This JNCIA-JUNOS practice question tests your understanding of routing fundamentals. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
Exhibit
user@router> show route protocol bgp 10.1.1.0/24
inet.0: 10 destinations, 12 routes (8 active, 2 holddown, 2 hidden)
+ = Active Route, - = Last Active, * = Both
10.1.1.0/24 [BGP/170] 00:01:23, localpref 100, from 10.0.0.2
Next hop: 192.168.100.1 via ge-0/0/0.0
(hidden: next hop unreachable)
Refer to the exhibit. What is the most likely cause of this BGP route being hidden?
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.
Exhibit
user@router> show route protocol bgp 10.1.1.0/24
inet.0: 10 destinations, 12 routes (8 active, 2 holddown, 2 hidden)
+ = Active Route, - = Last Active, * = Both
10.1.1.0/24 [BGP/170] 00:01:23, localpref 100, from 10.0.0.2
Next hop: 192.168.100.1 via ge-0/0/0.0
(hidden: next hop unreachable)
A
The route has a higher preference than another route.
Why wrong: The hidden reason explicitly states next-hop unreachable, not preference conflict.
B
The BGP session to 10.0.0.2 is down.
Why wrong: If the session were down, the route would not appear at all.
C
The prefix 10.1.1.0/24 is filtered by an import policy.
Why wrong: If filtered, the route would not appear in the routing table at all, not as hidden.
D
The next-hop 192.168.100.1 is not reachable via any active route.
The reason given is 'next hop unreachable', so the next-hop is not reachable.
The answer is that the BGP route is hidden because the next-hop 192.168.100.1 is not reachable via any active route. This occurs because Junos performs a recursive route lookup for the BGP next-hop address in the inet.0 routing table; if no valid, active route exists to that IP, the BGP route is suppressed and marked as hidden with the reason "next hop unreachable." On the JNCIA-Junos exam, this concept tests your understanding of BGP route selection and the importance of an IGP or static route covering the next-hop, often appearing in troubleshooting exhibits where a route is present in the BGP table but absent from the forwarding table. A common trap is assuming the route is hidden due to a prefix-list or AS-path issue, but the exhibit’s explicit "next hop unreachable" reason points directly to a missing route for 192.168.100.1. Memory tip: think of BGP as a passenger that needs a working road (the IGP route) to reach its destination—no road, no ride.
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 next-hop 192.168.100.1 is not reachable via any active route.
In JUNOS, a BGP route is hidden when the next-hop address is not reachable via any active route in the routing table. The show route protocol bgp command displays the route as hidden if the next-hop 192.168.100.1 is not resolvable, because BGP requires a valid IGP or static route to the next-hop for the route to be considered active and installed in the forwarding 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 route has a higher preference than another route.
Why it's wrong here
The hidden reason explicitly states next-hop unreachable, not preference conflict.
✗
The BGP session to 10.0.0.2 is down.
Why it's wrong here
If the session were down, the route would not appear at all.
✗
The prefix 10.1.1.0/24 is filtered by an import policy.
Why it's wrong here
If filtered, the route would not appear in the routing table at all, not as hidden.
✓
The next-hop 192.168.100.1 is not reachable via any active route.
Why this is correct
The reason given is 'next hop unreachable', so the next-hop is not reachable.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse a hidden route with a route that is filtered by policy or has a higher preference, but JUNOS specifically uses the 'hidden' flag to indicate next-hop unreachability, not policy rejection or preference comparison.
Detailed technical explanation
How to think about this question
JUNOS BGP uses the next-hop resolution mechanism defined in RFC 4271; a route is considered valid only if the next-hop address is reachable via an active route in the inet.0 table, including static routes or directly connected interfaces. The hidden state can be verified with the command 'show route protocol bgp hidden' or by checking the 'Next-hop' field in 'show route extensive', which will indicate 'Unresolved' if the next-hop is not reachable. This behavior is distinct from Cisco IOS, where BGP routes with unreachable next-hops are simply not installed in the routing table without a hidden designation.
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 practitioner preparing for the JNCIA-JUNOS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Visual reference
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.
Routing Fundamentals — This question tests Routing Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The next-hop 192.168.100.1 is not reachable via any active route. — In JUNOS, a BGP route is hidden when the next-hop address is not reachable via any active route in the routing table. The show route protocol bgp command displays the route as hidden if the next-hop 192.168.100.1 is not resolvable, because BGP requires a valid IGP or static route to the next-hop for the route to be considered active and installed in the forwarding table.
What should I do if I get this JNCIA-JUNOS 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A route learned via BGP appears as 'hidden' in the routing table. Which condition is most likely the cause?
hard
A.The BGP route has a higher AS path length than another route
B.The BGP route has been rejected by a policy
✓ C.The BGP next-hop is unreachable
D.The BGP local preference is too high
Why C: In JUNOS, a BGP route is marked as 'hidden' in the routing table when the next-hop address is not reachable via any active route in the inet.0 table. This is a fundamental BGP path selection prerequisite: the next-hop must be resolvable (typically via an IGP or static route) for the route to be considered active and installed.
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This JNCIA-JUNOS practice question is part of Courseiva's free Juniper Networks 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 JNCIA-JUNOS exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.