Quick Answer
The answer is 10 seconds. On broadcast multi-access networks like Ethernet, OSPF defaults to a hello interval of 10 seconds, as defined in RFC 2328, to maintain neighbor adjacencies and quickly detect link failures. This timer governs how often a router sends Hello packets out of an interface; the corresponding dead interval is 40 seconds, or four times the hello interval. For the ENCOR 350-401 exam, this is a fundamental OSPF fact that often appears in multiple-choice questions testing your knowledge of default timers per network type. A common trap is confusing the 10-second default on broadcast networks with the 30-second default on non-broadcast multi-access (NBMA) networks like Frame Relay. Remember the memory tip: "Broadcast is fast, so 10 seconds; NBMA is slow, so 30."
This 350-401 practice question tests your understanding of ospf. 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.
What is the default OSPF hello interval on a broadcast multi-access network (e.g., Ethernet)?
5 seconds
Why wrong: 5 seconds is used for point-to-point networks with non-default timers, but not the default for broadcast.
10 seconds
The default hello interval for broadcast and point-to-point networks is 10 seconds.
30 seconds
Why wrong: 30 seconds is the default for NBMA networks, not broadcast.
40 seconds
Why wrong: 40 seconds is the default dead interval, not the hello interval.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
10 seconds
On broadcast multi-access networks like Ethernet, OSPF defaults to a hello interval of 10 seconds. This is defined in RFC 2328 and is used to maintain neighbor relationships and detect failures quickly. The corresponding dead interval is 40 seconds (4 times the hello interval).
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
5 seconds
Why it's wrong here
5 seconds is used for point-to-point networks with non-default timers, but not the default for broadcast.
10 seconds
Why this is correct
The default hello interval for broadcast and point-to-point networks is 10 seconds.
Related concept
Read the scenario before looking for a memorised answer.
30 seconds
Why it's wrong here
30 seconds is the default for NBMA networks, not broadcast.
40 seconds
Why it's wrong here
40 seconds is the default dead interval, not the hello interval.
Common exam traps
Cisco often tests the distinction between hello and dead intervals, and the trap here is confusing the default dead interval (40 seconds) with the hello interval (10 seconds) on broadcast multi-access networks.
Detailed technical explanation
The hello interval is configured under the 'ip ospf hello-interval' interface command, and changing it automatically adjusts the dead interval to 4 times the new value unless explicitly overridden. In real-world scenarios, mismatched hello intervals between OSPF neighbors prevent adjacency formation, which is a common troubleshooting issue when connecting different network types or manually tuning timers.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
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FAQ
OSPF — This question tests OSPF — Read the scenario before looking for a memorised answer..
The correct answer is: 10 seconds — On broadcast multi-access networks like Ethernet, OSPF defaults to a hello interval of 10 seconds. This is defined in RFC 2328 and is used to maintain neighbor relationships and detect failures quickly. The corresponding dead interval is 40 seconds (4 times the hello interval).
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.
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