If the online store page does not open immediately, then the client will leave to look for goods in another online store, and the position of the site in the search will sag. If the movie freezes while watching online, viewers leave negative reviews on social networks and buy a subscription to another service. A CDN was created for fast and reliable delivery of any content to users.
Thanks to CDN technology, a physically hosted site in Moscow can be quickly opened by people from any corner of the planet.
Even if there are thousands of kilometers between them and the server where the resource is stored, let’s figure out CDN – what it is, how it works, and in what cases it is needed.
What is CDN: Look At Examples
CDN (content delivery network) is a unique system for accelerating content delivery to users.
For example, the server part of the application is located in a data center in Moscow, and the application users live all over Russia: from Kaliningrad to Vladivostok. The farther the user is from the capital, the longer the application exchanges data with the server and “slows down.” To speed uploading, the data that the application downloads is duplicated on servers located in different geographical areas. As a result, users quickly load the necessary data, regardless of the region.
Using a CDN, you can quickly deliver any content to users, for example:
- Static range of sites, mobile applications, games: images, styles, documents, banners, scripts, texts.
- Multimedia content: video, audio, live broadcasts.
- Dynamic range – changeable parts of sites and applications: user comments, news feed.
How Does A CDN Work?
The principle of CDN operation is as follows: the content hosted on the central server (source server) is duplicated on intermediate nodes; they are located in different geographical areas. The content is loaded not from the main server but from the nearest intermediate node when users visit the site. This reduces the loading time.
Let’s figure out how the content gets to the intermediate node. This happens when the first person from that region visits the site. For example, the area was opened by the first user from Novosibirsk. Immediately after its request, the content is cached on the intermediate node – that is, stored for other users.
Because the site’s content is requested from the central server in Moscow for the first user, it takes longer for him to download. But in the future, the intermediate node will not need to contact the central server. For other users from Novosibirsk, the content will be downloaded from an intermediate node, and the download speed will be higher.
Moreover, intermediate nodes can communicate with each other and cache content not from the central server but the nearest node. For example, when the first user from Seoul visits the site, the content is loaded to the local intermediate node not from the central server in Moscow but the node in Novosibirsk.