The answer is that the 'commit confirmed' command automatically rolls back if not confirmed within the timeout. This is correct because Junos OS uses a two-phase commit model where a confirmed commit activates the candidate configuration for a specified period, typically 10 minutes by default, and if the administrator does not issue a 'commit' command to make it permanent, the system automatically reverts to the previous active configuration. On the JNCIA-Junos exam, this concept tests your understanding of safe configuration practices and the rollback mechanism, often appearing as a trap where candidates confuse 'commit check'—which only validates syntax without activation—with 'commit confirmed'. A common memory tip is to think of the confirmed commit as a "safety net": you jump with a timeout, and if you don't pull the ripcord (confirm), the net (rollback) catches you automatically.
JNCIA-JUNOS Junos OS Fundamentals Practice Question
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.
Which THREE of the following statements are true regarding Junos OS commit operations?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The 'commit check' command validates the candidate configuration without activating it.
Option A is correct because the 'commit check' command validates the candidate configuration for syntax and semantic errors without activating it. This allows an administrator to verify changes before making them active, preventing potential misconfigurations from disrupting network operations.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The 'commit check' command validates the candidate configuration without activating it.
Why this is correct
It checks syntax and semantics without applying.
Related concept
Read the scenario before looking for a memorised answer.
✓
The commit command activates the candidate configuration.
Why this is correct
This is the primary purpose of commit.
Related concept
Read the scenario before looking for a memorised answer.
✓
The 'commit confirmed' command automatically rolls back if not confirmed within the timeout.
Why this is correct
This is the behavior of commit confirmed.
Related concept
Read the scenario before looking for a memorised answer.
✗
You can run multiple commit scripts during a single commit operation.
Why it's wrong here
Only one commit script can be active at a time.
✗
The rollback command reverts to the current active configuration.
Why it's wrong here
Rollback reverts to a previously committed configuration, not the current one.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'rollback' with reverting to the current active configuration, when in fact 'rollback 0' refers to the current active configuration, and any other number refers to a previous committed configuration.
Detailed technical explanation
How to think about this question
The commit operation in Junos OS involves a two-phase process: first, the candidate configuration is validated (which can be done explicitly with 'commit check'), and then it is activated. The 'commit confirmed' command uses a timer (default 10 minutes) to automatically roll back to the previous configuration if not confirmed, which is useful for remote access scenarios where a misconfiguration could lock out the administrator. Under the hood, Junos stores multiple configuration revisions (up to 50 by default) that can be recalled with 'rollback <number>', where 0 represents the current active configuration.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Junos OS Fundamentals — This question tests Junos OS Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The 'commit check' command validates the candidate configuration without activating it. — Option A is correct because the 'commit check' command validates the candidate configuration for syntax and semantic errors without activating it. This allows an administrator to verify changes before making them active, preventing potential misconfigurations from disrupting network operations.
What should I do if I get this JNCIA-JUNOS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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. Which TWO statements correctly describe the function of the 'commit' command in Junos OS? (Choose two.)
easy
✓ A.It validates the candidate configuration for syntax errors.
B.It schedules the configuration to be applied at a later time.
C.It discards the candidate configuration after saving.
✓ D.It saves the candidate configuration to the active configuration.
E.It automatically reboots the device to apply the changes.
Why A: Option A is correct because the 'commit' command in Junos OS first validates the candidate configuration for syntax errors before applying it. If syntax errors are found, the commit fails and the candidate configuration is not applied, ensuring the device does not enter an inconsistent state. This validation step is a core part of Junos's transactional configuration model, where changes are staged in a candidate configuration and then committed atomically.
Variation 2. A Junos device has multiple configuration files saved. Which command shows the available rollback configurations?
medium
A.show system configuration
B.show system rollback
C.show configuration | display rollback
✓ D.show system commit
Why D: Option D is correct because the 'show system commit' command displays a list of all committed configuration revisions, including their commit IDs and timestamps, which are used to roll back to a previous configuration. The rollback feature in Junos relies on these stored commit files, and the command explicitly shows the available rollback points.
Variation 3. A technician is troubleshooting a device that has an inconsistent configuration. They need to revert to the configuration that was committed exactly two commits ago. Which command sequence accomplishes this?
medium
A.rollback 2
✓ B.rollback 2 followed by commit
C.commit confirmed 2
D.rollback 3
Why B: Option B is correct because the `rollback 2` command reverts the candidate configuration to the state it was in two commits ago, but the change is not applied until a `commit` is issued. This two-step sequence (rollback followed by commit) is required to make the reverted configuration active. Without the commit, the device continues running the current active configuration.
Last reviewed: Jun 11, 2026
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.