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Hectal
Phase 0Beginner1 of 8 in Networking

How the Internet Actually Works

Packets, layers, and the journey of one request — the mental model every later topic hangs on.

Before subnets, TCP, or Nginx, you need one clear picture: data is chopped into packets, each wrapped in layers of headers, passed hop by hop across networks nobody fully owns, and reassembled at the other end. This phase builds that picture and the vocabulary (latency, bandwidth, layers, encapsulation) you'll use for the rest of the course.

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4 topics ~34 min 7 code blocks & diagrams
Start with the first topic
1
0.1

What a Network Is: Hosts, Links, Packets

A network is devices (hosts) connected by links that exchange small chunks of data called packets; the internet is millions of such networks connected to each other.

12 min 1 diagram 1 code practice

2
0.2

The OSI and TCP/IP Models

Networking is built in layers, each solving one problem and relying on the one below; the OSI model (7 layers) is the teaching vocabulary, the TCP/IP model (4 layers) is what the internet actually runs.

8 min 1 diagram 1 code practice

3
0.3

Encapsulation: Headers All the Way Down

Each layer wraps the data from the layer above in its own header, like envelopes inside envelopes; routers and switches only open the envelopes for their own layer.

7 min 1 diagram 1 code practice

4
0.4

Latency, Bandwidth, Throughput & Jitter

Latency is how long one packet takes, bandwidth is how much the pipe can carry, throughput is how much you actually get; confusing them leads to buying the wrong fix.

7 min 1 code practice