.
✗
The virtual link has a cost of 1.
Why it's wrong here
The cost is 10, as shown.
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
The cost is 10, as shown.
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.
OSPF Troubleshooting (v2/v3) — This question tests OSPF Troubleshooting (v2/v3) — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: The virtual link is functioning correctly and the adjacency is full. — The virtual link to router 10.1.1.3 is up and in FULL state. It is running as a demand circuit, which suppresses hello packets when the link is stable. The transit area is area 1.
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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