hardMultiple Choice
200-901 Practice Question: A developer is troubleshooting an API call to…
A developer is troubleshooting an API call to Cisco SD-WAN vManage. The request fails with HTTP 400 status and the response body: '{"error": "Bad Request", "details": "Invalid JSON: unexpected token at position 42"}'. Which tool or technique should the developer use to quickly identify the syntax error?
⚠ Common exam trap
Cisco often tests the ability to map specific HTTP status codes and error messages to the correct troubleshooting tool, and the trap here is that candidates may confuse a JSON syntax error (400) with an authentication error (401/403) or a missing-field error (422), leading them to choose options like checking the API key or reviewing documentation instead of using a JSON validator.
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
✓
Use a JSON validator to check the request body.
The HTTP 400 status code indicates a client-side error, and the response body explicitly states 'Invalid JSON: unexpected token at position 42'. This means the request body contains malformed JSON. A JSON validator (e.g., jsonlint.com, jq, or a library like `json.loads()` in Python) will parse the JSON and pinpoint the exact syntax error (e.g., a missing comma, extra brace, or unescaped quote) at the specified position, allowing the developer to fix the request body quickly.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use a JSON validator to check the request body.
Why this is correct
The response pinpoints a malformed JSON token at position 42, so the request body itself is invalid. A JSON validator parses the payload and reports the exact syntax fault, letting the developer correct it before resending the vManage call.
- ✗
Increase the timeout value for the HTTP request.
Why it's wrong here
Timeout values govern how long the client waits for a response; the server replied promptly with HTTP 400 and a JSON parse error, so latency plays no part. Raising timeouts is tempting when requests fail intermittently, but that scenario manifests as connection or read timeouts, not a syntax error at a character position.
- ✗
Check the API key validity in the header.
Why it's wrong here
An invalid or missing API key produces HTTP 401 or 403, not 400, and the response body already pinpoints a JSON syntax fault at position 42. Checking credentials is tempting because authentication failures are frequent causes of failed API calls, but that scenario would not return a parser token error.
- ✗
Review the API documentation for required fields.
Why it's wrong here
Documentation lists required fields, but the error explicitly reports invalid JSON syntax at position 42, so field presence is irrelevant. It is tempting because missing or malformed fields commonly cause HTTP 400 responses; however, that scenario returns schema-validation messages, not a parser token error naming a character offset.
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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.