How to understand that the server does not have enough channel?

Question

System administration

They sell a server with unlimited traffic, but a 100Mbps channel. And further, the more expensive the server, the more, up to 2 Gbps

And how will I understand what exactly this speed is missing? 10,000 users will come to me at the same time, and what will happen? If there is enough memory and CPU. The server won't go down...

Answer 1

will not lie down, but will slump.
determined by network activity monitoring.

Answer 2

Those who have ten thousand users at the same time have specially trained people who deal with such issues.
Or are you just asking theoretically? Then yes - they estimate the peak attendance and select the channel width accordingly.

Answer 3

nload for example. Shows the current load of the network interface, counts the traffic.