This 200-901 practice question tests your understanding of cisco platforms and development. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A developer is using a REST API and receives HTTP status codes. Which two codes indicate a client-side error that the developer should fix? (Choose two.)
401 Unauthorized
401 indicates missing or invalid authentication.
500 Internal Server Error
Why wrong: 500 is a server error.
400 Bad Request
400 indicates malformed request.
200 OK
Why wrong: 200 indicates success.
404 Not Found
Why wrong: 404 can be client error but often due to wrong URL; still client error but less direct.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
401 Unauthorized
A 401 Unauthorized status code indicates that the request lacks valid authentication credentials for the target resource. This is a client-side error because the developer must provide correct credentials (e.g., API key, OAuth token) or fix the authentication header in the request. A 400 Bad Request status code means the server cannot process the request due to malformed syntax, invalid request message framing, or deceptive request routing — all issues the developer must correct on the client side.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
401 Unauthorized
Why this is correct
401 indicates missing or invalid authentication.
Related concept
Read the scenario before looking for a memorised answer.
500 Internal Server Error
Why it's wrong here
500 is a server error.
400 Bad Request
Why this is correct
400 indicates malformed request.
Related concept
Read the scenario before looking for a memorised answer.
200 OK
Why it's wrong here
200 indicates success.
404 Not Found
Why it's wrong here
404 can be client error but often due to wrong URL; still client error but less direct.
Common exam traps
Cisco often tests the distinction between client-side (4xx) and server-side (5xx) errors, and the trap here is that 404 Not Found is also a client-side error, but the question asks for two specific codes (401 and 400) that directly indicate the developer must fix the request, not just that the resource is missing.
Detailed technical explanation
Under the hood, HTTP status codes are defined by RFC 7231 (and updated by RFC 7235 for authentication). The 4xx class explicitly indicates that the client (e.g., browser, API consumer) sent an erroneous request. For 401, the server must include a WWW-Authenticate header field (per RFC 7235 Section 3.1) to guide the client on how to authenticate properly. For 400, the server often returns a response body with details about the malformed syntax, such as missing required fields or invalid JSON payload — the developer must parse this to fix the request.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the 200-901 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Cisco Platforms and Development — This question tests Cisco Platforms and Development — Read the scenario before looking for a memorised answer..
The correct answer is: 401 Unauthorized — A 401 Unauthorized status code indicates that the request lacks valid authentication credentials for the target resource. This is a client-side error because the developer must provide correct credentials (e.g., API key, OAuth token) or fix the authentication header in the request. A 400 Bad Request status code means the server cannot process the request due to malformed syntax, invalid request message framing, or deceptive request routing — all issues the developer must correct on the client side.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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