How Computer Networks Actually Work

A request leaves your browser and arrives somewhere across the world in tens of milliseconds. This path follows it the whole way down. You will learn how headers nest as a packet is built, why MTU mismatches cause the classic bug where small requests work and large ones hang, how routers choose a path by longest prefix match and how a BGP mistake can take a network off the internet, how TCP turns an unreliable network into an ordered stream and what congestion control is really negotiating, and why HTTP/3 abandoned TCP for QUIC.