View System Log Messages in Junos: Show Log and Monitor Start
Which TWO commands can be used to view the system log messages on a Juniper device? (Select two.)
Quick Answer
The correct answer is that both the 'show log messages' and 'monitor start messages' commands are used to view system log messages on a Juniper device. The 'show log messages' command reads and displays the static contents of the default system log file, /var/log/messages, which stores kernel, daemon, and system-level events, making it ideal for historical review. In contrast, 'monitor start messages' provides a real-time tail of the same file, allowing you to watch live log entries as they are written, which is essential for troubleshooting ongoing issues. On the JNCIA-Junos exam, this question tests your understanding of Junos operational commands for system monitoring, and a common trap is confusing 'show log' with 'show log messages'—the former requires a specific filename, while the latter defaults to /var/log/messages. A helpful memory tip is to think of 'show' as a snapshot of the past and 'monitor start' as a live feed, just like the difference between reading a book and watching a live stream.
⚠ Common exam trap
A common mix-up: candidates confuse the generic 'show log' syntax with a nonexistent 'show log file' command, or they mistakenly think 'show system messages' is valid because of similarity to other vendors' commands like 'show logging' on Cisco IOS.
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 log messages
'show log messages' displays the contents of the default system log file, /var/log/messages, which contains kernel, daemon, and system-level messages. Option C is correct because 'monitor start messages' provides a real-time tail of the same /var/log/messages file, allowing live monitoring of system log entries as they are written.
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 dcd
Why it's wrong here
Shows a specific log, not the main messages.
- ✓
show log messages
Why this is correct
Displays and tails the current log messages.
- ✓
monitor start messages
Why this is correct
Tails live log messages.
- ✗
show log file
Why it's wrong here
Not a standard command; usually specifies a file.
- ✗
show system messages
Why it's wrong here
Not a valid command.
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About these practice questions
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Same concept, more angles
1 more way 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. Which TWO commands can be used to monitor system log messages in real-time?
medium- A.show log messages | last 100
- B.show system log messages
- C.show configuration system syslog
- D.monitor start interactive-commands
- ✓ E.monitor start messages
Why E: The 'monitor start messages' command streams the contents of the /var/log/messages file in real-time, allowing you to monitor system log messages as they are generated. 'monitor start interactive-commands' (Option D) monitors logs specific to interactive CLI commands, not general system log messages, so it does not satisfy the stem. The other options ('show log messages | last 100', 'show system log messages', 'show configuration system syslog') either display historical data or configuration, not real-time system log monitoring.
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.