Junos Commit Operations: commit confirmed, commit check, and rollback
Which THREE statements are true about commit operations in Junos OS?
Quick Answer
The correct answer is that the 'commit confirmed' command allows a rollback to the previous configuration if not confirmed within the timeout period. This is true because Junos OS serializes commit operations: while multiple users can enter configuration mode and make changes simultaneously, only one commit can be processed at a time, preventing conflicting updates from being applied concurrently. On the JNCIA-Junos exam, this concept tests your understanding of Junos commit operations advanced behavior, particularly how the system ensures configuration consistency in multi-user environments. A common trap is assuming that multiple users can commit at the same time, but the serialized commit model means each user must wait their turn. For the 'commit confirmed' command, remember that it automatically triggers a rollback if the timer expires, making it ideal for risky changes. Memory tip: think of "confirmed" as a safety net—if you don't confirm in time, the net catches you and pulls you back to the previous configuration.
⚠ Common exam trap
Candidates often confuse 'commit confirmed' with an immediate discard of changes, when in fact it temporarily activates the configuration and only rolls back if the confirmation is not received within the timeout period.
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
✓
Multiple users can make configuration changes simultaneously, but only one can commit at a time.
Junos OS allows multiple users to enter configuration mode and make changes simultaneously, but the commit operation is serialized: only one user can commit at a time. This prevents conflicting changes from being applied concurrently, ensuring configuration consistency.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The 'commit confirmed' command immediately discards changes if not confirmed.
Why it's wrong here
It schedules a rollback; changes are not immediately discarded.
- ✓
Multiple users can make configuration changes simultaneously, but only one can commit at a time.
Why this is correct
Junos uses a lock to serialize commits.
- ✓
The 'commit check' command validates the configuration syntax without activating it.
Why this is correct
'commit check' verifies syntax and semantics without committing.
- ✓
The 'commit confirmed' command allows a rollback to the previous configuration if not confirmed within the timeout period.
Why this is correct
This is the purpose of 'commit confirmed'.
- ✗
The 'commit' command always requires 'commit synchronize' when using dual Routing Engines.
Why it's wrong here
'commit synchronize' is used only when you want to synchronize configurations; 'commit' alone commits only on the local RE.
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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 statements about the Junos commit model are true?
medium- ✓ A.A commit makes the candidate configuration the active configuration.
- B.The commit command is used to discard changes.
- ✓ C.The rollback command can be used to revert to a previous configuration.
- D.A commit validation is performed automatically before commit.
- E.Multiple candidates can be active simultaneously.
Why A: The Junos commit model uses a two-phase process: changes are made to the candidate configuration, and the `commit` command activates that candidate configuration as the new active configuration. This ensures that changes are not applied until explicitly committed, providing a safe and predictable way to modify the device's operational state.
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.