hardMultiple ChoiceObjective-mapped
200-901 Practice Question: Refer to the exhibit
Exhibit
HTTP/1.1 400 Bad Request
Content-Type: application/yang-data+json
{
"ietf-restconf:errors": {
"error": [
{
"error-tag": "malformed-message",
"error-message": "Invalid JSON syntax at line 3, column 12"
}
]
}
}Refer to the exhibit. A developer receives this response when attempting to send a PATCH request to modify a YANG data node via RESTCONF. What is the most likely cause?
⚠ Common exam trap
Cisco often tests the distinction between HTTP status codes for RESTCONF errors, and the trap here is that candidates confuse a 400 Bad Request (payload issue) with a 404 Not Found (resource missing) or a 401 Unauthorized (auth issue), especially when the question describes a 'modify' operation that might imply the resource exists.
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 JSON payload is malformed
A PATCH request to modify a YANG data node via RESTCONF returns a 400 Bad Request status when the JSON payload is malformed. RESTCONF (RFC 8040) requires the request body to conform to the YANG module's data model; if the JSON syntax is invalid or the data does not match the schema (e.g., missing required fields, incorrect data types), the server rejects the request with a 400 error. The 400 status code specifically indicates a client-side error in the request payload, not an authentication or resource existence issue.
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 resource does not exist
Why it's wrong here
Non-existent resource would return 404.
- ✗
The authentication token is expired
Why it's wrong here
Expired token returns 401.
- ✗
The YANG model is not supported
Why it's wrong here
Unsupported model would return a different error.
- ✓
The JSON payload is malformed
Why this is correct
The error-tag 'malformed-message' indicates JSON syntax error.
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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.