JN0-106 Junos Configuration Basics Practice Question
In a dual Routing Engine (RE) setup, an engineer commits a configuration change that should be applied to both REs synchronously. What is the correct command to ensure both REs receive the same configuration immediately?
⚠ Common exam trap
A common mix-up: candidates confuse 'commit synchronize' with 'commit check' or 'commit confirmed', not realizing that only 'commit synchronize' explicitly pushes the configuration to the backup RE in a dual-RE setup.
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 synchronize
The 'commit synchronize' command commits the configuration on the master Routing Engine and then automatically copies and commits the same configuration to the backup RE, ensuring both REs have identical active configurations immediately. This is the standard Junos method for synchronizing configurations in a dual-RE chassis.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
commit confirmed
Why it's wrong here
This command activates the candidate configuration on the local Routing Engine with a built-in automatic rollback timer. It does not propagate the configuration to the other RE, so the standby continues running the old configuration, creating a split configuration state. If you need synchronized commit with automatic rollback, you'd have to combine it with the synchronize option, which is not what plain 'commit confirmed' does.
- ✗
commit check synchronize
Why it's wrong here
This performs a syntactic and semantic validation of the candidate configuration on both Routing Engines without making any changes active. It is analogous to a dry-run, ensuring the configuration is error-free before an actual commit. Since it does not apply the configuration, it cannot be used to implement a change across both REs.
- ✗
commit and-quit
Why it's wrong here
This commits the configuration on the current Routing Engine and immediately leaves configuration mode. However, it lacks the 'synchronize' keyword, meaning the other Routing Engine is unaffected and retains its prior configuration. This can lead to a mismatch if the device fails over or if operational commands are run on the standby RE.
- ✓
commit synchronize
Why this is correct
This commits the candidate configuration to both Routing Engines in a single atomic operation, ensuring both have identical active configurations. It is the standard command for applying changes in a dual-RE chassis, and it is essential for maintaining consistency and enabling clean failover. The commit is performed on the local RE and the other RE simultaneously.
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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.