Quick Answer
The answer is rollback 0, as this command discards all uncommitted changes and reverts the candidate configuration to the last committed configuration on a Juniper device. In Junos, the rollback command uses a numeric index where 0 always refers to the most recently committed configuration, effectively undoing any uncommitted edits made since that point. This concept is frequently tested on the JNCIA-Junos exam, often in the context of candidate configuration management, where a common trap is confusing rollback 0 with higher rollback numbers that revert to older committed configurations rather than the latest one. A useful memory tip is to think of 0 as the "zero point" or starting line after a commit—rolling back to 0 brings you right back to that last saved state, wiping out any uncommitted work in progress.
This JNCIA-JUNOS practice question tests your understanding of junos configuration basics. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A Juniper device has multiple candidate configurations loaded. The administrator wants to discard all uncommitted changes and revert to the last committed configuration. Which command should be used?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
rollback 0
Reverts the candidate configuration to the last committed one.
delete configuration
Why wrong: Incorrect; would delete configuration files.
clear configuration
Why wrong: Not a valid Junos command.
load override terminal
Why wrong: Loads configuration from terminal, does not revert.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
rollback 0
Option A is correct because the 'rollback 0' command reverts the candidate configuration to the last committed configuration, discarding all uncommitted changes. In Junos, the rollback command uses a numeric index where 0 always refers to the most recently committed configuration, effectively undoing any uncommitted edits.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
rollback 0
Why this is correct
Reverts the candidate configuration to the last committed one.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
delete configuration
Why it's wrong here
Incorrect; would delete configuration files.
clear configuration
Why it's wrong here
Not a valid Junos command.
load override terminal
Why it's wrong here
Loads configuration from terminal, does not revert.
Common exam traps
The trap here is that candidates may confuse 'rollback 0' with 'rollback 1', thinking 0 means 'no rollback' or that a higher number is needed to revert changes, when in fact 0 discards uncommitted edits and 1 reverts the last commit.
Trap categories for this question
Command / output trap
Not a valid Junos command.
Detailed technical explanation
Junos maintains a history of committed configurations (up to 50 by default) accessible via 'rollback <n>', where 0 is the most recent commit, 1 is the previous, etc. The 'rollback 0' command effectively undoes all uncommitted changes by copying the last committed configuration into the candidate configuration, which is then ready for a new commit. This is distinct from 'rollback 1' which reverts to the configuration before the last commit, useful for recovering from a bad commit.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the JNCIA-JUNOS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Junos Configuration Basics — study guide chapter
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FAQ
Junos Configuration Basics — This question tests Junos Configuration Basics — Read the scenario before looking for a memorised answer..
The correct answer is: rollback 0 — Option A is correct because the 'rollback 0' command reverts the candidate configuration to the last committed configuration, discarding all uncommitted changes. In Junos, the rollback command uses a numeric index where 0 always refers to the most recently committed configuration, effectively undoing any uncommitted edits.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Read the scenario before looking for a memorised answer.
About these practice questions
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Same concept, more angles
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. A junior administrator wants to discard all uncommitted changes made in the current configuration session. Which command accomplishes this?
easyWhy B: The `rollback 0` command reverts the candidate configuration to the active committed configuration, effectively discarding all uncommitted changes made during the current session. In Junos, configuration changes are stored in a candidate configuration until explicitly committed; `rollback 0` loads the last committed configuration (index 0) into the candidate, wiping out any uncommitted edits.
Last reviewed: Jun 24, 2026
This JNCIA-JUNOS 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 JNCIA-JUNOS exam.
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