- A
The BGP next-hop is not reachable because the IGP does not advertise it, and no static route exists.
BGP checks the reachability of the next-hop before installing the route. Without reachability, the route is hidden from the routing table.
- B
The BGP synchronization rule is enabled, causing the route to be suppressed until the IGP learns it.
Why wrong: Synchronization is disabled by default in modern IOS versions, and even if enabled, it would require the IGP to carry the prefix, not the next-hop.
- C
The next-hop-self command is missing on the eBGP neighbor, so the iBGP router sees the external next-hop.
Why wrong: Even if next-hop-self is missing, the iBGP router would still see the external next-hop, but the issue is reachability, not the next-hop address itself.
- D
The BGP table shows the route as valid, but the routing table does not install it due to administrative distance.
Why wrong: Administrative distance affects preference among routes, but the route must first be reachable. The route is not even considered for installation.
Quick Answer
The correct answer is that the BGP next-hop is unreachable because the IGP does not advertise it and no static route exists. For any BGP route to be installed in the routing table, the next-hop address must be reachable via an IGP or a static route; without this reachability, the route stays in the BGP table but is never placed into the IP routing table. This scenario directly tests the BGP next-hop resolution rule, a core concept in the Cisco CCNP ENARSI 300-410 exam, where candidates must understand that iBGP routes learned from an eBGP neighbor require the IGP to carry the next-hop address—or a static route must fill the gap. A common trap is assuming that an established BGP session guarantees route installation, but the session only ensures TCP connectivity, not next-hop reachability. Remember the memory tip: “BGP installs only when the next-hop is in the IGP’s hands.”
300-410 Device Access Control Practice Question
This 300-410 practice question tests your understanding of device access control. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An engineer configures iBGP between two routers in the same AS. The BGP session comes up, but the routes learned from the eBGP neighbor are not installed in the routing table. The IGP does not carry the BGP next-hop address. Which is the most likely explanation?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 next-hop is not reachable because the IGP does not advertise it, and no static route exists.
The correct answer is A because for a BGP route to be installed in the routing table, the next-hop address must be reachable via the IGP or a static route. Since the IGP does not carry the BGP next-hop address and no static route exists, the next-hop is unreachable, causing the route to remain in the BGP table but not be installed in the routing table.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 BGP next-hop is not reachable because the IGP does not advertise it, and no static route exists.
Why this is correct
BGP checks the reachability of the next-hop before installing the route. Without reachability, the route is hidden from the routing table.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The BGP synchronization rule is enabled, causing the route to be suppressed until the IGP learns it.
Why it's wrong here
Synchronization is disabled by default in modern IOS versions, and even if enabled, it would require the IGP to carry the prefix, not the next-hop.
- ✗
The next-hop-self command is missing on the eBGP neighbor, so the iBGP router sees the external next-hop.
Why it's wrong here
Even if next-hop-self is missing, the iBGP router would still see the external next-hop, but the issue is reachability, not the next-hop address itself.
- ✗
The BGP table shows the route as valid, but the routing table does not install it due to administrative distance.
Why it's wrong here
Administrative distance affects preference among routes, but the route must first be reachable. The route is not even considered for installation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between BGP table validity and routing table installation, where candidates mistakenly think a valid BGP route automatically installs, ignoring the next-hop reachability requirement.
Detailed technical explanation
How to think about this question
BGP route installation requires the next-hop to be recursively resolved via the routing table. If the next-hop is not reachable (e.g., via IGP or static route), the route is marked as 'hidden' or 'invalid' in the BGP table and is not considered for the routing table. In real-world scenarios, this often occurs when iBGP routers learn external routes but the IGP (e.g., OSPF or EIGRP) does not include the eBGP neighbor's loopback or interface IP, requiring either a static route or the next-hop-self command on the eBGP peer.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this 300-410 question test?
Device Access Control — This question tests Device Access Control — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The BGP next-hop is not reachable because the IGP does not advertise it, and no static route exists. — The correct answer is A because for a BGP route to be installed in the routing table, the next-hop address must be reachable via the IGP or a static route. Since the IGP does not carry the BGP next-hop address and no static route exists, the next-hop is unreachable, causing the route to remain in the BGP table but not be installed in the routing table.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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