Which statement best describes HTTP POST semantics?

Which statement best describes HTTP POST semantics?

• A. Retrieves a resource without modifying server state.
• B. Creates a new resource and is neither safe nor idempotent, so multiple calls can create duplicates.
• C. Deletes a resource.
• D. Updates a resource with PUT semantics.

Answer: (B)

HTTP POST sends data to the server to create a new resource or trigger an action that changes state. It is not safe because it has side effects on the server, and it is not idempotent because sending the same request multiple times can create duplicates or produce additional effects. This combination—creating a resource and allowing repeated calls to cause more changes—best fits HTTP POST semantics. In contrast, retrieving a resource without changing state describes GET, deleting a resource describes DELETE, and updating a resource with PUT describes PUT, which is typically idempotent and used to replace a resource.

HTTP POST sends data to the server to create a new resource or trigger an action that changes state. It is not safe because it has side effects on the server, and it is not idempotent because sending the same request multiple times can create duplicates or produce additional effects. This combination—creating a resource and allowing repeated calls to cause more changes—best fits HTTP POST semantics. In contrast, retrieving a resource without changing state describes GET, deleting a resource describes DELETE, and updating a resource with PUT describes PUT, which is typically idempotent and used to replace a resource.