What is a CDN and why do companies use them?

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Services you probably use every day, from Netflix to Amazon, depend on something called a CDN or Content Distribution (sometimes “Delivery”) network. So what are these special computer networks for, and why are they so important?

The internet is a real place

It’s easy to think of web content like: Netflix steamy episodes or your Google Drive files being “out there” in the cloud. However, every piece of data has to be on a physical storage device somewhere, in a networked computer.

Trying to access a website on the other side of the planet will take much longer to load than a website hosted in your city or country. The further data packets have to travel, the more likely they are to hit a bottleneck as they go through interconnections, or they can just get lost. In that case, they must be re-sent.

Aside from the nuts and bolts of internet architecture, the important point to keep in mind is that the closer to you that content is physically hosted, the better your experience will be.

How CDNs work

CDNs comprise a series of servers spread over an area. They can be global or local, as long as they physically cover the areas where users are most likely to request content. The content provider uploads content to their server and then automatically distributes that data to the other nodes on the CDN network. CDN servers are usually interconnected via high-speed internet backbone connections, so it only takes a few seconds to move massive amounts of data between the servers.

CDNs are also smart and efficient. Let’s say you are the first person in your area to request a specific file from a website. If the file has not yet been replicated to your nearest CDN node, it will be copied there from the next node that has the data.

The local node will then keep the copy in case other local users want that file as well. If no one wants the file after a certain amount of time, it can be deleted until someone wants it again. In this way, the long distance bandwidth is used only once and then only local bandwidth is used. This is both faster and cheaper, so both the host and the user get a good deal.

The Benefits of CDNs for Business

CDNs do more than provide a good experience for users. They can save content providers money by avoiding overuse of expensive international bandwidth. CDNs can also accommodate large numbers of users, spreading the load across the network to ensure there is no denial of service. That also means that CDNs protect against malicious Distributed Denial-of-Service (DDoS) attacks.

In addition, CDNs provide a way to restrict content to areas where the content is licensed. It’s as simple as limiting locally hosted content to what’s licensed for that region.

Using a VPN beats CDNs, for better or worse

CDNs can go down from time to time, just like any web server. Usually, users are automatically redirected to the next CDN. If it doesn’t, you may get an error message stating that the service is offline when it’s really just that specific CDN node that’s the problem.

In that situation, you can use a VPN (Virtual Private Network) to make it seem like you are in a different region. This can be a quick fix for local CDN issues, albeit with a performance hit.

Unfortunately, when you use a VPN to bypass geographic content blocks, you lose the benefits of a fast local CDN node. Now you get your content from a remote node, which is then fed through an encrypted VPN tunnel. While many premium VPN services can still provide good bandwidth and usage latency, the quality of the service often deteriorates significantly.

Can anyone use a CDN?

It’s not just large companies building their own server networks that can leverage CDN technology. Most CDNs are owned by specialized companies that offer hosting and include CDN services as part of the hosting fee. Websites like Wix.com have their own CDN solution, so if you create a website with that service, a CDN ensures that people all over the world get fast loading times and overall responsiveness.

Individual users can take advantage of CDN technology by using products from companies that rely on it, but if you are a business user, you can also approach CDN providers directly. If you want to build your own CDN, it’s complicated, but not impossible. However, it is about more than just buying server hardware. You need a CDN software solution and the servers need to be installed in key locations (such as backbone connected data centers) for everything to work. Custom CDNs are absolutely best left to specialists.

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