Quick Answer
The correct answer is 10 seconds. On broadcast multi-access networks like Ethernet, OSPF routers use a default hello interval of 10 seconds to maintain neighbor relationships and detect link failures quickly. This interval is defined in RFC 2328 because broadcast networks allow efficient multicast Hello packets (224.0.0.5) to all OSPF routers simultaneously, enabling rapid convergence without excessive overhead. On the ENCOR 350-401 exam, this concept tests your understanding of OSPF network types and their default timers—a common trap is confusing the 10-second broadcast interval with the 30-second default on non-broadcast or point-to-multipoint networks. You may also see a question where the dead interval is four times the hello interval, so knowing that 40 seconds is the default dead interval on broadcast networks reinforces the 10-second hello. A simple memory tip: think of a standard Ethernet cable—10 seconds for hello, just like the number on a classic 10Base-T cable.
This 350-401 practice question tests your understanding of netflow and telemetry. 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)?
10 seconds
This is the default hello interval for broadcast and point-to-point OSPF networks.
30 seconds
Why wrong: 30 seconds is the default hello interval for NBMA networks (e.g., Frame Relay).
40 seconds
Why wrong: 40 seconds is not a standard OSPF hello interval.
20 seconds
Why wrong: 20 seconds is not a default OSPF hello interval; 10 seconds is correct for Ethernet.
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
OSPF uses different hello intervals depending on the network type. On broadcast and point-to-point networks, the default hello interval is 10 seconds.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
10 seconds
30 seconds
Why it's wrong here
30 seconds is the default hello interval for NBMA networks (e.g., Frame Relay).
40 seconds
Why it's wrong here
40 seconds is not a standard OSPF hello interval.
20 seconds
Why it's wrong here
20 seconds is not a default OSPF hello interval; 10 seconds is correct for Ethernet.
Common exam traps
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
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.
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
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
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 350-401 OSPF questions on adjacency and route selection.
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FAQ
NetFlow and Telemetry — This question tests NetFlow and Telemetry — OSPF neighbours must agree on key parameters..
The correct answer is: 10 seconds — OSPF uses different hello intervals depending on the network type. On broadcast and point-to-point networks, the default hello interval is 10 seconds.
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 350-401 OSPF questions on adjacency and route selection.
OSPF neighbours must agree on key parameters.
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Last reviewed: Jun 18, 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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