JN0-106 Networking Fundamentals Practice Question
A company uses a Juniper MX router to connect two branch offices via a point-to-point link. The link is flapping. Which command would you use to check the interface errors on the link?
⚠ Common exam trap
It's easy for candidates to choose 'show interfaces terse' thinking it shows errors, but it only displays administrative and operational status without the detailed error statistics needed to diagnose flapping.
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 interfaces ge-0/0/0 extensive
The 'show interfaces ge-0/0/0 extensive' command provides detailed interface statistics, including error counters such as CRC errors, frame errors, and link state transitions. This is the most comprehensive command to diagnose why a point-to-point link is flapping, as it reveals physical-layer issues that cause the interface to go up/down repeatedly.
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 log messages
Why it's wrong here
show log messages is for examining the system logging facility, which records events such as interface transitions or error alerts. However, it does not provide a consolidated, cumulative view of interface error counters; it only shows individual log entries at the time they occurred. Even if an error is logged, you cannot use that output to see current counts of CRC errors, drops, or framing errors, so it's not the right tool for this task.
- ✓
show interfaces ge-0/0/0 extensive
Why this is correct
show interfaces ge-0/0/0 extensive outputs the full operational status of the physical and logical interface, including detailed input/output error counters, CRC errors, framing errors, and packet drops. This command displays both current and cumulative statistics, allowing an administrator to identify the specific type and magnitude of interface errors. Because the goal is to check for errors on that interface, extensive is the correct command to run.
- ✗
show configuration interfaces ge-0/0/0
Why it's wrong here
show configuration interfaces ge-0/0/0 displays only the configuration hierarchy from the configuration database, such as family settings, unit numbers, and interface properties. It conveys nothing about live operational state or real-time error counters, since those values exist only in the operational datastore and are not stored as configuration statements. Configuration output cannot reveal CRC or framing errors, so this command is wrong for an operational troubleshooting task.
- ✗
show interfaces ge-0/0/0 terse
Why it's wrong here
show interfaces ge-0/0/0 terse provides a condensed, one-line-per-unit summary showing only administrative and operational status, such as link up/down and protocol state. It does not include error counters, packet statistics, or queue information, so it cannot reveal issues like CRC errors or drops. Terse format is meant for a quick high-level overview, not for detailed per-interface fault analysis, which is why it is not the correct choice.
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.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This JN0-106 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 JN0-106 exam.