- A
The commit command validates the configuration syntax before applying it.
Syntax validation is performed as part of the commit process.
- B
The commit command automatically saves the configuration to a file on the hard disk.
Why wrong: The configuration is saved in the system's active configuration, not automatically to an external file.
- C
After a commit, the candidate configuration is replaced with the active configuration.
Why wrong: The candidate configuration remains as a copy; it is not replaced.
- D
A commit can include a comment for documentation purposes.
The 'commit comment' command adds a comment to the commit.
- E
A successful commit overwrites the rollback configurations.
Why wrong: Each commit creates a new rollback point without overwriting previous ones.
JNCIA-JUNOS Junos Configuration Basics Practice Question
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.
Which TWO statements are true about the 'commit' operation in Junos?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The commit command validates the configuration syntax before applying it.
Option A is correct because the 'commit' command in Junos performs a full syntax and consistency validation of the candidate configuration before applying it. If any errors are detected, the commit is aborted and the candidate configuration remains unchanged, ensuring the active configuration is never corrupted.
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 command validates the configuration syntax before applying it.
Why this is correct
Syntax validation is performed as part of the commit process.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The commit command automatically saves the configuration to a file on the hard disk.
Why it's wrong here
The configuration is saved in the system's active configuration, not automatically to an external file.
- ✗
After a commit, the candidate configuration is replaced with the active configuration.
Why it's wrong here
The candidate configuration remains as a copy; it is not replaced.
- ✓
A commit can include a comment for documentation purposes.
Why this is correct
The 'commit comment' command adds a comment to the commit.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
A successful commit overwrites the rollback configurations.
Why it's wrong here
Each commit creates a new rollback point without overwriting previous ones.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the 'commit' operation with saving to persistent storage (like Cisco's 'copy running-config startup-config'), but in Junos, 'commit' only activates the configuration in memory and does not automatically write to a file; persistent storage requires an explicit save command.
Detailed technical explanation
How to think about this question
Under the hood, the 'commit' command triggers a two-phase validation: first, a syntax check using the Junos XML API and schema validation, then a semantic check that verifies resource availability and protocol consistency (e.g., BGP peering addresses). If validation passes, the candidate configuration is applied atomically to the active configuration database, and a new rollback snapshot is created. In real-world scenarios, this allows network engineers to safely stage complex changes and roll back to any of the last 50 commits using 'rollback <n>' without losing prior configurations.
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.
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Junos Configuration Basics — study guide chapter
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FAQ
Questions learners often ask
What does this JNCIA-JUNOS question test?
Junos Configuration Basics — This question tests Junos Configuration Basics — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The commit command validates the configuration syntax before applying it. — Option A is correct because the 'commit' command in Junos performs a full syntax and consistency validation of the candidate configuration before applying it. If any errors are detected, the commit is aborted and the candidate configuration remains unchanged, ensuring the active configuration is never corrupted.
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
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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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