JN0-106 Junos Configuration Basics Practice Question
Which TWO statements about the 'commit' operation in Junos are correct?
⚠ Common exam trap
Candidates often confuse the standard 'commit' with 'commit confirmed', which includes a 10-minute rollback timer, and assuming that Junos allows partial commits like some other platforms (e.g., Cisco's 'commit' with 'only' option).
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 operation validates syntax before applying, and if errors are found, the commit fails.
Option A is correct because when you run commit, Junos first performs a syntax check on the candidate configuration, and if any syntax errors are detected, the commit fails and the candidate configuration is not activated. Option E is correct because the commit operation merges the candidate configuration into the active configuration, making it the new running (active) configuration on the device. Option B is incorrect because automatic rollback after 10 minutes only occurs with the 'commit confirmed' command, not a standard commit. Option C is incorrect because Junos commits the entire candidate configuration; partial commits are not supported (you would use configuration groups or 'commit check' for validation instead). Option D is incorrect because commit applies changes immediately, not at the next system reboot.
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 operation validates syntax before applying, and if errors are found, the commit fails.
Why this is correct
The commit operation first checks the candidate configuration for syntactic and schema errors using the Junos configuration validation engine. If an error is found — such as an invalid IP prefix, a missing mandatory statement, or an unknown hierarchy — the commit aborts and the candidate configuration remains unchanged. No part of the configuration is applied until the entire candidate passes validation, ensuring that only well-formed configurations become active.
- ✗
The commit operation automatically rolls back changes after 10 minutes if not confirmed.
Why it's wrong here
This behavior describes the 'commit confirmed' feature, not a standard commit. A normal commit makes changes permanent immediately, with no timer, while 'commit confirmed' installs a temporary configuration and automatically reverts to the previous one after a configurable interval (default 10 minutes) if the operator does not issue a confirming commit. The standard commit command never schedules an automatic rollback; you must explicitly use 'rollback' to revert changes.
- ✗
The commit operation allows you to commit only a specific portion of the configuration.
Why it's wrong here
A standard commit operation always commits the entire candidate configuration, regardless of which portions were edited or how many changes were made. While Junos offers a 'commit partial' command for use in specific workflows, that command has limitations and is not what is normally called 'the commit operation.' The ordinary commit atomically activates every change in the candidate configuration, not a selected subset.
- ✗
The commit operation applies the configuration changes at the next system reboot.
Why it's wrong here
Junos applies the configuration to the running system immediately at commit time. The active configuration is updated in place, and the new settings take effect on the running processes and interfaces right away. There is no dependency on a reboot; in fact, Junos is designed to accept configuration changes while the device is live, and rebooting only re-reads the active configuration, it does not delay or trigger the application of the commit.
- ✓
The commit operation activates the candidate configuration as the new active configuration.
Why this is correct
The commit operation is the mechanism by which the candidate configuration — a separate, editable copy — is copied over and becomes the active configuration. Once committed, this configuration is used by the system and is the configuration that would be loaded on the next reboot. It is the single step that makes your changes permanent and operational.
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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.