What is a Content Delivery Network?
WHAT DOES A CDN DO?
A CDN is a network of servers that are located in different places. So when a user calls up a website via a content delivery network, the website content is loaded from the respective server that is located at the next site. The loading time of websites or larger data packages can thus be significantly reduced.
Since communication traffic on the internet is global and thus takes place over long distances, an enormous increase in performance can be achieved by means of CDN. The web traffic to the main server is reduced and the bandwidth consumption is reduced - this means a clear improvement for the user experience, as waiting times can be minimised and actions on a website can be carried out much more pleasantly and quickly.
THE ADVANTAGES OF CDNs
A Content Delivery Network performs several tasks that improve website performance. These include the following in particular:
REDUCTION OF LOADING TIMe
In the long run, long loading times lead to the stagnation of a website's traffic, as users turn away. On the other hand, shorter loading times when calling up a page through CDN keep bounce rates low and increase the time spent on the page.
REDUCING BANDWIDTH COSTs
Every call to a website consumes network bandwidth, which adds up to significant hosting costs for the website provider. However, CDN services can reduce bandwidth costs by reducing the amount of data that a single server would normally have to provide through optimisations such as caching.
OPTIMISING WEBSITE AVAILABILITy
CDNs can prevent website outages that result from excessive traffic. Since website content is no longer retrieved from a single main server, but from a large number of globally distributed servers, the traffic is spread out. This minimises the risk of overloading the network hardware.
IMPROVING SECURITy
CDNs also improve the security of the website. A typical security risk is posed by attacks in which an enormous amount of fake traffic is generated on a website. CDNs handle such attacks by distributing the traffic across several servers, thus preventing the main server from being overloaded.
DEVELOPMENT OF CDN TECHNOLOGy
CDN technology gained particular relevance in the course of increasing audio and video streaming via the Internet - a development that has now become part of the everyday lives of the vast majority of people. In the course of this development, ever larger amounts of data had to be provided reliably and at high speed. Companies therefore increasingly used peer-to-peer networks and cloud computing technologies to ensure fast content delivery.
The development of CDN is far from complete. A large part of the web services are now centralised via cloud technologies, which corresponds to today's CDN standard. The next big development will be self-managing edge networks, where bandwidth consumption can be managed even more efficiently with the help of intelligent devices that communicate with each other.
HOW CDNS WORK
A Content Delivery Network consists of a federation of CDN edge servers, distributed in different geographical locations. The three underlying principles are caching, dynamic acceleration and edge logic calculations.
Caching
Caching is the process of storing multiple copies of a file or data package for faster access. CDN uses this principle by storing and serving copies of files on each of the different servers within the network. This involves static website content - this is constant, for example logos or fonts used on the website.
DYNAMIC ACCELERATIOn
Dynamic acceleration, on the other hand, refers to dynamic website content. These change depending on the location, settings or login time of the respective user - typical examples are local weather reports, chat messages or news. Dynamic acceleration reduces the retrieval time of this website content and, in contrast to caching, is designed for precisely this dynamic content. Unlike static content, the CDN server reconnects to the main server for each dynamic request.
EDGE LOGIC CALCULATIONs
CDN edge servers can be programmed to use logical calculations to optimise communication between the client (or user) and the server. In this way, content can be adapted to user behaviour, caching behaviour can be modified accordingly, and faulty requests can be detected and handled.
APPLICATION AREAs of CDNs
A Content Delivery Network is suitable for various application areas that benefit from the way files are stored and delivered. The following three examples show typical areas of application for CDNs.
HIGH-SPEED CONTENT DELIVERy
The delivery of both static and dynamic web content enables global news services to deliver their content to their customers worldwide at a high quality and speed. The globally distributed network of CDN servers meets the demands in terms of reliability and speed and also reduces the dependency on satellite communication.
STREAMING MEDIA FILEs
The major streaming platforms rely on CDNs to deliver their video content cost-effectively and reliably. Typical challenges such as reducing bandwidth costs, scaling flexibly and minimising load times can be overcome.
SCALING A LARGE NUMBER OF USERs
CDNs enable multi-user scaling that would not be possible with traditional website resources. The background: normally, only a limited number of client connections can be managed simultaneously. With the help of CDNs, however, large numbers of client connections are scaled and the servers are thus relieved.
A good example of this is provided by gaming providers who make their services available on various platforms and end devices and sometimes register millions of players per day on their servers. In addition, the data of these players must be stored and managed to enable a satisfactory gaming experience. A task that would be unimaginable without multi-user scaling through CDNs.