Which set of HTTP methods are idempotent by design?

Which set of HTTP methods are idempotent by design?

• A. GET, PUT, and DELETE
• B. GET and POST
• C. PUT and PATCH
• D. POST and PATCH

Answer: (A)

This tests the idea of idempotence in HTTP methods—the property that repeating the same request should have the same effect as making it once. GET, PUT, and DELETE are designed so that multiple identical requests don’t produce additional or different changes after the first. GET is idempotent because fetching a resource repeatedly does not alter it. PUT is idempotent because sending the same resource representation repeatedly brings the resource to that exact state, with no extra changes after the first update. DELETE is idempotent because deleting a resource once removes it, and subsequent delete attempts on the now-missing resource do not change the outcome beyond the initial deletion. POST is not idempotent by design, as creating a new resource on each request is a typical behavior. PATCH’s idempotence is not guaranteed and depends on how the patch is defined; repeated patches can lead to different results, so it’s not considered idempotent by design. So the set that is idempotent by design includes GET, PUT, and DELETE.

This tests the idea of idempotence in HTTP methods—the property that repeating the same request should have the same effect as making it once. GET, PUT, and DELETE are designed so that multiple identical requests don’t produce additional or different changes after the first.

GET is idempotent because fetching a resource repeatedly does not alter it. PUT is idempotent because sending the same resource representation repeatedly brings the resource to that exact state, with no extra changes after the first update. DELETE is idempotent because deleting a resource once removes it, and subsequent delete attempts on the now-missing resource do not change the outcome beyond the initial deletion.

POST is not idempotent by design, as creating a new resource on each request is a typical behavior. PATCH’s idempotence is not guaranteed and depends on how the patch is defined; repeated patches can lead to different results, so it’s not considered idempotent by design.

So the set that is idempotent by design includes GET, PUT, and DELETE.