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What is a content delivery network?

A content delivery network (CDN) is a collection of web servers located at various points within a network in order to maximize bandwidth and deliver content more efficiently to other users of the network. The server with closest geographic proximity or fastest response time is typically chosen.

Using a CDN can be costly, but as your website grows and draws more traffic from around the world, it becomes necessary to employ a CDN to reduce response times.

Websites that generate millions of views per day own their CDNs, but for the smaller business owner, it’s more cost effective to utilize a CDN service provider.

Why Are CDNs Necessary?

Static content hosted solely on your web’s server can slow down response times for viewers of your site. Spreading out static content over multiple networks by using a CDN can easily solve this problem.

Companies with highly traffic websites utilize CDNs to alleviate the amount of stress on their origin server. This in turn reduces the amount of bandwidth, thereby reducing operating and infrastructure costs.

Commercial CDN Solutions

There are several companies available that offer Internet hosting services. All work seamlessly behind servers that are well recognized by the general public:

Akamai: One of the largest CDNs in the world, Akamai works by mirroring content. This can include all data from a website including text, graphics, animation, or video, or just multimedia files. The Akamai server is then picked based on the user’s location and the type of content of the website. Some of Akamai’s clients include: Apple, Yahoo!, Adobe Systems, and J.C. Penney.

Limelight Networks: Akamai’s main rival, Limelight has been in existence since 2001. Limelight operates via fiber optic network, thereby removing the burden and traffic on the public Internet system. Just a few of Limelight’s clients include: Facebook, MySpace, Netflix, MSNBC, FoxNews, PlayStation Network, and Xbox.

Amazon CloudFront: Offered by Amazon WebServices, CloudFront was created to compete with Akamai and Limelight Networks. CloudFront has servers located throughout Europe and Asia as well as the United States. The service is pay-as-you-go, allowing you to try out the service without committing to a contract.

Peer-to-Peer CDNs

Peer-to-Peer (P2P) content delivery networks were in the center of media attention a few years ago, as clients were using these peer-to-peer networks to share copyrighted files illegally. Examples of well-known P2P CDNs are Napster, Kazaa, and Pirate Bay. Despite the misuse, CDNs use PSP to distribute large files without caching that data within their network. Users of the P2P help facilitate the data – by downloading the file, the user acts as another server by “seeding” the file (making the file downloadable by other users).

The two main problems with P2P is the lack of quality (HD) and ability for users to manipulate files by adding malware. The lack of quality is no fault of the system, but due to the fact that most P2P users do not have strong enough internet connections to download or upload HD video without the process taking multiple hours, or even days.

Free CDNs

The majority of companies who provide free CDN service operate by using P2P. While P2P can help lessen the strain on your server if you possess highly sought after (and original, of course) media files, they do not spread out static content to multiple geographic locations, and therefore will not provide the same quality of service as Limelight, Akamai, xpera group or Amazon CloudFront.

Without CDNs

CDNs help alleviate the burden on origin servers by relaying information from multiple points in the network. Without CDNs, there would be extreme bottlenecking, and heavily visited websites such as Facebook, CNN, or Google would take forever to access. If the Internet is the information highway, CDNs work as alternate routes to the same destination, thereby preventing massive traffic jams and increasing expediency.

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