JN0-106 Junos Configuration Basics Practice Question
An engineer has modified the configuration and wants to apply changes but also wants to verify that the changes are syntactically correct before committing. What command should the engineer use?
⚠ Common exam trap
Many candidates confuse `commit check` with `commit confirmed`, thinking both validate syntax, but `commit confirmed` actually commits the configuration and relies on a rollback timer, not a pre-commit syntax check.
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
✓
commit check
The `commit check` command validates the candidate configuration for syntax errors without activating it. This allows the engineer to verify that the changes are syntactically correct before committing, ensuring the configuration is valid and reducing the risk of committing a broken configuration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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rollback
Why it's wrong here
The 'rollback' command in Junos does not apply a candidate configuration; instead it discards uncommitted changes and reverts the candidate configuration to the last committed configuration, or to a specific rollback point (e.g., 'rollback 1'). Since the engineer wants to apply the modified configuration, issuing rollback would delete those edits and restore the previous active configuration, leaving the device unchanged from its current operational state. This makes it the opposite of what is needed to bring the new configuration into effect.
- ✗
commit confirmed
Why it's wrong here
The 'commit confirmed' command applies the configuration temporarily, but it requires a confirmation timeout (default 10 minutes) and automatically reverts to the previous configuration if the engineer does not issue a confirming 'commit' within that interval. While it does apply the configuration, it is designed for safe remote changes where the engineer might lose connectivity; it is not a validation-only step. In this scenario, the engineer has already modified the configuration and simply wants to apply it, so a confirmed commit would leave the device in a pending state rather than permanently and immediately applying the changes.
- ✓
commit check
Why this is correct
The 'commit check' command validates the syntax, semantics, and consistency of the candidate configuration against the Junos schema without activating it. It reports errors such as invalid statements, missing mandatory parameters, or referencing non-existent interfaces, but it never modifies the running configuration. Because the engineer wants to apply the modified configuration, commit check is the correct first step to ensure the changes are valid before performing an actual commit, but note that it does not itself apply the configuration—it only verifies it.
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commit
Why it's wrong here
The 'commit' command immediately activates the candidate configuration, making it the active running configuration and the new rollback baseline. This is the actual command that applies changes; however, unlike 'commit check', it does not pre-validate the configuration beyond basic syntax checks, so if there are semantic errors or missing dependencies, the commit may fail or, in some cases, render services temporarily disrupted. In the context of the question, the engineer wants to apply the configuration, so commit does accomplish that, but it lacks the verification step that commit check provides before activating changes.
About these practice questions
Courseiva writes every JN0-106 question from scratch — 326 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This JN0-106 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 JN0-106 exam.