This JNCIA-JUNOS practice question tests your understanding of junos os fundamentals. 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.
Refer to the exhibit. user@router> show system commit 0 2025-03-20 10:15:23 UTC by admin via cli 1 2025-03-20 09:45:10 UTC by root via cli (confirmed) 2 2025-03-19 14:30:00 UTC by admin via cli
Refer to the exhibit. The network administrator made a change that caused connectivity loss. They need to revert to the configuration before the most recent commit. Which command would accomplish this?
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.
Refer to the exhibit. user@router> show system commit 0 2025-03-20 10:15:23 UTC by admin via cli 1 2025-03-20 09:45:10 UTC by root via cli (confirmed) 2 2025-03-19 14:30:00 UTC by admin via cli
rollback 0
C reverts to config before last commit.
rollback 3
Why wrong: D is not a valid rollback point.
rollback 2
Why wrong: B would go back three commits.
rollback 1
Why wrong: A would go back two commits, not one.
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
The correct answer is A, rollback 0. In Junos, the rollback command reverts the active configuration to a previously committed configuration file. The most recent commit is stored as rollback 0, so issuing 'rollback 0' restores the configuration that was active before the last commit, effectively undoing the change that caused connectivity loss.
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
C reverts to config before last commit.
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.
rollback 3
Why it's wrong here
D is not a valid rollback point.
rollback 2
Why it's wrong here
B would go back three commits.
rollback 1
Why it's wrong here
A would go back two commits, not one.
Common exam traps
The trap here is that candidates often confuse rollback 0 with the current active configuration, when in fact rollback 0 is the most recent commit, and rollback 1 is the configuration before that commit, so to revert the last change you need rollback 0, not rollback 1.
Detailed technical explanation
Junos maintains up to 50 previous committed configurations (rollback 0 through rollback 49) in the /config directory. Rollback 0 always points to the most recently committed configuration, while rollback 1 points to the configuration before that. When you issue 'rollback 0', you are loading the configuration that was active before the last commit, which is exactly what is needed to revert a change. This is different from Cisco IOS, where the 'reload' command is used to revert to a saved startup configuration.
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
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FAQ
Junos OS Fundamentals — This question tests Junos OS Fundamentals — Read the scenario before looking for a memorised answer..
The correct answer is: rollback 0 — The correct answer is A, rollback 0. In Junos, the rollback command reverts the active configuration to a previously committed configuration file. The most recent commit is stored as rollback 0, so issuing 'rollback 0' restores the configuration that was active before the last commit, effectively undoing the change that caused connectivity loss.
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.
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Last reviewed: Jun 24, 2026
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