Five ideas that every later chapter leans on — what a network is, the layered model, encapsulation, the three address spaces, and the metrics that decide whether a link feels fast.
5 topics
Networking has a reputation for being a wall of acronyms, and the usual cure — memorize the seven OSI layers, recite the TCP states — is exactly why it never clicks. This chapter takes the other route. It builds the handful of ideas that make the rest of the subject obvious: that the internet moves independent packets rather than reserving circuits, that each layer wraps the one above and trusts the one below, and that three separate address spaces cooperate to get a packet to the right process.
Get these five topics and the later chapters stop being a list of facts to remember and start being consequences of a model you already hold. Skip them and every chapter after this one is rote. The payoff is concrete: by the end you can trace one packet from a browser to a server and name what changes at each hop, and you can say why adding bandwidth does nothing for a slow API.