12 parts
DNS, TCP, HTTP, TLS, cookies, CORS, caching and CDNs, explained from scratch with steppable diagrams of every handshake and lookup.
The full journey from keystroke to rendered page: DNS, TCP, TLS, HTTP, and rendering. The map this whole networking series fills in, piece by piece.
7 min read
What an IP address actually is, why data travels in packets instead of one stream, and how routers pass them along. The layer under DNS and TCP.
How DNS resolves a domain name to an IP address, step by step: stub resolvers, recursive resolvers, root servers, and why caching makes the second lookup free.
6 min read
How TCP's three-way handshake builds a reliable connection, what UDP skips to go faster, and why video calls and web pages make opposite trade-offs.
The anatomy of an HTTP request and response: methods, headers, bodies, and status codes. Inspect real request/response pairs interactively.
5 min read
The HTTP status codes worth memorizing (200, 201, 204, 400, 401, 404, 409, 500) and the headers that control caching, content, and auth.
How TLS encrypts a connection, why TLS 1.3 needs one round trip instead of two, and what the browser padlock does and doesn't protect.
HTTP/1.1's head-of-line blocking problem, how HTTP/2 fixed it with multiplexing, and why HTTP/3 had to leave TCP behind entirely to fix it again.
HTTP has no memory between requests. Cookies fix that: how Set-Cookie works, session tokens vs stored data, and the flags that keep cookies secure.
Why the browser, not the server, blocks cross-origin requests by default, what a preflight request checks, and how to actually fix a CORS error.
How Cache-Control headers control browser caching, what a CDN actually does, and why cache invalidation is one of the two hard problems in computing.
Use dig, curl -v, and openssl s_client to trace a real HTTPS request through every layer this series covered: DNS, TCP, TLS, and the HTTP exchange.
