What is the idempotency of HTTP methods, and how does it apply to PUT or DELETE?
Answer: Idempotency means multiple identical requests have the same effect as one. PUT → Updating a resource with the same data multiple times results in no further change. DELETE → Deleting a resource repeatedly still results in it being deleted.
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
- Define the concept in one or two sentences.
- Context — where it fits in ASP.NET Web API architecture.
- Example — a specific project, bug, or performance win.
- 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.