On the surface, the internet may seem to be a complicated web of computers spread throughout the world, but as the end-user, you probably will never notice it. You just open your internet browser, type in your question or website you would like to visit, and bam, in a blink of an eye, you're transported to that location. Now, you're probably thinking that looking any further into this subject would go completely over your head. So, let's simplify it and take an elementary look at how the internet works.

https://youtu.be/TnSgcPU7SU8

To examine this process, I will compare it to something you may be familiar with, the regular mail.

So, let's say we want to go to AppleGuideWeb.com. In this case, that's the name of the person we are sending the message to. Then, in the top left corner, we need to add our return address, in the form of a local IP address, like 192.168.1.20. This IP address is like a room number given to your device by your home router. Then, make sure you have pre-paid for stamps, a.k.a paid your internet bill. Finally, inside the envelope is what we are requesting from that site. Now, everything is ready to go except for one thing, the street address of AppleGuideWeb.com, AKA its IP address. For this, we are going to need help from the DNS.

The DNS, or domain name service, is like an address book. Throughout the World Wide Web, and even your home, there are address books that contain the names and addresses of every website.

First, your computer will check with your home router's DNS to see if it knows where AppleGuideWeb.com is. Since AppleGuideWeb.com isn't at your house, it's not going to know where it is.

So, your home router will pass the question to your preferred DNS provider and see if it knows where AppleGuideWeb.com lives. It's likely your network's preferred DNS is your ISP, or internet service provider, like AT&T, Comcast, Spectrum, etc. Each of these companies has their own address book to look up addresses. Then, if it's not there, they will forward it around until they find someone who does. But, somewhere in someone's address book is the address of AppleGuideWeb.com.

It's at this point that another technology is introduced, the CDN. A CDN, or content delivery network, helps a website in three distinct ways.

One, it brings the website closer to the visitor. For example, it would be very inefficient for AppleGuideWeb.com to be saved in one place. Imagine if it were only accessible by connecting to a computer in the middle of the US. Then, if someone from Europe wanted to visit, they would be sending data back and forth across the Atlantic. With a CDN in place, a copy of the website is saved to servers scattered around the world. This means that European visitors can connect to the much closer European copy of the site. And, whether you're connecting to the US or Europe server, you will get the same webpage and content.

The CDN also helps balance the load. Say you have thousands, or maybe millions of people, trying to visit a website. But, that server may not be able to support such a high volume of traffic. So, what does it do? It starts forwarding it to the next closest server.

Lastly, failover eliminates downtime. If one of the copies goes now for some reason, your visitor can be forwarded to the next closest version.

So, when your DNS is looking for the address of the site you're trying to visit, it's also trying to connect you to the copy that will give you the best results.

Here's another way to think of the CDN.