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300-410 Practice Question: An engineer configures iBGP between two routers…
An engineer configures iBGP between two routers in the same AS. The routes learned via iBGP are not being installed in the routing table, even though the next-hop is reachable. The IGP is OSPF and the routes are present in the BGP table. Which is the most likely explanation?
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 BGP synchronization rule is enabled, and the IGP does not have a route for the same prefix.
BGP synchronization rule (disabled by default in modern IOS) requires that for a route learned via iBGP to be considered valid, the same prefix must be present in the IGP routing table. If synchronization is enabled and the IGP does not carry the prefix, the route is not installed.
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 next-hop-self command is missing on the iBGP neighbor configuration.
Why it's wrong here
Next-hop-self is required for eBGP or when the next-hop is not reachable via IGP, but the issue here is synchronization.
- ✓
The BGP synchronization rule is enabled, and the IGP does not have a route for the same prefix.
Why this is correct
With synchronization enabled, iBGP routes are not installed unless the IGP also knows about the prefix.
- ✗
The administrative distance of iBGP (200) is higher than OSPF (110), so OSPF routes are preferred.
Why it's wrong here
Administrative distance affects route selection when the same prefix is learned from multiple protocols, but the issue is that the route is not installed at all.
- ✗
The BGP table indicates the route is valid but the best path selection fails due to missing MED.
Why it's wrong here
Missing MED does not prevent route installation; it only affects path selection among multiple paths.
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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JA
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.