How to use this guide

Each chapter follows the same shape, run through the same running example — a single request to https://www.netflix.com:

   The Simple Version (5-year-old)   -> the whole idea, as an analogy
   Deep sections                     -> the real mechanism, with diagrams,
                                         protocol fields, and real config
   Key Takeaways                     -> the handful of facts worth keeping

Read top to bottom the first time — chapters build on each other roughly in the order a request actually happens. After that, treat it as a reference: jump straight to the chapter you need. Every chapter is self-contained enough to read alone if you already know what came before it.

Tools you need: none, strictly. A terminal with curl, dig, and traceroute (all pre-installed on macOS/Linux) lets you reproduce nearly every example yourself, which is worth doing at least once per chapter.