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.
Exhibit
show route 10.0.0.0/24
inet.0: 5 destinations, 5 routes (4 active, 1 hold-down, 1 hidden)
10.0.0.0/24 (1 entry, 1 announced)
Static
Preference: 5
Next hop type: Unreachable via 192.168.1.1, route not installed
Refer to the exhibit. A network administrator configured a static route to 10.0.0.0/24 with next-hop 192.168.1.1. The route is not appearing in the active routing table. What is the most likely reason?
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
show route 10.0.0.0/24
inet.0: 5 destinations, 5 routes (4 active, 1 hold-down, 1 hidden)
10.0.0.0/24 (1 entry, 1 announced)
Static
Preference: 5
Next hop type: Unreachable via 192.168.1.1, route not installed
A
The next-hop address is not reachable.
Correct: the exhibit shows 'Next hop type: Unreachable', meaning 192.168.1.1 is not reachable, so the route is not installed.
B
The route is a reject route.
Why wrong: Incorrect: a reject route would have a next-hop of 'Reject' or 'Discard', not 'Unreachable'.
C
The route is being overridden by an OSPF route with lower preference.
Why wrong: Incorrect: if an OSPF route with a lower preference (e.g., 10) existed, it would be active, but the static route would still appear in the table as a backup; the exhibit shows the route is not active at all.
D
The static route preference is too high.
Why wrong: Incorrect: the default preference of 5 is low; routes with lower preference are preferred.
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 address is not reachable.
The exhibit shows that the route's next-hop type is 'Unreachable', indicating that the next-hop address 192.168.1.1 is not reachable. Since the next-hop is unreachable, the static route cannot be installed in the active routing table. Option B is incorrect because a reject route would show 'Reject' or 'Discard'. Option C is incorrect: even if an OSPF route existed with lower preference (higher priority), the static route would still appear as a backup; the problem here is next-hop unreachability. Option D is incorrect: a static route with preference 5 is low, meaning it is highly preferred; high preference would make it less preferred, but the route is not active due to unreachable next-hop, not preference.
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.
✓
The next-hop address is not reachable.
Why this is correct
Correct: the exhibit shows 'Next hop type: Unreachable', meaning 192.168.1.1 is not reachable, so the route is not installed.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Incorrect: a reject route would have a next-hop of 'Reject' or 'Discard', not 'Unreachable'.
✗
The route is being overridden by an OSPF route with lower preference.
Why it's wrong here
Incorrect: if an OSPF route with a lower preference (e.g., 10) existed, it would be active, but the static route would still appear in the table as a backup; the exhibit shows the route is not active at all.
✗
The static route preference is too high.
Why it's wrong here
Incorrect: the default preference of 5 is low; routes with lower preference are preferred.
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.
Trap categories for this question
Command / output trap
Incorrect: if an OSPF route with a lower preference (e.g., 10) existed, it would be active, but the static route would still appear in the table as a backup; the exhibit shows the route is not active at all.
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.
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.
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.
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: The next-hop address is not reachable. — The exhibit shows that the route's next-hop type is 'Unreachable', indicating that the next-hop address 192.168.1.1 is not reachable. Since the next-hop is unreachable, the static route cannot be installed in the active routing table. Option B is incorrect because a reject route would show 'Reject' or 'Discard'. Option C is incorrect: even if an OSPF route existed with lower preference (higher priority), the static route would still appear as a backup; the problem here is next-hop unreachability. Option D is incorrect: a static route with preference 5 is low, meaning it is highly preferred; high preference would make it less preferred, but the route is not active due to unreachable next-hop, not preference.
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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