Quick Answer
The answer is rollback 2. In Junos OS, the rollback number directly corresponds to how many commits ago a configuration was saved, with rollback 0 being the most recent commit, rollback 1 the one before that, and so on. To revert to the configuration committed two commits ago, you must specify rollback 2, because the number counts backward from the current active configuration. On the JNCIA-Junos exam, this concept tests your understanding of Junos configuration management and the rollback feature, often appearing in questions about reverting changes after a failed commit. A common trap is confusing the rollback number with the number of changes or thinking rollback 1 refers to the first saved configuration, but remember: the number is the count of commits to undo. A helpful memory tip is to think of the rollback number as the “steps back” from where you stand now—rollback 0 is your current step, so two steps back is rollback 2.
This JNCIA-JUNOS practice question tests your understanding of user interfaces. 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 network engineer needs to revert to the configuration that was committed two commits ago. Which rollback number should they use?
rollback 0
Why wrong: rollback 0 reverts to the current active configuration.
rollback 2
rollback 2 reverts to the configuration committed two commits ago.
rollback 1
Why wrong: rollback 1 reverts to the immediately previous commit.
rollback 3
Why wrong: rollback 3 would go back three commits.
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 2
The rollback command in Junos OS allows reverting to a previously committed configuration. The rollback number corresponds to the number of commits ago, starting with rollback 0 for the most recent commit, rollback 1 for the commit before that, and so on. Therefore, to revert to the configuration committed two commits ago, the correct rollback number is 2.
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
rollback 0 reverts to the current active configuration.
rollback 2
Why this is correct
rollback 2 reverts to the configuration committed two commits ago.
Related concept
Read the scenario before looking for a memorised answer.
rollback 1
Why it's wrong here
rollback 1 reverts to the immediately previous commit.
rollback 3
Why it's wrong here
rollback 3 would go back three commits.
Common exam traps
The trap here is confusing the rollback number with the number of commits to revert, where candidates might mistakenly think rollback 1 means one commit ago (which is correct) but then incorrectly apply that logic to two commits ago by choosing rollback 1 instead of rollback 2.
Detailed technical explanation
Junos OS maintains up to 50 previous committed configurations in the /config directory, named juniper.conf.gz through juniper.conf.49.gz. The rollback command loads the specified configuration into the candidate configuration without automatically committing it, allowing the engineer to review and then commit if desired. This feature is critical for quickly recovering from configuration errors without needing external backups.
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
User Interfaces — This question tests User Interfaces — Read the scenario before looking for a memorised answer..
The correct answer is: rollback 2 — The rollback command in Junos OS allows reverting to a previously committed configuration. The rollback number corresponds to the number of commits ago, starting with rollback 0 for the most recent commit, rollback 1 for the commit before that, and so on. Therefore, to revert to the configuration committed two commits ago, the correct rollback number is 2.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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