Content Delivery Networks or CDN comprises of a series of servers and Points-of-Presence around the globe, which help in improving the page-load time as well as reduce the download time of the content by bringing it closer to the users. In the simplest way, a CDN can be explained as a set of mirrors for your website, hosted in such a way that the content is served to your targeted audience from the server closest to them.
Based on the technology, algorithm and the way in which the Content Delivery Network serves content, the CDN can be broadly classified into Peer-to-Peer (P2P) and Peering/Private based.
In peer to peer, the content gets cached at the peer’s end as soon as someone accesses the content and then onwards the peer’s system acts as a server. This allows the content to be shared from various sources instead of one. However, since peer-to-peer network can make the content be delivered on any ISP around the world and the content, it may not always choose the most optimal path.
In the peering based CDN, there are special Edge-servers owned by the Content Delivery Network service providing Company itself and these regionalized POPs around the world, which are directly connected with many ISPs to provide faster and better peering.
Apart from this, the Content Delivery Network providers also implement special algorithms and features like Anycast streaming for choosing most optimal paths for delivering content at blazing speeds.
Most of the professional Content Delivery Network providers including Akamai, Level 3, EdgeCast Networks, Internap, Highwinds and NetDNA use the peering methodology and have their own Points-of-Presence around the globe for delivering content.
Traditionally, the CDN providers help in both improving website performance and reducing server loads by offloading the static content like images, css and JS onto their edge servers. Apart from this, they also help in hosting the large files, media files and other rich content, thus improving downloading and streaming speeds.
However, with the web optimizations becoming more important and customers demanding faster performance, now many of the CDN providers have also enabled their networks to serve dynamic content from the edge servers itself. Nowadays Content Delivery Network providers have also combined Front-end Optimizations, minify, gzip compression and various other solutions to their original caching solutions to provide a fast-performing CDN offering for their users.