JN0-106 User Interfaces Practice Question
Tom is a junior network engineer who recently joined a service provider. He is tasked with configuring a new BGP session on an MX240 router to peer with a customer. He accesses the router via SSH and enters configuration mode using the `configure` command. He then navigates to `edit protocols bgp` and begins configuring. He sets the local AS number, adds a group named 'CUSTOMER-A', and specifies the peer IP address 192.0.2.2. After completing the configuration, he attempts to commit by typing `commit`. The system returns a syntax error and indicates that the configuration is invalid. Tom is unsure what went wrong and wants to identify the error before making any changes. What should Tom do next?
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
✓
Issue the `commit check` command to validate the candidate configuration syntax.
The correct action is to issue the `commit check` command (option A), which validates the candidate configuration for syntax and semantic errors without actually committing it, exactly what Tom needs to identify the invalid statement before making changes. On Junos, `commit` itself failed with a syntax error, so running `commit check` will report the specific error location and reason while leaving the active configuration untouched. Option B (`show | compare`) only shows the diff between the candidate and the last committed configuration and does not validate syntax or explain the error. Option C (`run show configuration protocols bgp`) displays the active committed BGP configuration, not the candidate, so it would not reveal Tom's invalid edits. Option D merely re-enters the BGP hierarchy and shows the candidate text but performs no validation, so it would not identify the syntax error.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Issue the `commit check` command to validate the candidate configuration syntax.
Why this is correct
The `commit check` command performs the same full syntax and validation checks as `commit` but without actually activating the candidate configuration. If there is a syntax error, it will immediately report the specific line and the nature of the problem, allowing you to fix it before any impact to the live network. This is the correct first step when a user sees an invalid configuration error.
- ✗
Issue the `show | compare` command to see the differences from the previous committed configuration.
Why it's wrong here
The `show | compare` command displays the differences between the candidate configuration and the currently committed configuration, so it can help you see what changes you've made. However, it does not perform any syntax validation and will not indicate whether a particular line is syntactically invalid or would cause a commit failure. It merely prints the diff in a readable format, so it cannot pinpoint the root cause of a syntax error.
- ✗
Issue the `run show configuration protocols bgp` command to display the current active configuration.
Why it's wrong here
The `run show configuration protocols bgp` command is executed from configuration mode but it retrieves the active committed configuration, not the uncommitted candidate configuration that contains the error. Since the error exists only in the candidate dataset, this command will show the last successfully committed BGP settings and completely miss the problematic line. It provides no visibility into the pending changes that are causing the error.
- ✗
Issue the `edit protocols bgp` command again to re-enter the hierarchy and review the settings.
Why it's wrong here
Re-entering the `edit protocols bgp` hierarchy simply places you back at the same configuration branch; it does not trigger any validation or display the contents of the candidate configuration. While you could then issue a `show` command to view the candidate, the act of re-entering the hierarchy itself does not help identify or diagnose a syntax error. It is a navigation step, not a diagnostic tool.
Go deeper
Related to this question
About these practice questions
One of 326 original JN0-106 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
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.