easyMultiple Choice
350-401 Practice Question: The default OSPF hello interval on an Ethernet…
What is the default OSPF hello interval on an Ethernet link?
⚠ Common exam trap
Cisco often tests the confusion between the OSPF hello interval and dead interval, where candidates mistakenly select 40 seconds (the dead interval) instead of 10 seconds (the hello interval) on Ethernet links.
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
✓
10 seconds
The default OSPF hello interval on an Ethernet link is 10 seconds, as specified in RFC 2328. Ethernet is a broadcast multi-access network type, and OSPF uses a 10-second hello interval on such networks to maintain neighbor adjacencies and detect failures within the dead interval (default 40 seconds, or 4 times the hello interval).
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
10 seconds
Why this is correct
On Ethernet broadcast multi-access networks, OSPF's default hello interval is 10 seconds. This value is defined in RFC 2328 for broadcast and point-to-point interfaces, and the associated dead interval is 40 seconds (4 times the hello). The 10-second hello keeps neighbor adjacency establishment quick while maintaining a reasonable control-plane overhead.
- ✗
30 seconds
Why it's wrong here
30 seconds is the RFC-mandated default hello interval for OSPF on non-broadcast multi-access (NBMA) networks, such as Frame Relay or ATM. It is not the default on Ethernet; broadcast media always use 10 seconds by default. If a user manually sets 30 seconds on an Ethernet link, the interface must use matching timers with neighbors, but this unnecessarily slows down hello-based failure detection and defeats OSPF's fast convergence expectations on LANs.
- ✗
40 seconds
Why it's wrong here
40 seconds is frequently confused with the OSPF dead interval, which on broadcast networks defaults to 40 seconds (4 multiplied by the 10-second hello timer). To form an adjacency, OSPF neighbors require a dead interval at least as long as the hello interval; setting the hello interval to 40 seconds would make it equal to the dead interval, so any single lost hello packet immediately tears down the neighbor relationship. No standard OSPF deployment uses a 40-second hello interval, and RFC 2328 does not list it as a default for any interface type.
- ✗
5 seconds
Why it's wrong here
5 seconds is not a default OSPF timer, but it can be configured on a Cisco interface with the ip ospf hello-interval 5 command to speed up failure detection. On Ethernet, changing the hello interval from 10 to 5 doubles the amount of OSPF hello traffic and requires a corresponding dead interval of 20 seconds to maintain the 4:1 ratio. This aggressive tuning is rarely used because it increases bandwidth consumption and can cause flapping on congested or lossy links, and any misconfigured neighbor with mismatched timers will fail to form an adjacency.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.