JN0-106 Junos OS Fundamentals Practice Question
An engineer suspects that a recent software upgrade caused a compatibility issue. Which command should be used to revert the Junos OS to the previous version?
⚠ Common exam trap
Test-takers frequently confuse 'rollback' in the context of configuration management (rollback 0) with software version rollback, leading candidates to mistakenly choose option A.
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
✓
request system software rollback
The 'request system software rollback' command is the correct method to revert the Junos OS to the previously installed version. This command triggers a reboot and loads the previous software set from the /altroot partition, effectively undoing the upgrade while preserving the configuration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
rollback 0
Why it's wrong here
The Junos 'rollback 0' command is a configuration rollback operation that reverts the candidate configuration to the most recently committed configuration. It discards uncommitted changes and restores the prior configuration state, but it has absolutely no effect on the Junos OS software image or the active software partition. Therefore, it cannot undo a software upgrade.
- ✓
request system software rollback
Why this is correct
The 'request system software rollback' command is the correct way to revert a Junos device to the previous operating system version after an upgrade. Junos maintains two software partitions (the current and previous), and this command marks the previous partition as the primary boot image, then reboots the device to activate that older version. This is the intended recovery mechanism when a recent upgrade causes problems.
- ✗
request system reboot
Why it's wrong here
The 'request system reboot' command simply restarts the device and loads the software partition that is currently marked as the primary boot image. If the upgraded software is already active and set as primary, a reboot will bring the system back to the same upgraded version, not the previous one. It does not select or activate a different software partition, so it cannot revert an upgrade.
- ✗
request system software delete jinstall-*.tgz
Why it's wrong here
The 'request system software delete jinstall-*.tgz' command removes the software package file from the device's storage, but it does not uninstall or deactivate the currently running software. The upgraded OS remains active in its dedicated software partition and will continue to be used on subsequent reboots. Deleting the package merely frees disk space; it does not cause a fallback to the previous Junos version.
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About these practice questions
Courseiva writes every JN0-106 question from scratch — 326 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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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.