More and more companies use CDN’s system to work online now days. Content Delivery Network definition can be made in different ways. First of all, it is a distributed system of delivery servers. Such servers are deployed in multiple data centers over the global Net. Secondly, Content Distribution Network consist of multiple servers distributed over the globe to be geographically and technologically close to users. The other way how to perceive CDN – is to take it as a kind of cache. This cache consists only of a popular content.
CDN system can be constructed from a really big amount of edges. There can be thousands of servers related to dozens of Pops (Points of Presence). For example, such authoritative companies, as Amazon CloudFront and CDNsun have 52 and 82 Pops over the globe, respectively. These successful companies are usually represented on all continents. However, some companies increase their effectiveness in a different way – by improving their channels speed and servers bandwidth. Such companies usually have a few Pops, but are still competitive.
Geographic and technological proximity for distribution servers are concepts that include each other, but they are not interchangeable. Concept of geographic proximity realized by any CDN company presence in specific local networks.Technological presence also depends on presence in local networks. But it is also based on such concepts as server’s bandwidth and channel’s speed. Every time, when request comes to a content distribution network, system decides, which servers to use to satisfy this request. It can happen, that technologically closest server and geographically closest server will vary. In this case delivery network will use servers based on technological proximity.
Content distribution system must do such processes as reception, distribution and delivery. When any request appears, content delivery takes it. After that system decides, whether or not it can satisfy it. If delivery network can satisfy the specific request, it will use technologically available servers to work with a delivery. If there is no requested data stored in these servers, network will redirect the request to the origin server. Most of content delivery networks use the caching method to store important content. This method works very effective and prevents unimportant data storage. When first specific request comes to a CDN, user loads the required content from the origin server. The next time this specific request will appear, it will already work with content distribution network.
Authoritative CDN systems meet the most stringent security requirements. Customers can select the way, how the important data will be encrypted. Most of companies propose two ways of encryption: automatic and manual. Automatic way will use encryption (SSL protocol), which is installed in the specific content delivery company. It will be different from the user’s website encryption. Usually, this method of encryption can be simply turned on/off with just one button. The other side of security that CDN’s give – is the multiple backup, securely stored all over the Internet.