Learning track

Internet and networks

Most problems reported as "the internet is broken" have happened in one of four or five specific links, and each link has its own owner and its own tools. This path opens those links one at a time, in an order where each lesson helps you locate the next fault.

  • 12 lessons
  • Free, no signup

Four links, in the order you learn them

  1. 1 The journey of a request

    The first two lessons: how the internet works and what a network is. Without them the rest is names with no meaning.

  2. 2 Addresses

    IP, DNS and the structure of a URL. Most faults that look like an outage have happened here.

  3. 3 Protocols and machines

    HTTP and HTTPS, servers, content delivery networks and email. Where the work of a website meets the work of a network.

  4. 4 Your own network

    Wifi and the modem, bandwidth and speed, and cookies. The only link that is entirely in your hands.

These four links are a learning order, not a formal network layering. The formal models have seven or four layers and are needed for engineering work, but for locating a fault these four are enough.

The path, step by step

Lessons are ordered so each stands on the previous one. You can also jump in anywhere.

  1. 1How the internet actually worksThe internet is not one big network. It is a network of networks, each piece separately owned, all of them agreeing on one shared language. Whatever you open travels from your device to a server as small numbered packets, station by station, and the answer comes back the same way.Beginner
  2. 2What a network is, and the types of networkA network is two or more devices that have a way to exchange data and each have their own address; that is all. Home wifi, a company network and the internet itself are three sizes of that one idea, and what separates them is scale and who owns each piece.Beginner
  3. 3What an IP address isAn IP address is where a device sits on a network, the place packets have to reach, and every packet leaving your device carries a destination address and a return address on it. The address says where to deliver; it does not say who is sitting behind the device.Beginner
  4. 4What DNS isDNS is the address book of the internet: it takes a domain name like rgb.ir and returns the numeric address of the server the browser has to connect to. What an ordinary address book does not do is cache the answer at every point along the way, and that caching is the main reason a record change is not instant.Beginner
  5. 5The anatomy of a web address (URL)A web address is not a string of letters but five parts with different jobs: the protocol, the domain, the path, the query and the anchor. The only part to look at when you are judging whether a link is fake is the domain, and every other part can be anything at all.Beginner
  6. 6What HTTP and HTTPS areHTTP is the agreement a browser and a server talk in: the browser sends a request, the server returns a response, and a three digit code says whether it worked. HTTPS is that same agreement travelling inside an encrypted layer, so nobody in the middle can read the content or change it.Beginner
  7. 7What a server is, and the types of serverA server is a computer whose job is to answer other people requests, which is why it stays on all the time; its hardware is not a different kind of thing from your computer, its duty is. What we call a website server is really several layers stacked: hardware, an operating system, a web server, and the program that builds the page.Beginner
A glass globe with five glowing rings of connection in red, green, blue and white

The order of these lessons starts with the journey of a request rather than with definitions, because a definition without a route is forgotten. First you see where your packet passes through, then we go to addresses, meaning IP, DNS and the structure of a URL, then to protocols and machines, and finally to the things in your own home that are in your hands.

This path is the layer the other two stand on. Someone studying web design finds half the error messages meaningless without understanding domains and servers; and security in practice is this same network, plus knowing what you must not leave open. So if you are just starting, beginning here saves time rather than costing it.

One honest warning is needed too: none of these lessons makes you a network engineer. The goal is lower and more useful than that: being able to say where the problem is, who you need to talk to, and which piece of advice you read on the internet must not be applied.

Real follow-up questions

Do I need to know programming to learn about networks?

No. What is needed is the patience to run a few simple commands and read their output. Every lesson in this path uses tools that already exist on any Windows, Mac or Linux machine and need nothing installed.

Is this path useful for someone who runs a website?

Yes, and more than it looks. A site owner needs to be able to tell whether a problem comes from the hosting, the domain or their own connection, because until they can, they take every issue to the wrong person. The DNS, server and CDN lessons exist for exactly that.

Do I need a networking certificate to get work?

For professional network jobs inside organisations a certificate still appears in the hiring requirements, and this path does not replace those courses. But for someone who runs a website or works in a digital team, what counts is capability rather than paper: being able to read an output and make the right call.

This path is written for someone who wants to understand what is going on underneath their own site. If you would rather hand that layer to someone who keeps servers themselves, see the hosting page