What methods are used to determine the distance from the user to the server?

Question

Computer networks

If possible, the name of the technologies

Answer 1

What you need is not the physical distance to the server, but the response time.
Use ping.

Answer 2

What methods are used to determine the distance from the user to the server?

None, it's pointless. Everyone uses RTT .
You can measure the length of the cable from the client to the switch in the entrance, and then - what's the point? Ping, in general, also does not give information "in kilometers" - part of the path data can go through copper, part through optics, plus packet processing delays are non-zero and poorly predictable.

Answer 3

For what purposes do you need.
Geo-distributed data centers use GSLB.