There are many types of CDN networks and they all function slightly differently, but the basic function is the same. The end-user makes a request for a given piece of content. When they do the DNS look up for that link they are redirected to the CDN which performs an analysis to determine which node in the network is best suited to serve the content to that user. The determining factors are usually proximity to the end-user, both geographically and network, as well as load on the node server. Once a distributor node is selected a check is performed to see if the node has the content. If the node does not contain the content it pulls the content from the hosting customers Origin site (the server your site is hosted on) or from a NetStorage location and then caches and serves that content to the end-user. When subsequent end-users request the same content they are served directly from the distributor node creating tremendous increases in performance. Additionally, as more users request the content more and more servers are made available to serve it up, which is ideal for unexpected spikes in traffic such as a mention on Howard Stern, or a spot on the news. This can eliminate the need to upgrade your hosting service in order to handle these spikes. The CDN would handle it instead and scale as needed on demand.

This technology is something that just about every major mainstream site from Amazon to Disney has been implementing for many years. In the last few years the landscape has changed. The growth rate of content is changing and international users are becoming more prevalent. Content is being demanded in higher and higher quality. Image galleries, once the cornerstone of online content are no longer sufficient to draw new subscribers. It was once unrealistic to attempt to deliver HD content via the internet. With a CDN, delivering HD content is now a reality. The number of sites out there has increased significantly in the last few years and differentiation is becoming more challenging. Performance has now become an important factor and with the addition of high quality content the question of how to deliver it without significant load on the site or shoddy speed on downloads is fast becoming an issue.

There is some good news on this front. Large companies like Level 3 are investing significant money to build out dedicated content CDN and streaming networks specifically designed with the needs of the new demands in mind, and are creating partnerships with companies that have an intimate knowledge of the needs and concern of today?s web community.

Tour pages are the life blood of most pay sites and nothing is more important than users having a good experience through the tour. By utilizing a CDN you can ensure that they are not getting slowed down because of a spike in interest to the site during an affiliate promotion and this could lead to better conversions and happier affiliates.

Member content has always been a sticking point with CDNs because of the often complex authentication that needs to occur with the end-user before content is served, but the technology that is now available allows that process to be transparent to the user and keeps the content protected. This allows sites to serve up paid content as well as tour pages with the best possible performance to the end-user and taking the majority of the load off the content. It is not uncommon to be able to grow a site utilizing large amounts of bandwidth without adding additional servers to your existing hosting package.

Streaming is something many sites are split on today. Most sites use progressive downloads for their video content because delivering downloads is much cheaper and easier while setting up streaming servers and having enough servers to support multiple simultaneous users is expensive. Also as video quality grows performance becomes slow and network problems can cause tremendous latency and choppy playback for the user. With the new CDN technologies, streaming now becomes a viable option.

Streaming may actually save you money
With progressive downloads, if an end-user downloads a file and starts watching it, even if he only watches 2 minutes of a 20 minute clip the entire clip is going to download and your hosting bill will reflect the cost of the entire download. With true streaming the end-user is only getting delivered what he is watching and as a hosting customer, you are only billed for what was actually downloaded. Streaming CDN providers are able to handle hundreds of simultaneous streams and can deliver content from Net Storage locations making sure there is the lowest amount of latency no matter where the end user is.

Streaming is more secure
When an end-user downloads a file they have that file forever and can do anything they want with it including sharing it with others or putting in on their site. Streaming, especially with technologies like Flash and embedded video only deliver what the end-user is viewing and then discards it after each view. With the sudden increase in YouTube style sites it is harder to compete with your exclusive content if your exclusivity is compromised.

Streaming is going HD
Several of the major players have recently announced flash and Silverlight HD offerings to be rolled out this year, delivering extremely high quality content with great performance. This clearly is the wave of the future for delivering video content. Using a CDN for your HD streaming content is the best way to guarantee quality delivery of your content and a great experience for your end-user

Co-authored by Brian Lowy