Monitor Interface in Junos: Real-Time Statistics and Errors
Which two commands can be used to monitor real-time interface statistics and errors on a Junos device?
Quick Answer
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.
⚠ Common exam trap
A common mix-up: candidates 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.
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 extensive ge-0/0/0 | refresh 1
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.
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.
- ✓
monitor interface ge-0/0/0
Why this is correct
Displays real-time interface statistics and errors, updated continuously.
- ✗
monitor security log
Why it's wrong here
Used for monitoring security events, not interface statistics.
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Same concept, more angles
2 more ways this is tested on JN0-106
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.
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.