Why do you need a CDN?

After talking with a lot of specialists, the following problem arose: everyone knows that CDN is very good, it is correct, it is worth using. This article attempts to answer this question and explain in what cases a CDN can solve emerging problems and a number of technological and business problems.
Table of contents

Content availability

Quite often, every hour of downtime of an online store site is measured in very significant amounts. If the server on which the site is located failed at night, and the store must be available 24 hours a day (for example, due to the wide geographical coverage of users), then this can result in significant financial losses. A distributed network of servers makes it easy to solve this problem: if one of the available servers fails, then its place is immediately taken by the closest of the network neighbors. Thus, the end user does not notice any disruption to the site. In addition, data in a distributed network is also backed up on a large number of servers, which reduces the probable possibility of their loss to almost zero: for this it is necessary that the entire network fails at once, and this is statically impossible if it is not carefully planned by attackers in advance with the involvement of very expensive technological funds.

High download speed

Due to the fact that the network route between end users and servers with information is reduced to a minimum (and the servers themselves respond extremely quickly), the speed of requests will be very significant. As an example, the following figures should be given: the response time of a regular server located on a VPS (not even on shared hosting) is 50-200 ms (depending on various conditions, including the channel load). For CDNs, this number very rarely exceeds 10ms.

Reducing server load - source of information

The user load when using a CDN is distributed between the servers on the network, and the source server can only be used to receive information updates. If updates are extremely rare (and the site does not provide dynamic pages that depend on user behavior), then the source server simply does not need much power and can be replaced with a server of minimal configuration. Thus, the entire server load can be assigned to the CDN, and the main server will be responsible only for the relevance of the information provided.

Posting "heavy" content

In some cases (hosting software or media materials, creating interactive promo sites), the source server with information can be loaded with "slow" requests (which can last for minutes and hours, wasting server resources and preventing faster requests to get the rest information on the website). In this case, there is also only one way out - to use a CDN. CDN allows providing simultaneous servicing of tens and hundreds of thousands of "slow" requests without requiring additional qualifications from the staff responsible for the site with the original content. Carrying out a colorful promotional campaign, as a result of which it is planned to serve user requests for files of several (tens, hundreds) MB, it is worth paying attention to the network of distributed servers: it is guaranteed not to fail as a result of high load.

Resiliency and security

The CDN network is located on the most powerful technological platforms and has hundreds and thousands of servers, which increases the cost of an effective DDoS attack on it to fantastic values. If your business does not bring millions of dollars a day, then you can safely place your site on such a network and be protected from the attacks of unscrupulous competitors.

Scalability and load elasticity

A distributed server network has another advantage: it allows you to easily expand capacity, from serving 1000 people a day to several million or more. Thus, with a sharp increase in the load (a new product release, an article in a well-known publication, a promotional campaign), this will not affect the availability of your site in any way, its content will still be served quickly and without any interruptions.
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