- A
The OSPF network type is non-broadcast and the neighbors are not manually configured.
Correct because in non-broadcast networks, OSPF neighbors must be manually configured; otherwise, the adjacency will remain in 2WAY.
- B
The OSPF router priority is set to 0 on both routers.
Why wrong: Incorrect because if both routers have priority 0, they cannot become DR/BDR, but they can still form full adjacency with each other if the network type is broadcast.
- C
The OSPF area ID is different.
Why wrong: Incorrect because mismatched area IDs would prevent the adjacency from reaching 2WAY; they would be stuck in INIT.
- D
The Frame Relay map is missing for the broadcast keyword.
Why wrong: Incorrect because missing broadcast keyword would prevent hello packets from being sent, causing the adjacency to be stuck in DOWN or INIT.
Quick Answer
The answer is that the OSPF adjacency is stuck in the 2WAY state because the OSPF network type is non-broadcast (NBMA) and the neighbors are not manually configured. On Frame Relay interfaces, the default OSPF network type for physical links is non-broadcast, which means the router will not send multicast Hello packets for neighbor discovery. Without the explicit neighbor command, each router sees the other’s Hello but cannot transition past the 2WAY state because NBMA requires a manual neighbor statement to establish a full adjacency. On the ENCOR 350-401 exam, this scenario tests your understanding of how OSPF behaves over different Layer 2 technologies, especially the critical difference between broadcast and non-broadcast network types. A common trap is assuming that matching Hello and Dead intervals alone guarantee adjacency progression, but on NBMA networks, manual neighbor configuration is mandatory. Memory tip: “NBMA needs a name” — you must use the neighbor command to name each peer.
350-401 OSPF Practice Question
This 350-401 practice question tests your understanding of ospf. 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 is troubleshooting an OSPF adjacency issue between two routers connected via a Frame Relay network. The adjacency is stuck in the 2WAY state. The engineer has verified that the routers are in the same area and have matching hello/dead intervals. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
The OSPF network type is non-broadcast and the neighbors are not manually configured.
In OSPF over Frame Relay, the default network type for physical interfaces is non-broadcast (NBMA). On an NBMA network, OSPF does not send multicast Hello packets; instead, neighbors must be manually configured using the 'neighbor' command. Without manual neighbor configuration, the routers will not proceed past the 2WAY state because they cannot form a full adjacency without explicit neighbor discovery.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 OSPF network type is non-broadcast and the neighbors are not manually configured.
Why this is correct
Correct because in non-broadcast networks, OSPF neighbors must be manually configured; otherwise, the adjacency will remain in 2WAY.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The OSPF router priority is set to 0 on both routers.
Why it's wrong here
Incorrect because if both routers have priority 0, they cannot become DR/BDR, but they can still form full adjacency with each other if the network type is broadcast.
- ✗
The OSPF area ID is different.
Why it's wrong here
Incorrect because mismatched area IDs would prevent the adjacency from reaching 2WAY; they would be stuck in INIT.
- ✗
The Frame Relay map is missing for the broadcast keyword.
Why it's wrong here
Incorrect because missing broadcast keyword would prevent hello packets from being sent, causing the adjacency to be stuck in DOWN or INIT.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume the 2WAY state is normal or that it indicates a DR/BDR election issue, but in NBMA networks it specifically indicates that OSPF is not attempting to form a full adjacency because neighbors are not manually defined.
Trap categories for this question
Keyword trap
Incorrect because missing broadcast keyword would prevent hello packets from being sent, causing the adjacency to be stuck in DOWN or INIT.
Detailed technical explanation
How to think about this question
OSPF over NBMA networks requires the 'neighbor' command to statically define the neighbor's IP address and optionally its priority and poll interval. Without this, the router will not send unicast Hellos to the remote router, so the adjacency remains stuck in 2WAY (the state where both routers have seen each other's Hellos but no further progress is made). In real-world deployments, changing the network type to 'point-to-multipoint' or 'broadcast' can avoid this manual configuration, but the default NBMA type is a common source of troubleshooting issues.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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
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FAQ
Questions learners often ask
What does this 350-401 question test?
OSPF — This question tests OSPF — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The OSPF network type is non-broadcast and the neighbors are not manually configured. — In OSPF over Frame Relay, the default network type for physical interfaces is non-broadcast (NBMA). On an NBMA network, OSPF does not send multicast Hello packets; instead, neighbors must be manually configured using the 'neighbor' command. Without manual neighbor configuration, the routers will not proceed past the 2WAY state because they cannot form a full adjacency without explicit neighbor discovery.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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. A network engineer issues the following command on Router R6: R6# debug ip ospf hello OSPF: Send hello to 224.0.0.5 via GigabitEthernet0/0 (192.168.1.6) OSPF: Rcv hello from 1.1.1.1, GigabitEthernet0/0, area 0.0.0.0 Neighbor state is 2WAY, options 0x2 OSPF: End of hello processing Based on this output, what can be concluded?
hard- A.R6 has formed a full adjacency with neighbor 1.1.1.1.
- B.The hello packet was sent to the DR/BDR multicast address 224.0.0.6.
- ✓ C.R6 and 1.1.1.1 are neighbors, but a full adjacency may not yet be formed.
- D.The OSPF network type is point-to-point.
Why C: The debug output shows the neighbor state is 2WAY, which indicates that R6 has received a hello from 1.1.1.1 and bidirectional communication is established, but a full adjacency has not yet been formed. In OSPF, the 2WAY state is a prerequisite for advancing to the ExStart state and eventually to FULL, but on multiaccess networks, the router must also wait for the Designated Router (DR) and Backup Designated Router (BDR) election process to complete before proceeding. Therefore, option C correctly states that R6 and 1.1.1.1 are neighbors, but a full adjacency may not yet be formed.
Last reviewed: Jun 24, 2026
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