REST API Interview Practice Questions and Answers is my comprehensive toolkit designed to bridge the gap between basic theory and the high-level architectural knowledge required by top-tier tech companies. I’ve built this course to help you navigate the nuances of resource modeling, security protocols like OAuth 2.0, and performance optimization without the fluff. Whether you are a developer preparing for a backend role or an architect refining your design skills, I provide deep-dive explanations for every single option to ensure you understand not just the “what,” but the “why” behind scalable API development. I focus heavily on real-world scenarios, covering everything from idempotency and versioning to the OWASP API Security Top 10, so you can walk into your interview or exam with the confidence of a seasoned professional.
Exam Domains & Sample Topics
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REST Fundamentals & API Design: Constraints, URI structure, and Idempotency.
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Data Handling: Content negotiation, JSON standards, and Serialization.
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API Security: JWT, OAuth 2.0, Rate Limiting, and CORS.
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Optimization: Caching strategies, Pagination, and API Gateways.
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DevOps & Testing: OpenAPI/Swagger, Postman, and Contract Testing.
Sample Practice Questions
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Which of the following HTTP methods is considered both idempotent and safe according to RFC 9110 standards?
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A) POST
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B) PATCH
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C) DELETE
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D) GET
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E) CONNECT
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F) TRACE
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Correct Answer: D & F (Note: In standard MCQ, choose D as the primary answer).
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Overall Explanation: Safety refers to methods that do not modify the resource state, while idempotency means multiple identical requests have the same effect as a single request.
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Option Explanations:
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A) Incorrect: POST is neither safe nor idempotent (it creates resources).
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B) Incorrect: PATCH is not idempotent; repeated applications can change state differently.
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C) Incorrect: DELETE is idempotent but not safe (it modifies state by removing it).
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D) Correct: GET is safe (read-only) and idempotent.
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E) Incorrect: CONNECT is used for tunneling and is not safe.
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F) Correct: TRACE is safe and idempotent as it merely echoes the received request.
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When implementing an OAuth 2.0 flow for a Single Page Application (SPA) with no backend, which grant type is currently recommended by best security practices?
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A) Implicit Grant
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B) Resource Owner Password Credentials
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C) Authorization Code Flow with PKCE
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D) Client Credentials Flow
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E) Refresh Token Flow
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F) Device Code Flow
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Correct Answer: C
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Overall Explanation: Due to security vulnerabilities in the Implicit Flow, the Authorization Code Flow with Proof Key for Code Exchange (PKCE) is now the industry standard for public clients.
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Option Explanations:
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A) Incorrect: Implicit Grant is deprecated due to token leakage risks in the URL.
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B) Incorrect: This requires the user to share their password directly with the app, which is insecure.
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C) Correct: PKCE provides a cryptographically strong mechanism to prevent authorization code interception.
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D) Incorrect: This is for machine-to-machine communication, not user-facing SPAs.
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E) Incorrect: This is used to obtain new access tokens, not for initial authentication.
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F) Incorrect: This is designed for input-constrained devices like Smart TVs.
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If a client requests a resource representation format that the server does not support (e.g., requesting ‘application/xml’ when only ‘application/json’ is available), which HTTP status code should I return?
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A) 400 Bad Request
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B) 403 Forbidden
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C) 404 Not Found
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D) 405 Method Not Allowed
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E) 406 Not Acceptable
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F) 415 Unsupported Media Type
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Correct Answer: E
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Overall Explanation: Content negotiation is handled via the ‘Accept’ header; when the server cannot fulfill this, it triggers a 406 error.
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Option Explanations:
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A) Incorrect: 400 is for generic client-side syntax errors.
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B) Incorrect: 403 is for permission issues.
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C) Incorrect: 404 means the URI itself does not exist.
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D) Incorrect: 405 means the HTTP Verb (like PUT) isn’t allowed on that URI.
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E) Correct: 406 specifically indicates the server cannot produce a response matching the ‘Accept’ headers.
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F) Incorrect: 415 is used when the client sends a payload format (Content-Type) that the server cannot process.
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Welcome to the best practice exams to help you prepare for your REST API Interview Practice Questions and Answers.
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You can retake the exams as many times as you want
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Each question has a detailed explanation
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I hope that by now you’re convinced! And there are a lot more questions inside the course. Enroll today and take the final step toward getting certified!
