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?