Almost every security test touches a network, so you can't find weaknesses in a system if you don't understand how its data travels. Networking is the language that attackers and defenders share, and fluency in it makes every later module easier.
You'll start with the OSI model, a way of thinking about how data moves through seven layers, then see how TCP sets up a reliable connection with its three-way handshake. From there the module covers IP addressing and subnetting, DNS, the system that turns names into addresses, and finally Wireshark, a tool that lets you capture and read real network traffic yourself.
With the network in your head, you'll be ready for the next module, Linux & Command Line, which looks at the operating system most security tools run on.
A beginner-friendly walk through the seven layers of the OSI reference model and how data moves across a network.
How TCP ensures reliable communication and how a connection is established, in a follow-along lab you can repeat yourself.
The basics of IP addresses, subnetting, and CIDR notation, and how IP ranges are broken down into smaller networks.
Dr Mike Pound explains how the Domain Name System matches website names to IP addresses.
How to capture packets and analyze network traffic with Wireshark, the standard tool for seeing what is really on the wire.