CDN is a content delivery network. A system designed to speed up content loading at the end-user. Using CDN allows you to speed up the loading of static content, and improve the SEO characteristics of the site. In this article, we describe how CDN service works and why it is important.
Why use a CDN
Imagine opening two websites at the same time. One loads quickly, while the other has not yet loaded images or other content. Which site would you rather use? Probably the first one. The second will lose a significant portion of new visitors and annoy regular users. 75% of users decide whether to stay on the site within 5 seconds. This applies to those who visit the site from a computer. Mobile device users leave slow sites even faster.
For a user, it is not a problem, because he can find information on another site. However, for the owner of a slow web resource, the loss of visitors is a disaster. Potential customers are lost, search engines decrease the site's rating, and advertising budgets are wasted.
Since the sites open simultaneously, the problem is not the Internet speed, the browser, or a computer. This means that something is wrong with the server. Is it possible to solve this problem and speed up uploading? Yes, with the help of cloud CDN. Interconnected servers located all over the world allow content to be delivered to a user's device quickly, no matter how far the source of content is from the end user's device.
Benefits of using a CDN
Improving upload speed. Content Delivery Network minimizes the network route between the content source and the user. With this technology, the response time of the source server rarely exceeds 10 milliseconds. Content is equally responsive everywhere.
Reducing the load on the source server. With the Content Delivery Network, the load is distributed across all servers in the network. The source is involved only in distributing updated data and settings to the network. If there is no dynamic content and updates are rare, hosting costs will be low and performance requirements minimal.
Increasing website availability. CDN servers provide redundancy for each other. If one of these servers fails, traffic will go through the others. Fault tolerance is ensured even during DDoS attacks.
Hosting content-heavy websites. If the site contains resource-intensive software or interactive media files, the source server can be overloaded with requests that take minutes or sometimes hours to process. Thanks to CDN, it is possible to handle the required number of requests at once.
Improving SEO. Website speed is an important search engine ranking signal. If a website loads too slowly, it can lead to user loss. It also affects behavioral factors. Google research has shown that by increasing the page load time from 1 to 10 seconds, a visitor is more likely to leave the site. With CDN, the site is more responsive and users are more likely to stay there. The number of bounces decreases, resulting in search engines prioritizing the resource in the results.
Standard web hosting transfers data in the following way:
- The user opens a website or web application.
- The browser sends a request to the source server.
- The server receives the request, processes it, and sends a response back.
- The page loads.
CDN provides additional storage and transfer points to this scheme. The uploads are accelerated by caching and shielding technology.
Caching means storing copies of files in a cache, or temporary storage so that they can be accessed more quickly. The content delivery network caches content on proxy servers that are closer to end-users than the original servers.
Since the servers are closer to the user making the request, CDNs can deliver content faster. If a user from Russia visits an American site, the content will be downloaded not from an American server, but, for example, from a European one. This directly affects the load speed.
Content may be of any kind: pictures, videos, JS scripts, and much more. Streaming services like Netflix could not exist without CDN – the delays would be too big.
It is important to understand that content is not cached instantly. It may happen that the content has changed on the source server, but not on the caching one. For this purpose, the administrator should provide several algorithms. For example, setting up prioritization so that important content is loaded fast or forcing content to be placed in the cache immediately after an update.
Shielding is another technology that protects the source server from overloading. The idea is very simple: an intermediate server is installed between the source and the CDN, which first caches the content and distributes it to other servers in the content delivery network.
Which websites can benefit from using a CDN?
CDN is crucial for large projects with audiences across different cities and countries. For example, such as development or advertising platforms. Also, a content delivery network will be crucial for the online resources such as:
- E-commerce websites with visitors across the world.
- Streaming services (Netflix, Spotify).
- Game portals offering cloud gaming services.
- Software distributors.
Checklist for choosing a CDN provider
Find out the number of points (caching server locations), and the coverage area size. The more points of presence and the wider the coverage area, the better.
Find out how your interaction with a service provider is organized. The points of presence (POPs) in several locations do not always guarantee a high loading speed. What also matters is the number of connections with a service provider.
Check out the control panel and its functionality. The availability of a user-friendly control panel and a good set of tools is an important indicator of the quality of the service offered. Flexibility and usability mean that CDN-provider specialists are constantly improving the service.
Ensure security. The site and caching CDN servers must be protected. Usually, a cryptographic SSL certificate, HTTP/2, and IPv6 protocols are used.