4 lessons
DNS, the internet's phonebook
How typing a name like google.com turns into an actual IP address, through a surprisingly simple chain of questions.
HTTP, and everything that happens when you load a webpage
The request-response conversation your browser has with a server, and exactly which layers from this whole course get used along the way.
FTP, and why file transfer got its own dedicated protocol
Why FTP uses two separate connections at once, and what problem that unusual design was actually built to solve.
Email and the other quiet protocols running the internet
How email actually travels between providers, and a tour of the other application-layer protocols working behind the scenes.