Quick Answer
The answer is that the OSPF interface is configured as passive. The passive statement under the OSPF interface configuration prevents the router from sending or processing OSPF Hello packets on ge-0/0/1.0, which directly blocks neighbor discovery and adjacency formation, explaining why the show ospf neighbor command returns no neighbors despite the interface being operationally up. On the JNCIA-Junos exam, this scenario tests your understanding of how OSPF passive interfaces suppress Hello traffic, a common trap where candidates assume a physically up interface guarantees OSPF adjacency. The passive keyword is often misapplied to loopbacks or stub networks, but here it mistakenly silences a point-to-point link. Remember the memory tip: “Passive means no packets, no neighbors, no adjacency.”
This JNCIA-JUNOS practice question tests your understanding of operational monitoring and maintenance. 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 troubleshooting an OSPF issue on a Juniper router. The router has a single interface ge-0/0/1 with IP 10.1.1.1/30 connected to a neighbor with IP 10.1.1.2/30. OSPF is configured area 0. The 'show ospf neighbor' command shows no neighbors. 'show interfaces ge-0/0/1 terse' shows the interface is up. 'show configuration protocols ospf' shows:
area 0.0.0.0 {
interface ge-0/0/1.0 {passive;
} }
What is the problem?
The OSPF interface is configured as passive
Passive interfaces do not send hellos.
The hello timer is too slow
Why wrong: No hello configured due to passive.
Authentication is missing
Why wrong: Not required.
The interface is administratively down
Why wrong: Interface is up per terse output.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The OSPF interface is configured as passive
The 'passive' statement under the OSPF interface configuration prevents the router from sending or processing OSPF Hello packets on that interface. Without Hello packets, the router cannot discover neighbors or form adjacencies, which is why 'show ospf neighbor' returns no neighbors even though the interface is operationally up.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The OSPF interface is configured as passive
Why this is correct
Passive interfaces do not send hellos.
Related concept
Read the scenario before looking for a memorised answer.
The hello timer is too slow
Why it's wrong here
No hello configured due to passive.
Authentication is missing
Why it's wrong here
Not required.
The interface is administratively down
Why it's wrong here
Interface is up per terse output.
Common exam traps
The trap here is that candidates often assume 'passive' only prevents the interface from sending routing updates (like in RIP or EIGRP), but in OSPF it blocks all Hello packets, preventing neighbor discovery entirely.
Trap categories for this question
Command / output trap
Interface is up per terse output.
Detailed technical explanation
When an OSPF interface is configured as passive, the router suppresses all OSPF protocol packets (Hello, DBD, LSR, LSU, LSAck) on that interface, effectively treating it as a stub network. This is commonly used for loopback interfaces or to reduce OSPF overhead on links where no adjacencies are needed, but it will completely block neighbor discovery on that interface.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Operational Monitoring and Maintenance — This question tests Operational Monitoring and Maintenance — Read the scenario before looking for a memorised answer..
The correct answer is: The OSPF interface is configured as passive — The 'passive' statement under the OSPF interface configuration prevents the router from sending or processing OSPF Hello packets on that interface. Without Hello packets, the router cannot discover neighbors or form adjacencies, which is why 'show ospf neighbor' returns no neighbors even though the interface is operationally up.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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.
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