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300-410 R1 and R2 are OSPF neighbors with BFD enabled Practice Question
R1 and R2 are OSPF neighbors with BFD enabled. R1#show ip ospf neighbor shows R2 as 'FULL/DR'. R1#show bfd neighbors shows the session as 'Up' with R2. R2#show bfd neighbors shows the session as 'Up' with R1. However, R1#show ip route shows that the route to 10.1.1.0/24 via R2 is missing. R1 has 'summary-address 10.1.1.0 255.255.255.0' configured under OSPF. What is the root cause?
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
✓
The OSPF summary-address on R1 is suppressing the more specific route from R2.
OSPF summary-address on an ABR or ASBR suppresses more specific routes. If R1 is an ABR and has a summary-address for 10.1.1.0/24, it will not install the specific route from R2, even though BFD and OSPF adjacency are fine. The summary route may be advertised instead, but the specific route is missing from the routing table.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The OSPF summary-address on R1 is suppressing the more specific route from R2.
Why this is correct
The summary-address command causes OSPF to advertise only the summary and suppress more specific routes, so the specific route from R2 is not installed.
- ✗
BFD is causing the route to be removed due to fast detection.
Why it's wrong here
BFD session is up, so no route removal.
- ✗
R2 is not advertising the route due to a filtering policy.
Why it's wrong here
The adjacency is full, so routes are exchanged.
- ✗
The OSPF cost on R1 is too high, causing the route to be ignored.
Why it's wrong here
Cost does not cause route suppression.
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 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.