JN0-106 Operational Monitoring and Maintenance Practice Question
Which THREE operational commands are used to monitor interface statistics and status? (Select three.)
⚠ Common exam trap
It's easy for candidates to confuse 'show log interfaces' with the valid 'show log' command or mistakenly think 'show interfaces diagnostics' is a catch-all command, when in reality Junos requires specific sub-commands like 'show interfaces diagnostics optics' for optics monitoring.
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 terse
Option A, "show interfaces terse," is correct because it provides a compact, one-line-per-interface summary of operational status (up/down), protocol state, and basic counters, making it ideal for quickly monitoring interface status. Option B, "monitor interface," is correct because it displays real-time, continuously updating interface statistics and status, which is specifically designed for live monitoring of interface traffic and errors. Option C, "show interfaces," is correct because it gives detailed operational output including status, protocol state, error counters, and statistics for each interface, serving as a primary monitoring command. Option D, "show log interfaces," is not a valid operational command for monitoring interface statistics and status; logs are viewed with commands like "show log messages." Option E, "show interfaces diagnostics," is not a standard command for monitoring interface statistics and status; diagnostics commands typically display optics or hardware diagnostic information rather than general interface status and counters.
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 this is correct
The 'show interfaces terse' command is a compact operational mode command that lists every interface on a single line, displaying the administrative and link status, protocol status, and configured IP addresses. It is ideal for quickly determining which interfaces are up or down, and is often used in scripts to capture a high-level snapshot of interface state.
- ✓
monitor interface
Why this is correct
The 'monitor interface' command provides a real-time, continuously updating view of interface statistics, including traffic rates, error counts, and packet counts, refreshing at a configurable interval (e.g., every 1 second). It is useful during live troubleshooting to observe traffic patterns or detect intermittent errors that a one-time snapshot might miss, and it requires the user to press Ctrl+C to exit.
- ✓
show interfaces
Why this is correct
The 'show interfaces' command (without modifiers) displays detailed, one-time statistics for all interfaces, including forwarding error counters, packet and byte counts, queue depths, MTU, and current conditions such as link state and speed. It gives an in-depth snapshot at a particular moment, suitable for detailed analysis but not for continuous monitoring.
- ✗
show log interfaces
Why it's wrong here
'show log interfaces' is not a valid Junos operational command. In Junos, log files are accessed using 'show log <filename>', with common files like 'messages', 'chassisd', or 'interactive-commands'; the keyword 'interfaces' is not a predefined log filename. The interface traceoptions logs are written to a specified file (e.g., 'show log interface-trace'), but the syntax 'show log interfaces' itself will fail.
- ✗
show interfaces diagnostics
Why it's wrong here
The 'show interfaces diagnostics' command is specifically designed to display optics-related diagnostics for interfaces that have pluggable optical transceivers (e.g., SFP, XFP), such as optical TX/RX power, temperature, and bias current—not general interface statistics like packet counters or errors. It is useful for verifying optical health, but it does not provide the interface status and traffic information that monitoring tasks typically require.
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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.