CDN is the organization of content delivery with the main content present on the original web-server and with numerous POPs where this content is cached.
The main aims of any CDN are known to be the increase of speed, scalability, reliability and availability at any given point of time. Such networks are usually used to make the access to content much easier with minimal costs.
CDN is the system of severs that are strategically positioned across the globe. The client while trying to access needed data is automatically routed to the closest POP.
CDN can boast high performance. The content is cached on the severs across the globe and the decrease of the physical distance to client allows not only to make latency lower but also to lose less packets of data.
Scalability is also known as the advantage of CDN. The off-loading of traffic to CDN allows to adjust its volume easily, to increase or decrease it when needed in a very short time.
Reliability is very important too. The requests are usually sent to the closest location. If the server is unavailable, the next one is chosen.
CDN is also very good in terms of the fact that it does not require too much money to be managed and the reduction of costs can be made rather easily.
Nowadays most of clients need SEO-optimization and that’s why the page load time is very important – it is another factor that is considered when the page rank is calculated. Most search engines have page load time in their formulas.
Push zone or Pull zone?
Every user has a choice to use Push zone or Pull zone. But what is the difference? The push zone allows to load the content directly to CDN, as if you were using a generic hosting account. After it there goes synchronization in all POPs. It is necessary to underline that Push zones are usually ideal for big files.
Pull zone allows to cache static content from the primary server and to deliver it from POPs.
Every CDN can have additional functions. Let us give a more detailed view:
SPDY – the open network protocol. SPDY works with HTTP traffic and the main aim is the reduction of the time load of pages and enhancing the network security.
Secure Token – the special mean of authentification that ensure that URL is available for limited predefined time only.
Hotlink Protection – allows to ensure that files are loaded from predefined websites only.