Content Delivery Network or CDN is an online infrastructure, which stretches around the world. Its main purpose is to distribute specific content via the internet, mainly on behalf of websites. This enables access to users in far off geographical locations, without reducing the quality of the service.
CDN is therefore an excellent way to speed up your portal, while making it available with a high performance even in completely different locations from where the main server is situated. This translates into a huge increase in visits to the site and, in a business context, a corresponding rise in the number of potential clients.
Why it is important to use a Content Delivery Network
Browsing a website with a hosting server (also known as Content Provider or Origin Server) with a geographical location which is far away from the user’s actual position, generally results in a somewhat negative experience. The portal becomes very slow, and the user encounters poor or even inadequate performance levels.
Such an experience causes most users to abandon the site, without even completing their search or even just a few seconds after they try to enter the site. From a business point of view, this means losing a potential client and therefore any return on the company’s investment.
What the CDN does is to create exact copies of the portal’s content and distribute the copied content to those requesting it. In this way, if a user in a distant location tries to access the portal, they can download the site from a server located somewhere nearby (Edge Servers), via a fast, high performance procedure.
The benefits of a Content Delivery Network can therefore be summarised as follows:
- Shorter loading time;
- Increased performance and improved user experience;
- Reduction in the number of users abandoning the site;
- Smaller workload for the origin server.
In order to work well, the architecture of a Content Delivery Network must follow a clearly defined system, which can be summarised in four essential points as follows:
- Content delivery: the combination of the origin server and all the edge servers in the CDN;
- Request routing: this involves directing the content requests to the best edge server;
- Distribution: carries out the process of copying content from the Origin to the Edge server and at the same time monitors its consistency (deadlines, updates etc.);
- Accounting: has the job of keeping track of all operations carried out and produces a log displaying the statistics and analyses needed for the administration of the portal.
Of all these areas, the most important is request routing, which is also the stage which involves the most interaction with portal web masters. This determines the way in which the content is replicated and sent to users. The two most important methods are DNS Redirection and URL Rewriting.
With the first method, the Edge Server substitutes the Origin Server completely and provides the user with an exact replica of all content. In the second case however, it is the web master who chooses which content should be copied by the CDN and then distributes it to the user via the Edge Server.
Both are valid methods and provide a level of performance which depends on the web master’s requirements. If the content of the site is mainly static (as in the case of a blog), then DNS Redirection is sufficient; if, however, the portal features continually changing content (as in the case of a social network), then URL Rewriting offers the best results.
Translated by Joanne Beckwith