How to determine if there is Internet or not programmatically?

Question

Delphi

I want to write a program that will visually show whether the Internet is available or not.
And determine the speed is weak or normal. Who will tell you what packet of information should be sent over the Internet and where to determine the speed and connection to the Internet?

Answer 1

InternetGetConnectedState to the rescue.

Answer 2

Start by learning the basic concepts: what is speed, what is connection in IT.
I will say briefly: this is an analysis of network packets (sniffer).