Almost every attack travels over a network, so before you can defend one you need to know how data moves across it. This module builds that picture from the ground up, starting with the OSI and TCP/IP models and how each layer wraps the data it carries.
You'll learn how IP addressing, subnetting and routing get a packet from one machine to another, then follow a real request through DNS, the TCP handshake and HTTP/HTTPS. The module finishes with Wireshark, so you can capture traffic and see for yourself what normal looks like, which is the first step to spotting what isn't.
Once you understand how networks work, you'll be ready for the next module, Operating Systems & Linux, where you learn the machines that sit on them.
The seven OSI layers and the four-layer TCP/IP model, how data is encapsulated as it moves down the stack, and why security people think in layers.
How IPv4 and IPv6 addresses work, how subnet masks and CIDR split networks, and how routers and NAT move packets between networks.
The TCP three-way handshake, when UDP is used instead, how DNS resolves a name, and how HTTP and HTTPS carry a request and response. Includes the common ports every analyst should know.
Capturing traffic, using display filters, following a TCP stream, and recognising what a normal DNS lookup or web request looks like on the wire.