Why You Need a Content Delivery Network

Everyone paying for web hosting has one aim in mind: maximize speed, improve uptime and minimize cost.

Finding the right host for your site helps. So does picking a good company to host with.

But you still have to optimise your content.

A content delivery network (CDN) can greatly increase the speed and reliability of a site while helping to keep costs down. Many website owners simply don’t know how to implement a CDN, or are put off by the fuss of setup.

Let’s explore CDNs in more detail.

The Geographic Benefits Of a CDN

Let’s imagine our site is on a server in San Francisco. If we get a visitor from Los Angeles, the data they request only travels a few hundred miles, so it’ll take a fraction of a second to be transmitted.

If the visitor is in New York, the transmission takes longer.

If the visitor is in Paris, Moscow, Beijing or Sydney, the connection will be slower still.

Content delivery networks duplicate the same data in datacenters all over the world. The CDN automatically selects the closest one when a visitor hits your site.

So a visitor in Beijing may get the data from Hong Kong, but a visitor in Paris might get your content from London.

Since most CDNs use large networks of servers, downtime is kept to a minimum. If there is a problem at one datacenter, the traffic can be routed to another.

Does it Work?

In this screenshot, half of the images were hosted on a CDN and half were not. The difference in loading time is clear.

Some optimisation specialists believe that search engines, seeing that the site loads more quickly, favour sites that use CDNs.

Choosing a CDN

Note: this information was correct at the time this article was published in April 2009.

Setting up a CDN is not only inexpensive, it’s a project you can complete in a few hours.

Most consumer-oriented CDNs are targeted at serving static content: images, JavaScript files, CSS files, etc. The CDN sits alongside your hosting account, relieving some of the load from your server and potentially saving you money.

There are two major providers that are consumer-facing: Amazon S3 with CloudFront and Rackspace Mosso. Both provide essentially the same service with comparable pricing, though Amazon customers have access to more tools. Smaller competitors such as GoGrid and SimpleCDN toffer lower prices and additional features, but are generally less established.

All of these services work fundamentally in the same way.

Using a CDN

If you’re a WordPress user, look for Amazon S3 or Mosso plugins.

If not, you’ll follow this procedure.

1. The user uploads his or her files through a web interface or a compatible application.
2. They check that the files are viewable and the CDN is serving them.
3. The user may then edit their DNS settings to use a subdomain name to point to the hosted files, making the CDN invisible.

The Cost of a CDN

Note: this information was correct at the time this article was published in April 2009.

Pricing varies wildly from service to service. But CDNs, typically, do not charge a monthly fee.

Most CDNs start at about 17-25 cents per GB of transfer, plus a small amount per X number of requests (in some cases). Small sites typically pay pennies per day. Large sites often still benefit, because a CDN is normally cheaper than a higher capacity hosting account.

That’s sites like Twitter, Drop.io and Scribd all use a CDN.

Is It Time to Switch to a CDN?

CDNs are inexpensive and could offer benefits: performance boosts, lower resource usage and maybe a better search engine ranking.

Don’t be intimidated by the setup procedure. Dedicate a day to selecting and installing a CDN. You’ll almost certainly see a benefit within a matter of days.