Life of a Packet
So far, we have covered all the basics of how web applications deliver data to an end-user through a network. Starting from the initiation of a TCP connection on the transport layer, all the way to the resolution of IP addresses through DNS servers; we have outlined the communication process between clients and servers. To make things clearer, we will now look at exactly how any given data packet travels through the web to reach its destination.
This video gives a nice introduction to how packets travel through the Internet. This video is a bit dated, and some terminology used in it might not exactly be up-to-date, but the underpinnings are essentially the same today. It is a nice overview for beginners.