Returning appropriate HTTP status codes?

Short answer: Use proper status codes: 200 OK (success) 201 Created (on POST) 204 No Content (on DELETE) 400 Bad Request 401 Unauthorized / 403 Forbidden 404 Not Found 500 Internal Server Error return Ok(result);

Example code

return NotFound();
return BadRequest(ModelState);

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.