How should a web application be designed to work on a platform where up to...

Use algorithms like random early detection to deny excessive requests.

Set a per-user limit (for example, 5 requests/minute/user) and deny the requests from the users who have reached the limit.

Only 1000 user connections are allowed; further connections are denied so that all connected users can be served.

All requests are saved and processed one by one so that all users can be served eventually.