What is CDN and where it can be used?

CDN (Content Delivery Network) is a network infrastructure that optimizes the delivery of data to end users through linked sites or points of presence (PoP) located in different geographic regions. This ensures load balancing by processing requests closer to users, which ultimately provides a faster speed for visitors of a web resource.

How it works

When using regular hosting, the browser of the visitor to the Internet resource interacts directly with the client hosting, where all data is stored. CDN adds intermediate links to this chain in the form of special caching sites scattered around the world.

The network of data centers stores the cache or portions of the files for the quick delivery to end users. And even if the client site is hosted in New York, a visitor from Japan can surf the website with minimal delay, because he will get the cache of the web page from the closest point to him.

Advantages of CDN 

The technology has a number of advantages: 

• High loading speed. Since the distance between consumers and hosting servers is reduced to a minimum, the response time rarely exceeds a fraction of a second.
• Reducing the load on the main server. Since the traffic is evenly distributed between network elements, client infrastructure is used only for syncing and changing settings.
• Handling of "heavy" media files. Resource-intensive content (e.g., video) is fetched by end-users in batches as it is downloaded. This leads to channel overload, especially if the user's Internet connection is slow and the content is downloaded in small chunks. With Content Delivery Network, fragments are stored on network servers, which allows you to handle tens or hundreds of thousands of requests, regardless of their size, without lags.
• Fault tolerance. The structure can consist of hundreds of points of presence distributed across countries and continents. With this configuration, the system provides significant redundancy of cached data storage.
• Scalability and reliability. CDN is virtually unlimited in the number of requests and expands as the load increases. The peak of millions of sessions will not affect the availability of information, it will be synchronized without any disruptions. And even in case of an emergency, users will still have access to static content on their local Point of Presence.

Promotion of the site in search results. Long loading of a web page affects user experience, which significantly reduces conversion rates and increases the number of bounces. This leads to a decrease in the search engine ranking. Distribution of requests between data centers improves conversion and, as a consequence, affects the position of the resource in the top search engine.

When CDN is a must-have?

Now, when we know what a CDN is, let's discuss who needs it. CDN is an excellent choice for IT-projects which have a wide audience from remote corners of the world. This network technology increases reliability and speed of downloading at any volume of incoming stream. It is impossible to imagine a modern game portal, or a popular mobile app without it.

In the last decade, streaming services, which allow you to play information directly from the Internet, have become widespread. Online broadcasting of movies or sports events in good quality, listening to music became a norm for millions of users. Content is no longer stored on devices, it goes online and CDN has become a real salvation for such projects.

However, this approach is not necessary for ordinary websites that don't involve extensive geography or one-step sending of "heavy" files.  A business website of a company operating in the California area which is hosted in Los Angeles doesn't need a CDN. If you face long "rendering" of your website in the browser, most likely, there is a problem with the code, not with the network.

Specifics of the technology  

When using a content delivery network, you should understand the principles of its operation in detail. When choosing a provider, you may encounter different algorithms that determine which data center to contact. They are based on two main web technologies - AnyCast and GeoDNS.

The difference is that with AnyCast, the connection is routed to the closest points of presence at a dedicated address. The website visitor's ISP receives route announcements to the CDN and provides an optimal path connection. If the connection is lost, the client will connect to the next closest PoP. This technology is based on the BGP protocol, which is the basis of all the redundancy and route selection on the Internet.

With GeoDNS, IP addresses are assigned according to the point of the user's presence. CDN determines the location of the sender and forwards it to the closest server based on geographic location in accordance with pre-defined rules.

CDN providers. How to choose?

CDN services are provided by a number of local and global companies. To avoid making the wrong choice, you should pay attention to the following:

• Type of content. Different data requires different bandwidths. Streaming and online games require a wider channel than for a static content. However, it will be more expensive. 
• Location of the main audience. You need to determine where most of your users are coming from. And then see if there are CDN PoPs in these regions.
• Data transmission security. It is important to make sure that the CDN supports TLS (transport layer security) certificates, and allows you to use your own SSL certificate.
• Flexibility of the settings. The more options you have in your control panel, the more effectively you can optimize traffic routes and increase the speed of delivery. 
• Tech support. The speed and proficiency of the support will determine the reliability of your service, and therefore the revenue. Having 24/7 support will be a great option.
• Pricing and a trial period. Pricing and a trial period. For many web projects, the cost becomes a major determining factor. It is better to calculate the estimated budget in advance, taking into account CDN costs. In addition, some providers offer a free trial period to get acquainted with their services.

Melbicom has its own CDN network with data centers located on all continents in 36 countries. We offer caching of static content and video files, full support for the HTTP/2 protocol and detailed statistics for all of our tariffs. Thanks to the brotli-compression protocol, customers and visitors can save a lot of their budgets on traffic.

Summing up the results

What is CDN? It is a great solution, thanks to which a subscriber from Bulgaria can easily watch a new season of "Paper House" on Netflix. Content Delivery Network makes the Internet more accessible. It is becoming the basis of many modern IT solutions: marketplaces, streaming platforms, and game portals. This web technology speeds up site loading and ensures the continuous operation of Internet projects. There are many offers on the market, but if your project is aimed at a small, geographically concentrated audience and does not involve the constant transfer of "heavy" media files, think twice about the reasonability of using CDN. After all, you have to pay for everything.