In this video I want to go through what really happens under the hood when you type google.com and you hit enter in a browser. This is inspired by alex’s github page below, it is a great detailed description of what happens. I did however add more details to certain areas and I removed some stuff like keyboard events and low level operating system like that. So if you are interested stay tuned!

https://github.com/alex/what-happens-when

5:30 HSTS https://youtu.be/kYhMnw4aJTw

19:30 tcp vs udp

https://youtu.be/qqRYkcta6IE

24:42 tls

https://youtu.be/AlE5X1NlHgg

40:56 mimesniffing

https://youtu.be/eq6R6dxRuiU

Initial typing

- lookup for most visited sites or an actual search

Google.com Enter

- parse is it a url or search term? If search do a search if url visit website

Which protocol? which port ?

HSTS?

HTTPS

or HTTP?

DNS

cached?

Hosts?

DoH?

Lookup ?

TCP

ip / port ?

arp?

NAT?

proxy?

HTTP 1.1 ? More than one connection

TLS

version? ciphers? Alpn? SNI ? H2 ? H3? Quic?

GET / - ?

Headers compress

cookies?

binary stream?

HTML?

H2 push?

HTML Parse?

Make multiple requests css? JS? Multiple streams?

If H1 then pipeline?