Interview Q&A

• Rate limiting restricts the number of API requests per user/IP in a given time.
• Prevents abuse (DDoS, brute force).
• Ensures fair usage and protects backend systems.
• Return 429 Too Many Requests with Retry-After header.

👉 Example: 100 requests/minute per API key.

• Ensures correctness, reliability, performance, and security of APIs.
• Postman → Manual and automated API testing, environment variables, collections.
• Swagger (OpenAPI) → Live documentation, mock servers, auto-generated client

SDKs.

• Automates QA process and reduces bugs in production.

Caching is storing frequently used data temporarily to reduce server load and improve

response time.

Implementation methods:

• HTTP caching headers (Cache-Control, ETag, Expires).
• Reverse proxies (Varnish, NGINX).
• In-memory stores (Redis, Memcached).
• Client-side caching using 304 Not Modified.

• Content negotiation allows clients to specify desired response format.
• Uses HTTP headers:
• Accept: application/json → Request JSON.
• Accept: application/xml → Request XML.
• The server returns response in requested format (if supported).

👉 Example in ASP.NET Core: Add XML formatter with

services.AddControllers()

.AddXmlSerializerFormatters();

PI performance?

• A CDN caches and delivers static or semi-static content from edge servers close to

users.

• Reduces latency and improves response times.
• Helps with traffic offloading, reducing load on origin servers.
• Supports DDoS protection and scaling under heavy loads.

👉 Example: Cloudflare, Akamai, AWS CloudFront.

• A CDN caches and delivers static or semi-static content from edge servers close to

users.

• Reduces latency and improves response times.
• Helps with traffic offloading, reducing load on origin servers.
• Supports DDoS protection and scaling under heavy loads.

👉 Example: Cloudflare, Akamai, AWS CloudFront.

🔹 API Documentation & Tools – Interview Q&A

• Swagger/OpenAPI is a specification for defining REST APIs.
• Provides machine-readable and human-readable documentation.
• Enables automatic client SDK generation, testing, and validation.
• Improves team collaboration and consistency in API design.

Answer: Contains all endpoints, request/response formats, parameters, headers, and security details. Acts as a contract between client and server. Used for auto-generating documentation, client SDKs, and mock servers.

What interviewers expect

• A clear definition tied to REST API in ASP.NET Web API projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Web API application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Web API architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

• RAML (RESTful API Modeling Language) → YAML-based specification for APIs.
• Focuses on design-first API approach.
• Differences with OpenAPI/Swagger:
• RAML is more design-oriented; Swagger is implementation-oriented.
• OpenAPI has better tooling support and community adoption.

Answer: Postman is a GUI tool for testing REST APIs. Features: Send HTTP requests (GET, POST, PUT, DELETE). Automate tests using Postman Collections. Generate documentation and mock servers. Supports environment variables and CI/CD integration.

What interviewers expect

• A clear definition tied to REST API in ASP.NET Web API projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Web API application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Web API architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Answer: PIs? Return a structured JSON response with: status → HTTP status code error → Short message details → Optional for debugging Example: { "status": 400, "error": "Bad Request", "details": "Email is required" }

What interviewers expect

• A clear definition tied to REST API in ASP.NET Web API projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Web API application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Web API architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.