HTTP — end of module

What this checks. That you can separate what HTTP says from what carries it, and place the versions correctly. You need 3 of 4 to pass, and every option is explained afterwards — including the ones you did not pick.

1. 1/4Why does an HTTP/1.1 request carry a Host header when IP already has the address?

   Match a field to its purpose

   So one address can serve many sites — the server needs to know which one you meant

   So the server can verify the DNS answer

   For logging only
2. 2/4Which statement about HTTP versions is accurate?

   Tell two ideas apart

   HTTP/1.1 and HTTP/2 run over TCP; HTTP/3 runs over QUIC, which runs over UDP

   All HTTP versions run over TCP

   HTTP/2 replaced text with binary and also replaced TCP
3. 3/4DNS resolves, the handshake completes, the request is delivered and acknowledged, and a complete response comes back reading 500 Internal Server Error. Which layer failed?

   Diagnose a failure

   None of the network layers — the server application failed and said so

   TCP, because the response was an error

   DNS, because it may have returned the wrong server
4. 4/4A client sends a request with `Connection: close` on HTTP/1.1. After the response is fully received, what happens?

   Predict what happens next

   The connection is closed — a further request needs a new one

   The connection stays open for reuse, because 1.1 always does

   The server sends a RST immediately