JN0-106 Operational Monitoring and Maintenance Practice Question
An administrator is asked to check the system log files for any error messages related to interface failures. Which command would be most efficient?
⚠ Common exam trap
Many exam-takers confuse 'monitor start messages' with 'show log messages', thinking the real-time monitor is more efficient for checking logs, but the question asks for checking existing log files, not monitoring live events.
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' is the standard JUNOS command to display the contents of the /var/log/messages file. While it does not include a filter, it is the only valid command among the options that allows the administrator to view existing system log messages. The other options are either invalid commands (B and D) or used for real-time monitoring (A), which is not efficient for checking historical log files.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
monitor start messages | match "error"
Why it's wrong here
monitor start messages | match "error" — This command enters real-time monitoring mode, tailing the messages log file and displaying new entries as they are written. It does not show the historical contents of the file, which is what an administrator would need when checking system log files. The match filter only applies to the live stream, so it cannot be used to review existing log entries. Therefore, it is unsuitable for this task.
- ✗
show log file messages | match "error"
Why it's wrong here
show log file messages | match "error" — The Junos CLI does not recognize the 'file' keyword in this context. The correct syntax is 'show log <filename>', e.g., 'show log messages'. Including 'file' between 'log' and 'messages' makes the command invalid; Junos will return an error or interpret 'file' as a filename itself, which does not exist. Even with a match filter, this command cannot function as intended because the base syntax is wrong. So it is not a valid way to check the log.
- ✓
show log messages
Why this is correct
show log messages — This is the correct operational command to display the contents of the default system log file /var/log/messages. It shows all messages stored in that file, providing the administrator with the historical log data needed. While it outputs everything without a match filter, it is the only valid command among the options that actually works for viewing existing log entries. Additional filtering could be applied with a pipe, e.g., 'show log messages | match error', but the base command is sufficient.
- ✗
show system syslog messages
Why it's wrong here
show system syslog messages — This command is not valid in Junos. Junos offers 'show log messages' to view the syslog file, and 'show system messages' to display recent event messages, but there is no 'show system syslog messages' operation. Attempting to run it results in a syntax error, as the CLI does not recognize 'syslog' as a subcommand under 'show system'. Therefore, it cannot be used to check system log files.
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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.