Why CDNs are great for the Internet, and it's not for the reason you think

CDNs (Content Delivery Networks) are becoming increasingly popular. The obvious benefit is that they can help websites to give end users a speedier web surfing experience, but there is also another very positive side effect for the entire Internet, and it will become more noticeable the more common CDNs become.
The positive side effect is this: More CDN usage means less load on the Internet backbone.
Why? It all comes down to how most CDNs work.

Accessing a website that has no CDN

A regular website, with no CDN, serves all of its content from one static location, no matter where the website visitor is coming from. So, for example, if a European web surfer is visiting a website hosted in the United States, all the website content will be transferred from the American web hosting company across the Atlantic to the European user, via multiple network hops in both the United States and Europe.
Now contrast this with a good CDN, which will have multiple locations spread out over the world. It will make sure that content is always served from the location that is closest to the web surfer.

Accessing a website that has a CDN

When for example the European web surfer we mentioned above accesses the same site, which now uses a CDN, he will download the website content from a location in Europe, perhaps even in his own country. The data will only have to travel a fraction of the distance, with fewer network hops.
In other words: A much smaller part of the Internet infrastructure will have to be involved in the user’s interaction with this specific website.

Above: This is a visualization of the example mentioned in this article. Note that a much smaller part of the network infrastructure is used when the CDN is involved.
There may still be some data that needs to be transferred over the entire distance. Many sites only use CDNs for static files (for example images), but it will still greatly ease the load on the Internet backbone.
We suspect that 10 years from now, most web hosting solutions will have some form of built-in CDN, and this will be a Good Thing for the Internet.
What do you think?
Further reading: If you’re interested in some additional insights about CDNs, you might like to check out an article from 2008: A look at Content Delivery Networks, or “how to serve lots of content really fast”


  1. A cool little article. What do you guys recommend for a CDN? I know of Amazon S3 but is there some smaller website which is better that not many people have heard of? At the moment it seems to be massive CDN for big companies and Amazon for the rest of us.

  2. I’m aware of Akamai (the most well know/largest), Amazon S3, Limelight/Mosso Files, Internap CDN (as resold by Softlayer), BitGravity, LocalMirror, ValueCDN, CacheFly and Nirvanix.
    I do wish the CDN providers would give more details of where their locations are and example pricing.
    The cheapest for storing 10Gb of files and transferring 1,000Gb per month is Amazon (at $172), followed by Softlayer (at $180), but once you start getting more requests (or you have lots of little files), Amazon’s costs start going high (due to the fact they charge per request along with data transfer and storage).

  3. @Mac Tips: We usually don’t recommend any specific vendors, but Richy C probably answered your question to some extent. (Though the Amazon CDN is called Cloudfront, isn’t it? Though it integrates with S3.)

  4. Good post to explain in the most simple terms of what features a CDN has to offer. CDN is getting cheaper for those looking for bargains and let’s the “little guys” get in on the benefits of CDN technology as well.
    Another primary reason to go with a CDN is video streaming – whether that be static or live. Pusing your video through a true media server protects your content, speeds delivery and saves bandwidth.
    Randy Cooper
    Founder, CDN Evangelist
    Find out more on CDN from the blog where the CDN pros go!
    CDN Evangelist – http://www.cdnevangelist.com

  5. CDN is a great benefit for serving specific type of contents which need low ping travel times or dont get updated to much. Its completely useless for dynamic content that changes frecuently. Internet has moved from static to live content over the past years and this where CDN doesnt work, it would create exactly the opposite effect, overloading the network. Its great for streaming but not for on the fly content. I would ratter bet that in 10 years the CDN will be package based, not content or file based like it is now.. It will be based on the network layer where the same bit packages are just recreated from a shorter hub instead of being transfered over the whole planet. This kind of CDN which im investigating would replicate the data on the network level and the client would see the exact copy without the need to upload the data to the CDN hubs. The CDN would just replicate the data from a shorter path to each visitor. Currently CDN is just like having duplicated content on several parts. This can also be made by having our own servers on different datacenters and using a live replication technology with virtualization.

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