Something I don't understand:
(Tens/hundreds of?) thousands of people simultaneously try to connect to a site like facebook.com or google.com.
From what I understand, they must all necessarily connect to the same initial server (because DNS will return the same IP to many of them, and so all the requests go to the same target destination).
So a single machine/router must handle all the initial requests, even if it plans to forward them to other machines.
How come that single device doesn't get overloaded when this happens?