hardMultiple Choice
300-410 Practice Question: The default OSPF reference bandwidth used in the…
What is the default OSPF reference bandwidth used in the metric calculation on Cisco IOS-XE?
⚠ Common exam trap
The trap is confusing the default reference bandwidth (100 Mbps) with the commonly recommended modern value (1000 or 10000 Mbps) — candidates who have configured 'auto-cost reference-bandwidth 1000' in labs often pick 1000 Mbps as the default.
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
✓
100 Mbps
Cisco IOS-XE uses a default OSPF reference bandwidth of 100 Mbps (10^8), which is the historical default inherited from early OSPF implementations. The OSPF cost is calculated as reference bandwidth divided by interface bandwidth, so a 100 Mbps interface has a cost of 1, and faster interfaces (1 Gbps, 10 Gbps) all default to cost 1 unless the reference bandwidth is changed. This is why modern networks often raise the reference bandwidth to 1000 or 10000 Mbps.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
100 Mbps
Why this is correct
Cisco IOS-XE calculates OSPF cost as reference bandwidth divided by interface bandwidth, and the default reference is 100 Mbps. Any interface at or above 100 Mbps therefore yields a cost of 1, which is why Gigabit and faster links become indistinguishable without manually raising the reference bandwidth.
- ✗
1000 Mbps
Why it's wrong here
Cisco IOS-XE defaults the OSPF reference bandwidth to 100 Mbps, so 1000 Mbps would be a manually configured value. It tempts because 1000 Mbps matches common Gigabit interface speeds, but the default reference is 100 Mbps, giving a Gigabit link a cost of 1.
- ✗
10 Mbps
Why it's wrong here
The default OSPF reference bandwidth on Cisco IOS-XE is 100 Mbps, not 10 Mbps; 10 Mbps corresponds to the cost value assigned to a 10 Mbps interface under that default. It tempts because early Ethernet ran at 10 Mbps, but the reference itself is 100 Mbps.
- ✗
10000 Mbps
Why it's wrong here
Cisco IOS-XE defaults to a reference bandwidth of 100 Mbps, so 10000 Mbps would require the 'auto-cost reference-bandwidth 10000' command. It tempts because 10 Gbps is a common modern interface speed, and setting the reference to match your fastest links is a legitimate design choice to preserve metric granularity on high-speed networks.
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.
Go deeper
Related to this question
About these practice questions
Courseiva writes every 300-410 question from scratch — 1,401 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 300-410 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 300-410 exam.