Why Did commit check Fail? Diagnosing Errors
Exhibit
user@router# commit check error: configuration check-out failed: syntax error '1.1.1.1/32' error: policy-options policy-statement test term 0 from protocol is not valid
Refer to the exhibit. What is the most likely cause of the error?
Quick Answer
The answer is a syntax error in the policy-statement 'test' within the protocol match condition. This is correct because the commit check failure message explicitly identifies a syntax issue when Junos attempts to validate the protocol match; the system only accepts predefined protocol names like 'bgp', 'ospf', or 'static', so any misspelling or invalid entry triggers an immediate rejection during the commit check. On the JNCIA-Junos exam, this scenario tests your understanding of policy-options syntax validation and the commit check process, which is a common trap where candidates overlook exact protocol naming. A reliable memory tip is to think of the protocol match as a strict dropdown list—Junos does not guess or autocorrect, so always verify the spelling against the official protocol names in the configuration guide.
⚠ Common exam trap
The trap here is that candidates may misinterpret a syntax error as a warning or an IP conflict, because Junos error messages can be verbose, but the key is to identify the specific line number and the 'syntax error' keyword in the output, which points directly to a configuration mistake in the policy-statement.
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 policy-statement 'test' contains a syntax error in the protocol match condition.
The error message in the exhibit indicates a syntax error in the policy-statement 'test' when using the protocol match condition. In Junos, the 'protocol' match condition requires a valid protocol name (e.g., 'bgp', 'ospf', 'static'), and if an invalid or misspelled protocol is specified, the commit check fails with a syntax error. This is a common mistake when configuring policy-options, as the Junos CLI validates the protocol against a predefined list.
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 IP address 1.1.1.1/32 is already in use.
Why it's wrong here
The error is about the policy-statement, not the IP address being in use.
- ✗
The candidate configuration has no errors and this is a warning.
Why it's wrong here
It is an error, not a warning, and the commit check failed.
- ✓
The policy-statement 'test' contains a syntax error in the protocol match condition.
Why this is correct
The error indicates 'protocol is not valid' in the policy-statement.
- ✗
The commit check command requires user confirmation.
Why it's wrong here
Commit check runs and reports errors without requiring confirmation.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
About these practice questions
Courseiva writes every JN0-106 question from scratch — 156 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 →
Same concept, more angles
1 more way this is tested on JN0-106
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Refer to the exhibit. What is the most likely cause of the commit check failure?
medium- A.The routing instance has not been created.
- B.The interface xe-0/0/0 has been disabled using the 'disable' statement.
- C.The IP address is a duplicate on the subnet.
- ✓ D.The 'family inet' statement is missing under unit 0.
Why D: In Junos, the 'disable' statement is used to administratively disable an interface. This is a valid configuration and does not cause a commit check failure. The commit check would succeed, and the interface would simply be operationally down. A common cause of commit check failure is referencing an interface in a routing instance without the required protocol family configured, such as missing 'family inet' under unit 0. This generates a commit error because the routing instance expects the interface to support the address family.
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.