A DELETE request succeeds, and the client repeats it. The second request returns 404. Does that make DELETE non-idempotent?
Yes, unless the server suppresses the 404 and returns 204 again
No, because idempotency concerns the intended effect on the server, not the response returned✓Richtige Antwort
Yes, because a different status code was returned the second time
No, because 404 is treated as a successful deletion by the spec
Erklärung
Idempotency is defined over the intended effect on the server of repeating the request, and the spec explicitly notes that repeating an idempotent request has the same intended effect even though the response may differ. Nothing requires the second response to match the first.