- A
Disable the eBGP session on R2 to remove the BGP routes from the routing table.
Why wrong: Incorrect: BGP routes on R2 do not affect R1's static route next-hop reachability; the issue is on R1.
- B
Increase the static route's preference to a lower value (e.g., 4).
Why wrong: Incorrect: the default preference of 5 is already very low; a lower preference would not help because the route is hidden, not competing with another route.
- C
Configure a more specific static route to 172.16.10.0/24 with a mask of /25.
Why wrong: Incorrect: a more specific route would still have the same next-hop and would also be hidden if the next-hop is unreachable.
- D
Check if the next-hop IP 192.168.1.2 is reachable via the directly connected interface.
Correct: the next-hop unreachability is the most common cause of a hidden static route; verifying reachability (e.g., ping, ARP) will identify the issue.
Quick Answer
The answer is to check if the next-hop IP 192.168.1.2 is reachable via the directly connected interface. A static route becomes hidden in Junos when the next-hop is not considered reachable at the IP level, even if a routing protocol like OSPF knows about the subnet containing that next-hop. The router performs a reachability check on the specific next-hop address, not just the prefix, so if the directly connected interface is down, an ARP entry is missing, or a firewall filter blocks traffic, the route will be hidden. On the JNCIA-Junos exam, this concept tests your understanding of how Junos validates static route next-hops before installing them in the forwarding table, a common trap where students assume OSPF knowledge of the subnet guarantees reachability. Remember the hidden route rule: the next-hop must be directly reachable via a connected interface, not just reachable through another route. A useful memory tip is “hidden means hop is homeless”—if the next-hop can’t ARP out its own interface, the route stays hidden.
JNCIA-JUNOS Routing Fundamentals Practice Question
This JNCIA-JUNOS practice question tests your understanding of routing fundamentals. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
You are a network engineer for a company that uses two Juniper routers, R1 and R2, connected via an Ethernet link. R1 and R2 are running OSPF in the same area, and R2 also has an eBGP session with a service provider to reach the internet. On R1, you have configured a static route to the subnet 172.16.10.0/24 with a next-hop of 192.168.1.2, which is the IP address of R2's interface facing R1. You have verified that the static route is configured correctly in the configuration, but traffic from R1 to 172.16.10.0/24 is not being forwarded. You check the routing table on R1 and see that the static route is present but marked as 'hidden'. You also notice that R1 has an OSPF-learned route to 192.168.1.0/30 (the link between R1 and R2) with a cost of 1. What is the most likely reason for the hidden static route?
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
Check if the next-hop IP 192.168.1.2 is reachable via the directly connected interface.
A static route becomes hidden when the next-hop is unreachable. Even though R1 has an OSPF route to the subnet containing the next-hop (192.168.1.0/30), the router checks reachability at the IP level. In this scenario, the next-hop 192.168.1.2 is directly connected and should be reachable via the OSPF route. However, the question states the static route is hidden, indicating the next-hop is not considered reachable. This can happen if there is a firewall filter or a security policy blocking ARP or if the interface is down. Option A is the most direct troubleshooting step. Option B is incorrect because the default preference of 5 is already low; increasing it would make the route less preferred. Option C is incorrect as the route is already specific. Option D is incorrect: disabling BGP would not affect the static route's next-hop reachability.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Disable the eBGP session on R2 to remove the BGP routes from the routing table.
Why it's wrong here
Incorrect: BGP routes on R2 do not affect R1's static route next-hop reachability; the issue is on R1.
- ✗
Increase the static route's preference to a lower value (e.g., 4).
Why it's wrong here
Incorrect: the default preference of 5 is already very low; a lower preference would not help because the route is hidden, not competing with another route.
- ✗
Configure a more specific static route to 172.16.10.0/24 with a mask of /25.
Why it's wrong here
Incorrect: a more specific route would still have the same next-hop and would also be hidden if the next-hop is unreachable.
- ✓
Check if the next-hop IP 192.168.1.2 is reachable via the directly connected interface.
Why this is correct
Correct: the next-hop unreachability is the most common cause of a hidden static route; verifying reachability (e.g., ping, ARP) will identify the issue.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
OSPF neighbours must agree on key parameters.
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
- OSPF neighbours must agree on key parameters.
- Router ID selection can affect neighbour relationships and LSDB output.
- OSPF cost influences the preferred path.
- A route can appear in OSPF information but not become the installed route.
TExam Day Tips
- Check area mismatch first when OSPF adjacency fails.
- Review passive interfaces when a network is advertised but no neighbour forms.
- Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
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.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related JNCIA-JUNOS OSPF questions on adjacency and route selection.
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FAQ
Questions learners often ask
What does this JNCIA-JUNOS question test?
Routing Fundamentals — This question tests Routing Fundamentals — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: Check if the next-hop IP 192.168.1.2 is reachable via the directly connected interface. — A static route becomes hidden when the next-hop is unreachable. Even though R1 has an OSPF route to the subnet containing the next-hop (192.168.1.0/30), the router checks reachability at the IP level. In this scenario, the next-hop 192.168.1.2 is directly connected and should be reachable via the OSPF route. However, the question states the static route is hidden, indicating the next-hop is not considered reachable. This can happen if there is a firewall filter or a security policy blocking ARP or if the interface is down. Option A is the most direct troubleshooting step. Option B is incorrect because the default preference of 5 is already low; increasing it would make the route less preferred. Option C is incorrect as the route is already specific. Option D is incorrect: disabling BGP would not affect the static route's next-hop reachability.
What should I do if I get this JNCIA-JUNOS question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related JNCIA-JUNOS OSPF questions on adjacency and route selection.
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?
OSPF neighbours must agree on key parameters.
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Same concept, more angles
1 more ways this is tested on JNCIA-JUNOS
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. An engineer configures a static route to 192.168.0.0/16 with next-hop 172.16.1.1. The router has a directly connected route for 172.16.1.0/30 via interface ge-0/0/0.1. However, the static route appears as 'hidden' in the routing table. What is the most likely cause?
medium- A.The static route preference is set too high
- ✓ B.The next-hop address 172.16.1.1 is unreachable
- C.The static route has not been committed
- D.The static route is a discard route
Why B: A hidden static route typically means the next-hop is not reachable. Option D correctly identifies this. Option A is incorrect because high preference does not cause hidden; it may not be active but still visible. Option B is incorrect because a discard route would be flagged as 'discard'. Option C is incorrect because the route is committed if it appears in the configuration.
Last reviewed: Jun 24, 2026
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