A few people can believe in this now, but CDN technology was born not so long ago – in the middle of nineties. Less than twenty years ago, in 1996, the first patent for this technology was registered. Since then much has happened. First commercial Content Distribution Network operator appeared two years after the first patent – in 1998 year. After that and until nowadays, content delivery industry had come through several ups and downs. The biggest growth of technology use was observed in 1999-2000 years and in 2005-2006 years. The biggest fall of shares in this industry was in 2001 year. Now days there are twenty noticeable big players that sell technology and also plenty of small companies.
Due to a technology CDN, such networks consist of geographically distributed multifunctional platforms. If these platforms interact effectively between themselves, they can maximize their ability to satisfy user requests. Content Distribution Network pulls data on multiple servers to make it closer to the end user. When user makes a request and requested data is stored on some geographically or technologically close server, delivery network will satisfy such request without redirection to the origin server. If any of close servers have requested data, network will proxy the request to the origin server. The most popular decision of technology realization is caching. Such decision is most efficient in terms of space savings. It also uses network channels most effectively. The caching principle is to save only popular data on CDN servers. The more requests for a specific content user will make, the more servers will save it. Due to this principle, servers don’t have to store unused content data. When the first request for a specific data will come from the user, data will be loaded from the origin server. Other requests will already deal with CDN servers.
CDN web hosting usually assume, that content delivery companies have a lot of distributed edges. Some of them can locate their nodes directly in every local provider’s network. For example, such companies, as CaheFly and MaxCDN have 41 and 16 points of presence over the globe, respectively. Amazon CloudFront has 52 points of presence. CDNsun has even more -85 Pops all over the world – 25 in America, 44 in and 16 in Asia Pacific. Usually, the number of points of presence influences on a response and latency time, download speed and other characteristics. The more Pops company has, the bigger possibility that CDN server will be close to any user. However, some companies focus on communication capacity of channels and the minimum amount of interconnection points of presence in the region. Such companies have smaller amount of points of presence all over the world, but still preserve competitiveness. Every Content Distribution Network deals with request, distribution and delivery elements. It should take a request from user, decide whether it can answer and satisfy the request or proxy it. The optimal server for request it is not necessarily geographically closest. Such factors as server load, available ports and channels speed are also taken into account while network selects servers for request.