The answer is the Non-Broadcast (NBMA) OSPF network type. This is correct because on Cisco IOS, the NBMA network type is designed for non-broadcast multi-access environments like Frame Relay or X.25, where neighbors cannot be discovered dynamically via multicast, so the protocol uses longer timers to compensate for the lack of hello-based discovery; specifically, the default OSPF NBMA hello interval is 30 seconds and the dead interval is 120 seconds, four times the hello interval. On the Cisco CCNP ENARSI 300-410 exam, this distinction tests your understanding of how OSPF network types affect neighbor formation and convergence, often appearing in questions that contrast NBMA with broadcast or point-to-point types—a common trap is confusing NBMA’s 30-second hello with the 10-second default used on broadcast networks. To remember, think “NBMA = Not Broadcast, More Awkward,” meaning longer timers: 30 seconds for hello, 120 seconds for dead.
300-410 OSPF Troubleshooting (v2/v3) Practice Question
This 300-410 practice question tests your understanding of ospf troubleshooting (v2/v3). Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 OSPF network type defaults to a hello interval of 30 seconds and a dead interval of 120 seconds on Cisco IOS?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Non-Broadcast (NBMA)
The Non-Broadcast Multi-Access (NBMA) network type uses a default hello interval of 30 seconds and a dead interval of 120 seconds, as per Cisco implementation.
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.
✗
Broadcast
Why it's wrong here
Incorrect. Broadcast network type uses hello interval of 10 seconds and dead interval of 40 seconds.
✗
Point-to-point
Why it's wrong here
Incorrect. Point-to-point network type uses hello interval of 10 seconds and dead interval of 40 seconds.
✓
Non-Broadcast (NBMA)
Why this is correct
Correct. NBMA network type defaults to hello interval 30 seconds and dead interval 120 seconds.
Incorrect. Point-to-multipoint network type uses hello interval of 30 seconds but dead interval of 120 seconds is not the default.
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 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: Non-Broadcast (NBMA) — The Non-Broadcast Multi-Access (NBMA) network type uses a default hello interval of 30 seconds and a dead interval of 120 seconds, as per Cisco implementation.
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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