The correct commands are monitor interface ge-0/0/0 and show interfaces extensive ge-0/0/0 | refresh 1, as both provide real-time interface statistics and errors on a Junos device. The monitor interface command is purpose-built for live tracking, automatically refreshing interface counters like input/output packets, drops, and CRC errors every second by default, while the show interfaces extensive command combined with the refresh 1 pipe modifier achieves the same effect by forcing a one-second update cycle. On the JNCIA-Junos exam, this topic tests your ability to distinguish between static show commands and dynamic monitoring tools, often appearing in questions about operational monitoring or troubleshooting link issues. A common trap is confusing the standard show interfaces command, which gives a single snapshot, with the real-time variants; remember that without refresh or the monitor keyword, you are not seeing live data. For a quick memory tip, think “monitor for motion, show for a photo” — the monitor command keeps the screen moving with fresh statistics, while show captures a static moment.
JNCIA-JUNOS Operational Monitoring and Maintenance Practice Question
This JNCIA-JUNOS practice question tests your understanding of operational monitoring and maintenance. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
Which two commands can be used to monitor real-time interface statistics and errors on a Junos device?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
show interfaces extensive ge-0/0/0 | refresh 1
Option C is correct because the 'show interfaces extensive ge-0/0/0 | refresh 1' command displays detailed interface statistics and errors, and the 'refresh 1' pipe modifier automatically updates the output every second, enabling real-time monitoring. Option D is correct because the 'monitor interface ge-0/0/0' command is specifically designed for real-time monitoring of interface counters and errors, refreshing the display at a default interval of 1 second. Both commands provide live views of interface statistics such as input/output packets, errors, drops, and CRC errors.
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 interfaces terse
Why it's wrong here
Shows only a brief summary of interface status, not detailed statistics.
✗
show interfaces ge-0/0/0
Why it's wrong here
Shows a single snapshot of interface statistics, not continuous real-time monitoring.
✓
show interfaces extensive ge-0/0/0 | refresh 1
Why this is correct
With the refresh pipe option, it provides continuous updates of extensive interface statistics.
Related concept
Read the scenario before looking for a memorised answer.
✓
monitor interface ge-0/0/0
Why this is correct
Displays real-time interface statistics and errors, updated continuously.
Related concept
Read the scenario before looking for a memorised answer.
✗
monitor security log
Why it's wrong here
Used for monitoring security events, not interface statistics.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse static 'show interfaces' commands (which provide a point-in-time snapshot) with real-time monitoring commands, leading them to select option B instead of the correct real-time options C and D.
Trap categories for this question
Command / output trap
Shows only a brief summary of interface status, not detailed statistics.
Detailed technical explanation
How to think about this question
The 'monitor interface' command uses the Junos kernel to poll interface counters at a configurable interval (default 1 second) and displays delta values, making it ideal for spotting transient errors like CRC errors or packet drops. The 'refresh' pipe modifier works by appending a system call that re-executes the preceding command at the specified interval, which can be used with any 'show' command to simulate real-time monitoring. In real-world scenarios, these commands are essential for troubleshooting intermittent interface issues, such as flapping links or increasing error counters during traffic bursts.
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 practitioner preparing for the JNCIA-JUNOS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Operational Monitoring and Maintenance — This question tests Operational Monitoring and Maintenance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: show interfaces extensive ge-0/0/0 | refresh 1 — Option C is correct because the 'show interfaces extensive ge-0/0/0 | refresh 1' command displays detailed interface statistics and errors, and the 'refresh 1' pipe modifier automatically updates the output every second, enabling real-time monitoring. Option D is correct because the 'monitor interface ge-0/0/0' command is specifically designed for real-time monitoring of interface counters and errors, refreshing the display at a default interval of 1 second. Both commands provide live views of interface statistics such as input/output packets, errors, drops, and CRC errors.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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. To monitor interface traffic in real-time, which operational command is most appropriate?
easy
A.show interface traffic
B.request system reboot
C.show log
✓ D.monitor interface
Why D: The 'monitor interface' command in Junos provides real-time, continuous display of interface statistics and traffic counters, updating every second by default. This is the correct operational command for live traffic monitoring, as it refreshes the output dynamically without requiring manual re-entry.
Variation 2. Which two commands can be used to display real-time interface information? (Choose two.)
easy
✓ A.monitor interface
✓ B.monitor traffic
C.show log
D.request system reboot
E.show system storage
Why A: The `monitor interface` command provides a real-time, continuously updating view of interface statistics, including traffic counters, errors, and operational status. The `monitor traffic` command captures and displays live packet headers or full packets on an interface, useful for real-time traffic analysis. Both commands are designed for live monitoring, unlike static `show` commands or administrative actions.
Last reviewed: Jun 24, 2026
Question Discussion
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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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