easyMultiple Choice
350-401 Practice Question: The default EIGRP hello interval on a…
What is the default EIGRP hello interval on a point-to-point serial link?
⚠ Common exam trap
Cisco often tests the distinction between EIGRP and OSPF hello intervals, so the trap here is that candidates confuse the 10-second OSPF default with EIGRP's 5-second default on point-to-point 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
✓
5 seconds
The default EIGRP hello interval on a point-to-point serial link is 5 seconds. EIGRP uses different hello intervals depending on the media type: for high-speed broadcast links (e.g., Ethernet) and point-to-point links, the default is 5 seconds; for multipoint non-broadcast links (e.g., Frame Relay), the default is 60 seconds.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
5 seconds
Why this is correct
The default EIGRP hello interval on point-to-point serial links is 5 seconds. This design ensures fast neighbor discovery and rapid convergence since EIGRP relies on periodic hello packets (multicast to 224.0.0.10) to maintain adjacency. The corresponding hold time defaults to 15 seconds (three times the hello interval), allowing only one missed hello before the neighbor is declared down. This 5-second default also applies to Ethernet and most high-speed media, making it the standard EIGRP hello interval.
- ✗
10 seconds
Why it's wrong here
This value is the default hello interval for OSPF on broadcast and point-to-point networks, not for EIGRP. EIGRP never uses a 10-second hello as a platform default; it uses 5 seconds on high-speed interfaces like point-to-point serial and 60 seconds on low-speed multipoint NBMA interfaces. Selecting 10 seconds indicates a mix-up between the two routing protocols' default timers, which is a common exam trap. EIGRP's design goal of faster convergence would be undermined by a 10-second hello when a 5-second value is already configured.
- ✗
30 seconds
Why it's wrong here
There is no standard EIGRP default hello interval of 30 seconds; EIGRP operates with either 5-second or 60-second defaults depending on link type and speed. A 30-second hello would be too slow for EIGRP's rapid convergence requirements, as it would delay neighbor loss detection significantly. This value is not used by any major IGP as a default hello timer, making it a distractor. Administrators can manually tune the hello interval, but 30 seconds is never a default for point-to-point serial links.
- ✗
60 seconds
Why it's wrong here
While 60 seconds is a legitimate EIGRP default hello interval, it applies only to multipoint NBMA interfaces (e.g., Frame Relay or ATM) with link speeds of T1 (1.544 Mbps) or slower. On such low-speed NBMA networks, frequent hellos would consume excessive bandwidth, so EIGRP increases the hello interval to 60 seconds and the hold time to 180 seconds. Point-to-point serial links, regardless of speed, use the 5-second default because they have a single neighbor and no broadcast traffic overhead. Therefore, 60 seconds is incorrect for this question's point-to-point serial scenario.
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.