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How networks work

Seven lessons on how data gets from one device to another: packets, the layers, Ethernet and switches, Wi-Fi, IP and routers, TCP and UDP, and everything that happens when a web page loads. No programming needed.

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How it works

Each lesson is a short read with examples, then a few practice questions. Some ask you to type an answer (a number, an address, what a piece of code prints), some have you pick one, and some have you tap steps or lines into the right order. You can try again as often as you like; after two misses there’s a button to show the answer.

What do I need to know first?

Nothing. It starts from zero. The how computers work course helps with binary, but you don't need it.

The other networking courses

Where is my progress saved? In this browser, like the rest of the site. Nothing to sign up for.