easyMultiple Choice
CCNP Practice Question: The default OSPF hello interval on an Ethernet…
What is the default OSPF hello interval on an Ethernet link in a Cisco router?
⚠ Common exam trap
Cisco often tests the default OSPF hello interval on Ethernet (broadcast) networks, and the trap here is that candidates confuse it with the dead interval (40 seconds) or with the hello interval used on other network types like NBMA (30 seconds).
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 (which is a broadcast multi-access network type) is 10 seconds. This is defined in RFC 2328 and is the default on Cisco routers for broadcast and point-to-point network types. The hello interval determines how often a router sends hello packets to discover and maintain neighbor relationships.
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
The default OSPF HelloInterval on an Ethernet broadcast multi-access link is 10 seconds. Every 10 seconds a router sends an OSPF Hello packet out each OSPF-enabled interface to discover neighboring routers and maintain the neighbor relationship. This value is defined in RFC 2328 and is also the default for point-to-point links, but 10 seconds is the correct default specifically for the Ethernet network type in this question.
- ✗
30 seconds
Why it's wrong here
The 30-second value is the default OSPF HelloInterval for NBMA (Non-Broadcast Multi-Access) networks such as Frame Relay, ATM, and X.25, where multicast Hello delivery is not natively supported. Ethernet, by contrast, natively supports multicast/broadcast, so OSPF uses the faster 10-second HelloInterval as its default. A 30-second hello would not be the default on Ethernet, and a neighbor using the default dead interval of 40 seconds would be declared down almost immediately because the dead interval is only four times the default 10-second hello, not four times 30 seconds.
- ✗
5 seconds
Why it's wrong here
A 5-second hello interval is the default for OSPF on NBMA (Non-Broadcast Multi-Access) networks, not for Ethernet. On an Ethernet broadcast multi-access link, the default hello interval is 10 seconds. This option is tempting because 5 seconds is the default for OSPF point-to-point and NBMA interfaces, so it is correct for those specific network types, but the stem explicitly specifies an Ethernet link.
- ✗
40 seconds
Why it's wrong here
The 40-second value is not a hello interval at all — it is the default OSPF RouterDeadInterval on broadcast and point-to-point networks, including Ethernet. This dead interval is four times the HelloInterval (4 × 10 seconds = 40 seconds) and represents how long a router waits without receiving a Hello packet before declaring its neighbor down. Since the question specifically asks for the hello interval, this option is incorrect, even though 40 seconds is the related default dead timer for the same interface type.
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.