Pieces of your Home Network Part 1 – “What is a network?”

In this series of posts I’m going to explain just what each little part of your home network is, how they work, and why they do what they do. Each device has a purpose, and those purposes are often quite specialized, even if they are combined into one plastic box that looks simple.

For starters, let’s talk about just what a network is.



At its most basic level, a network is simply a way for one computer to talk to another. Why you would do this will vary – in the earliest days of network design, it was mostly to prove it could be done and to build the foundation for future technologies, as research tends to go. In the 80s and 90s, as the internet got off the ground and became more popular, file sharing was the primary driving force; if everyone in your business could access the same documents without having to pass paper around, you had a leg up on the competition. At this point, dial-up modems and phone-based direct connections between sites were still the normal way to connect, but even though they used technology that is considered obsolete today, they were still “networks”. (As an aside, even a plain old telephone system can be considered a network, and the technologies share many functions despite the difference in usage.)

Nowadays, the primary reason to build a network, at least in your home, is probably to connect you to the internet. As the tech has marched forward, so the capabilities of the internet have increased nearly exponentially. The internet itself is a “network of networks”, and very much like the network of post offices here in the US, which each manage their own network of street addresses in their city, which each may have their own network of people inside, the internet is less a concrete thing and more a concept which grew out of the connections between individual homes and businesses in the early days of network research.


At their core, networks are actually quite straightforward. That’s not to say they’re simple, but the traffic follows a structured set of rules in order to do the job. Say you want to look at a web page, Facebook for example. In your web browser, you type “www.facebook.com” in the address bar and press the enter key. What happens next is always going to be the same basic flow, broken down and simplified here:

  1. Your computer asks the local DNS (domain name service) server  “I need to find www.facebook.com, what’s it’s address?” The DNS server replies with Facebook’s IP address. Your computer stores this in a cache so that it doesn’t have to ask the DNS server again for a while and is able to skip this step in the future.
  2. Your computer sends a request to Facebook’s IP Address, which is assigned to the web server for Facebook, asking for the default home page. This request (and all internet traffic, including the stuff in step 1) has both the source IP address (your router’s address, which I will explain in a later post), and the destination IP address, which is in this case the Facebook web server.
  3. Facebook’s web server sees that you have asked for the home page, and sends back several replies containing the home page. It knows where to send them because of the source IP address field in each request that you sent.
  4. Your web browser takes these replies and reassembles them into a page you can see on your screen.

There’s a lot more detail involved than this, but that’s the basics of an internet conversation. Facebook’s web server is a very specialized computer (most likely a cluster of networked computers, in fact), but in the most basic form it is just a computer, which is talking to your computer, in order to provide what you asked for (in this case, the home page).

All of this traffic (as its called) passes over the wires (and sometimes the air using wireless) of the internet through a massive web of interconnected routers. These routers are like the central distribution centers in the postal system, that determine where your traffic’s destination is and the most efficient way to get it there, and then forward it along to smaller routers/offices that can get it to your computer/mailbox.


So what is an IP Address?

Every device on a network has to have some sort of identification so that other devices know how to find it. There are two major systems in use for this purpose – MAC Addresses and IP Addresses. For simplicity, we’ll just ignore MAC addresses and move on to the most commonly referred ones: IP. An IP address is exactly that – an address. Like your home address, it can change (when you move, for example) – the IP address is not linked directly to the device.

An IP Address looks like this: 4 groups of numbers, each group between 0 and 255. There are certain rules these numbers have to follow which I won’t bother explaining. The important thing to know is that there is a distinction between public and private IP addresses. Private addresses are used in businesses and homes that have a router. Public addresses are used on the greater Internet on the outside of that router. In order to connect to the internet, your computer essentially has a private address AND a public address, and this public address is actually what the aforementioned Facebook web server sees when you send a request to it. The router does a little magic to make this work that I’ll talk more about next week.


The meat of how networks work can be VERY complex, and this only touches the surface of what goes on in some of the computers that run the internet, but I hope it gives a bit of a window into just how much is happening in even your basic home network. Next week, I’ll jump into just what a router is, and how it does what it does in your home.