JN0-106 Junos OS Fundamentals Practice Question
A network administrator makes several changes to the configuration but decides to discard all uncommitted changes and start fresh. Which command should be used to revert the candidate configuration back to the current active configuration?
⚠ Common exam trap
Many candidates confuse 'rollback 0' with 'rollback 1', mistakenly thinking that 'rollback 1' discards uncommitted changes, when in fact 'rollback 1' reverts to the previous committed configuration, which would undo the last commit and potentially cause service disruption.
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
✓
rollback 0
The 'rollback 0' command reverts the candidate configuration to the currently active configuration, discarding all uncommitted changes. This is because Junos maintains a rollback database of the last 50 committed configurations, with index 0 always representing the active configuration. Using 'rollback 0' effectively resets the candidate configuration to match the active one, allowing the administrator to start fresh without affecting the running system.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
load override
Why it's wrong here
load override loads a configuration from an external file into the candidate configuration, completely replacing its contents. It does not reference the current committed configuration unless you explicitly specify a file containing that exact config. In the scenario of discarding uncommitted edits, load override would overwrite the candidate with the file's contents, not with the active config, so it cannot serve as a rollback to the current committed state. Without a suitable file, it is the wrong operation.
- ✓
rollback 0
Why this is correct
rollback 0 discards all uncommitted changes and reloads the candidate configuration to exactly match the current committed (active) configuration. The index 0 always points to the most recent commit, so this operation cleans the candidate without altering the running configuration. Since the administrator simply wants to start fresh from the last committed state, rollback 0 is the precise command. Note that you still must issue a commit to make any further changes active, but no commit is required to just discard edits.
- ✗
commit check
Why it's wrong here
commit check performs a validation pass on the candidate configuration, checking syntax, variable references, and system constraints, but it applies no changes. If the candidate is valid, it returns success and leaves all uncommitted edits exactly as they were. This command is useful for verifying a configuration before committing, but it does not discard anything or reset the candidate. Therefore, commit check cannot roll back uncommitted changes; it only reports whether they would be accepted.
- ✗
rollback 1
Why it's wrong here
rollback 1 loads the configuration from the previous commit (the commit before the current one) into the candidate, not the current committed configuration. The rollback index counts backward from 0, so 1 references a snapshot that may lack changes made in the last commit. Using rollback 1 would replace the candidate with that older state, discarding the current active configuration from the candidate while also failing to simply remove uncommitted edits. It is wrong because the administrator needs index 0, not index 1.
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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.