- A
show route protocol ospf
Why wrong: This command shows only active routes, not necessarily all received routes.
- B
show ospf neighbor
Why wrong: This command shows OSPF neighbor states, not received routes.
- C
show ospf database
This command shows LSAs in the OSPF database, including received routes.
- D
show interface terse
Why wrong: This command shows interface status, not routing information.
Question 108 of 514
Checking OSPF Received Routes
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.
A network administrator is troubleshooting a missing route in the routing table. The route is learned via OSPF, and the OSPF neighbor adjacency is up. Which command would help determine if OSPF received the route?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"which command"Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Quick Answer
The answer is the show ospf database command, because it displays the link-state advertisements (LSAs) that OSPF has received from its neighbors, directly revealing whether a specific route has been learned. When troubleshooting a missing route with an established OSPF adjacency, the issue often lies in the LSA exchange rather than neighbor reachability, and this command lets you check OSPF received routes via database contents. On the JNCIA-Junos exam, this question tests your understanding that OSPF maintains a separate link-state database from the routing table, and that a neighbor being up does not guarantee a route is present. A common trap is to choose show ospf neighbor, which only confirms adjacency status, or show route, which shows only active routes already installed. Remember the memory tip: “Database before route” — always verify the LSA in the OSPF database first to confirm the route was received, before checking if it was installed.
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
✓
show ospf database
Option C is correct because the OSPF link-state database (LSDB) contains all received LSAs, including Type 1 (Router) and Type 3 (Summary) LSAs that advertise routes. Even if a route is not installed in the routing table (e.g., due to a higher administrative distance or a missing route preference), the 'show ospf database' command confirms whether OSPF has received the LSA carrying that route. This directly answers the question of whether OSPF received the route, independent of route installation.
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.
- ✗
show route protocol ospf
Why it's wrong here
This command shows only active routes, not necessarily all received routes.
- ✗
show ospf neighbor
Why it's wrong here
This command shows OSPF neighbor states, not received routes.
- ✓
show ospf database
Why this is correct
This command shows LSAs in the OSPF database, including received routes.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
show interface terse
Why it's wrong here
This command shows interface status, not routing information.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'show route protocol ospf' (which shows installed routes) with 'show ospf database' (which shows received LSAs), leading them to pick option A when the route is missing from the routing table but still present in the LSDB.
Trap categories for this question
Command / output trap
This command shows only active routes, not necessarily all received routes.
Detailed technical explanation
How to think about this question
OSPF uses a link-state database (LSDB) that is synchronized between neighbors; each router floods LSAs (e.g., Router LSA, Network LSA, Summary LSA) to describe its links and prefixes. The 'show ospf database' command displays the LSDB, allowing an administrator to see all received LSAs, including those that may not be installed in the routing table due to route selection rules (e.g., OSPF external routes with a higher metric or a preference override). In real-world scenarios, this command is critical for troubleshooting OSPF route propagation issues, such as when a route is missing due to a missing LSA or a filtering policy like a route-map that suppresses the route from being installed.
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.
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.
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FAQ
Questions learners often ask
What does this JNCIA-JUNOS question test?
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: show ospf database — Option C is correct because the OSPF link-state database (LSDB) contains all received LSAs, including Type 1 (Router) and Type 3 (Summary) LSAs that advertise routes. Even if a route is not installed in the routing table (e.g., due to a higher administrative distance or a missing route preference), the 'show ospf database' command confirms whether OSPF has received the LSA carrying that route. This directly answers the question of whether OSPF received the route, independent of route installation.
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: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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