JN0-106 User Interfaces Practice Question
A technician wants to view the system log messages in real time. Which command should they use?
⚠ Common exam trap
The trap here is that candidates familiar with Cisco IOS might expect 'show log' or 'show logging' to provide real-time output, but in Junos, 'show log messages' only shows the static file, while 'monitor start messages' is the live tail command.
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
✓
monitor start messages
The 'monitor start messages' command is used in Junos OS to display system log messages in real time as they are generated. This is the correct command for live monitoring of system events, similar to 'tail -f' on Unix systems.
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 system log
Why it's wrong here
In Junos, there is no operational command 'show system log'. Junos uses the 'show log' command to display log file contents, and 'monitor start' to follow log files in real time. Typing 'show system log' returns a syntax error because the CLI expects a valid show command, not a non-existent combination of 'system' and 'log'.
- ✓
monitor start messages
Why this is correct
This is the correct command. It continuously outputs new lines appended to the /var/log/messages file, effectively 'tailing' the log in real time, until you cancel it with Ctrl-C or issue 'monitor stop'. It's the operational-mode command designed specifically for live log monitoring on Junos.
- ✗
start shell
Why it's wrong here
While 'start shell' drops you into a Unix-like shell on the device, it is not a log-viewing command and does not automatically show system log messages. From that shell you could manually run commands like 'tail -f /var/log/messages', but that bypasses the Junos CLI and is neither the intended nor the standard way to monitor logs. It also requires shell access permissions and is not the correct answer to the question.
- ✗
show log messages
Why it's wrong here
This command displays the existing contents of the /var/log/messages log file and then exits, showing no live or real-time updates. It gives you a point-in-time snapshot, not the continuous stream of new messages that 'monitor start messages' provides. Use 'monitor start messages' when you need to watch log messages as they are generated.
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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.