JN0-106 Junos OS Fundamentals Practice Question
An administrator needs to quickly revert all uncommitted configuration changes and return the device to the last committed configuration. Which command accomplishes this?
⚠ Common exam trap
Many exam-takers confuse 'rollback 0' with 'rollback 1', mistakenly thinking rollback 1 reverts to the last committed configuration, when in fact rollback 0 is the correct index for the most recent commit, and rollback 1 refers to the configuration before that.
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 command 'rollback 0' reverts all uncommitted configuration changes and returns the device to the last committed configuration. In Junos, the rollback command uses a numeric argument to specify which previous configuration to load, with 0 always referring to the most recently committed configuration. This effectively discards any pending changes in the candidate configuration without requiring a commit.
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 this is correct
The correct way to quickly discard all uncommitted changes in the candidate configuration is to execute 'rollback 0' in configuration mode. This operation overwrites the candidate configuration with the contents of the most recent committed configuration, effectively resetting any modifications made since the last commit. It is the fastest method because it does not require a reboot or additional file operations, and you can verify the change by entering 'show configuration' to confirm the candidate now matches the active configuration.
- ✗
delete configuration
Why it's wrong here
'delete configuration' is not a recognized command in Junos. Junos uses configuration mode commands such as 'delete interfacename' or 'set' to modify specific configuration statements, but there is no single command to delete the entire running configuration in one step. The only valid way to revert to a previous state is to use rollback, which is an operational mode command for configuration management.
- ✗
load override
Why it's wrong here
The 'load override' command is designed to load a complete configuration from a file or URL, replacing the entire candidate configuration with the contents of that saved configuration file. It will not automatically revert to the last committed configuration unless you happen to have saved that exact configuration to a file, which is not the typical scenario for discarding uncommitted changes. This command is useful for restoring a known-good configuration from an archive, but it does not serve the same purpose as a quick rollback.
- ✗
rollback 1
Why it's wrong here
'rollback 1' reverts the candidate configuration to the configuration that existed at the previous commit, which is the commit before the current active configuration. If you have uncommitted changes on top of the current committed config, rolling back to 1 would bring back an older configuration and discard the current committed state, which is not what you want. Only 'rollback 0' targets the actual active configuration and is the correct choice for discarding uncommitted changes without altering the last committed state.
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.