hardMultiple ChoiceObjective-mapped
200-901 Practice Question: An engineer needs to troubleshoot a RESTCONF…
An engineer needs to troubleshoot a RESTCONF request that returns a 409 Conflict error when trying to modify a YANG data node. What is the most likely cause?
⚠ Common exam trap
Cisco often tests the distinction between HTTP status codes in RESTCONF, and the trap here is that candidates confuse a 409 Conflict with a generic 'modification failure' and incorrectly attribute it to permissions (401) or model issues (400/404), rather than recognizing it as a concurrency control mechanism.
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 resource was modified by another client during the operation
A 409 Conflict error in RESTCONF specifically indicates a resource state conflict, typically caused by a YANG data store version mismatch detected via the 'if-match' header or ETag validation. When another client modifies the same resource between the time a client retrieves it and attempts to update it, the server rejects the request to prevent lost updates, enforcing optimistic locking as defined in RFC 8040.
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 data node is read-only
Why it's wrong here
Read-only would return a 405 Method Not Allowed or 403.
- ✗
Authentication failure
Why it's wrong here
Authentication failure returns 401 Unauthorized.
- ✓
The resource was modified by another client during the operation
Why this is correct
409 Conflict indicates a conflict with the current state.
- ✗
The YANG model version mismatch
Why it's wrong here
Model mismatch would typically yield a 400 Bad Request.
Go deeper
Related to this question
About these practice questions
This 200-901 question is part of Courseiva's 989-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 practice question is part of Courseiva's free Cisco 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 200-901 exam.