What is a CDN?

A CDN, or content distribution network, is a system to deliver online data more efficiently by using a network of servers in various locations throughout the world or at least throughout the continent. CDNs also offer increased reliabilty by providing alternate routes for data to travel.

Content distribution networks vary in price range and in connections provided. Some are considered to be better than others for specific geographical areas, so where most of a website's traffic is from can be a factor in choosing a CDN. Also, the amount of data stored in each server can vary between CDNs, and each CDN may support different file formats.

How CDNs work

First, here's how content is delivered without a CDN:

  • A user enters a URL into a browser.
  • The request for data at that URL is routed through a varying number of servers until the request reaches the server where the website is hosted.
  • The data must then travel back the same route via the various servers until it reaches the user who requested it.

The further the target server is from the user, either in geographical distance or in hops required, the longer it takes for the requested page to download in the user's browser.

With a CDN, website data is replicated and stored at different locations in the network. When a request for data within the CDN is received, the data is sent to the user from the server in the network that can deliver it the fastest.

What CDNs are used for

Some of the following types of websites use content distribution networks:

  • Very large websites, for example, MySpace and Travelocity
  • Websites with high bandwidth requirements, such as video and download sites
  • Any website where speed and reliability are of the up most importance

The CDN industry

The content distribution network industry has experienced rapid growth since 2005 and is expected to continue growing. A key factor in its growth is the increase in online video content. Increased broadband use is another factor.

There are numerous CDNs on the market. Consumers can go directly to these companies for services. In addition, some web hosts and colocation providers have partnered with CDNs to offer content delivery network as part of their hosting plans.

See also

Web Hosting Wiki article text shared under a Creative Commons License.

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