Quick Answer
The answer is the `rollback 1` command. This is correct because in Junos, the rollback command uses a numeric index where `0` represents the current active configuration, `1` refers to the most recently committed configuration, and higher numbers reach further back into the commit history. When a router behaves unexpectedly after a change, `rollback 1` instantly reverts the active configuration to the previous commit, undoing the unwanted modification without manual editing. On the JNCIA-Junos exam, this concept tests your understanding of Junos configuration management and the commit model, often appearing as a straightforward command-choice question. A common trap is confusing `rollback 0` (which does nothing) with `rollback 1`—remember that `1` is the undo button for the last commit. For a quick memory tip, think of the number `1` as meaning “one step back” to the previous working state.
This JNCIA-JUNOS practice question tests your understanding of operational monitoring and maintenance. 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.
After a configuration change, a router is not behaving as expected. The administrator wants to rollback to the previous configuration. Which command accomplishes 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.
rollback 0
Why wrong: Remains on the current configuration.
commit check
Why wrong: Validates the configuration but does not revert.
rollback 1
Reverts to the previous committed configuration.
load override current
Why wrong: Loads a configuration file, not a rollback.
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 1
Option C is correct because the 'rollback 1' command reverts the active configuration to the most recent committed configuration (the one before the latest commit). In JUNOS, the rollback command uses a numeric index where 0 is the current active configuration, 1 is the previous committed configuration, and higher numbers go further back. This allows the administrator to undo an unwanted configuration change without manually editing the configuration.
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 it's wrong here
Remains on the current configuration.
commit check
Why it's wrong here
Validates the configuration but does not revert.
rollback 1
Why this is correct
Reverts to the previous committed configuration.
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.
load override current
Why it's wrong here
Loads a configuration file, not a rollback.
Common exam traps
The trap here is that candidates familiar with Cisco IOS might think 'rollback 0' undoes the last change, but in JUNOS, rollback 0 refers to the current active configuration, not the previous one.
Detailed technical explanation
JUNOS maintains a history of up to 50 previous committed configurations, accessible via 'rollback <n>' where n ranges from 0 (current) to 49 (oldest). The rollback command copies the specified configuration into the candidate configuration, which must then be committed to take effect. This is different from Cisco IOS, where 'rollback' is used in the context of configuration replace or archive; JUNOS rollback is a straightforward way to revert to a known good state without needing a separate backup file.
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.
Operational Monitoring and Maintenance — study guide chapter
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Operational Monitoring and Maintenance practice questions
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FAQ
Operational Monitoring and Maintenance — This question tests Operational Monitoring and Maintenance — Read the scenario before looking for a memorised answer..
The correct answer is: rollback 1 — Option C is correct because the 'rollback 1' command reverts the active configuration to the most recent committed configuration (the one before the latest commit). In JUNOS, the rollback command uses a numeric index where 0 is the current active configuration, 1 is the previous committed configuration, and higher numbers go further back. This allows the administrator to undo an unwanted configuration change without manually editing the configuration.
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
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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