Chapter 27 · How Networking Actually Works · Complete Computer Internals

Status: ✅ COMPLETE

Scope: How computers really talk to each other: the network card, MAC and IP addresses, ARP, DNS, DHCP, TCP and UDP, ports and sockets, routing, NAT and firewalls
Time to complete: 120–150 minutes of reading + lab
Prerequisites: Chapter 1 (Complete Computer Architecture), Chapter 4 (Motherboard and Hardware Communication); Chapter 13 (Device Drivers) helps
What you'll know after: What happens, step by step, from plugging in a cable to loading a web page, and how to look at every step on your own Windows PC

INTRODUCTION

Every time you open a web page, send a message or stream a video, a small miracle happens. Your PC finds the right machine among billions, agrees how to talk, sends data in small pieces, and puts it back together in order. It does this in a few milliseconds, and you never see it.

This chapter opens the box. It uses real photos of a network card, a cable, a switch and a router, and a real screenshot of network traffic, so you can see what you are learning about. It uses plain words, and every technical term is explained the first time it appears.

This chapter explains:

The NIC (network card), its MAC address, and the Ethernet frame
The layers of networking and how data is wrapped (encapsulation)
Switches, routers and hubs, and what each really does
IP addresses, IPv4 and IPv6, and subnets
ARP, the trick that turns an IP address into a MAC address
DNS, the Internet's phone book, with caching
DHCP, which gives your PC its address automatically
TCP and UDP, and the three-way handshake
Ports and sockets, which pick the right program
Routing, the default gateway, and NAT in your home router
Firewalls, stateless and stateful

Chapter 28 then shows how Windows itself organises all of this.

CHAPTER OUTLINE

Next chapter: Chapter 28: Windows Networking Internals

Chapter Status: Complete
Estimated reading time: 130 minutes
Practical time: 35 minutes
Knowledge check time: 30 minutes