This 350-401 practice question tests your understanding of network function virtualization. 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 an Ethernet link?
10 seconds
Correct. The default hello interval for OSPF on Ethernet is 10 seconds.
30 seconds
Why wrong: Incorrect. 30 seconds is the default for NBMA networks, not Ethernet.
40 seconds
Why wrong: Incorrect. 40 seconds is the default dead interval (4 * hello) on Ethernet, not the hello interval.
5 seconds
Why wrong: Incorrect. 5 seconds is not a standard OSPF default 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 Ethernet (broadcast multi-access) links, OSPF defaults to a hello interval of 10 seconds, as specified in RFC 2328. This interval allows OSPF routers to quickly detect neighbor failures while keeping control overhead low. The dead interval is automatically set to 40 seconds (four times the hello interval) on such links.
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.
10 seconds
Why this is correct
Correct. The default hello interval for OSPF on Ethernet is 10 seconds.
Related concept
Read the scenario before looking for a memorised answer.
30 seconds
Why it's wrong here
Incorrect. 30 seconds is the default for NBMA networks, not Ethernet.
40 seconds
Why it's wrong here
Incorrect. 40 seconds is the default dead interval (4 * hello) on Ethernet, not the hello interval.
5 seconds
Why it's wrong here
Incorrect. 5 seconds is not a standard OSPF default interval.
Common exam traps
Cisco often tests the confusion between the OSPF hello interval on Ethernet (10 seconds) and the dead interval (40 seconds), or between different network types like NBMA (30 seconds) and point-to-point (5 seconds).
Detailed technical explanation
The OSPF hello and dead intervals are configured per interface and must match between neighbors for adjacency to form. On Ethernet, the 10-second hello interval ensures that a dead neighbor is detected within 40 seconds (dead interval), which is critical for fast convergence in a switched network. In real-world scenarios, changing these timers to sub-second values (e.g., using the 'ip ospf dead-interval minimal hello-multiplier' command) can reduce convergence time but increases CPU load and control traffic.
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
Network Function Virtualization — This question tests Network Function Virtualization — Read the scenario before looking for a memorised answer..
The correct answer is: 10 seconds — On Ethernet (broadcast multi-access) links, OSPF defaults to a hello interval of 10 seconds, as specified in RFC 2328. This interval allows OSPF routers to quickly detect neighbor failures while keeping control overhead low. The dead interval is automatically set to 40 seconds (four times the hello interval) on such links.
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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