JN0-106 User Interfaces Practice Question
A network engineer needs to commit a configuration change but wants to ensure the change can be easily reverted if it causes issues. Which approach should the engineer take?
⚠ Common exam trap
Many candidates confuse 'commit check' (syntax validation) with a rollback mechanism, or assume 'rollback 0' provides automatic reversion, when in fact it requires manual execution after the fact.
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
✓
Use the 'commit confirmed' command with a timeout.
The 'commit confirmed' command allows the engineer to commit a configuration change with a default timeout of 10 minutes (configurable). If the change causes issues and the engineer does not confirm the commit within the timeout period, Junos automatically reverts to the previous active configuration, providing a safe rollback mechanism.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use the 'commit and-quit' command to apply changes.
Why it's wrong here
The 'commit and-quit' command commits the candidate configuration and immediately exits configuration mode, but it does not schedule any rollback. If the change disrupts access, the device will retain the new config until a human manually intervenes. Unlike 'commit confirmed', it offers no safety net for remote administrators who might get locked out.
- ✓
Use the 'commit confirmed' command with a timeout.
Why this is correct
The 'commit confirmed' command with a timeout (e.g., 'commit confirmed 5') activates the configuration for a temporary interval, defaulting to 10 minutes. If the administrator does not issue a confirming 'commit' before the timer expires, Junos automatically rolls back to the previous configuration. This self-reverting behavior prevents permanent lockouts caused by misconfigured access settings.
- ✗
Use the 'commit check' command before committing.
Why it's wrong here
'commit check' validates the syntax and logical semantics of the candidate configuration without activating it. Passing the check does not guarantee the change is safe, and after a normal subsequent commit there is no automatic rollback available. It is a pre-flight validation tool, not a safeguard against unsuccessful remote changes.
- ✗
Use the 'rollback 0' command after committing.
Why it's wrong here
'rollback 0' in configuration mode loads the currently committed configuration as the candidate, effectively discarding uncommitted changes. After a commit, using 'rollback 0' then committing would manually revert to the previous config, but this requires outside access and does not happen automatically on a timeout. It is a manual recovery tool, not an automatic confirm mechanism.
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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.