CDN explained for beginners

What is CDN?

CDN is the short acronym for Content Delivery Network, and it represents a large network of servers that are spread across different geographical locations. The main purpose of these servers is to cover a territory well and provide fast answers to the requests of potential users. All of the servers store the needed information, like images, video, code, in their cache memory. Additionally, they aim to be as close as possible to the users. As a result, the service is way more improved and quicker. Moreover, an extra positive effect of the CDN is load balancing. It improves the performance and reduces the load on the primary server.

How does it work?

The idea behind CDN is actually pretty simple. There are DNS recursive servers that examine from where the DNS request is actually coming. Afterward, they provide to the user the IP address of the server, which is located as close as possible. Oftentimes some service providers call these cache servers delivery nodes.

As we mentioned, the DNS servers are placed in very strategic locations. You are able to choose as many as you need and set even more in regions that are important. However, that depends on your DNS provider.

Compared to Anycast DNS, where the network of DNS servers holds an identical IP address, in the case of CDN is commonly used a GeoDNS service, also known as Traffic Director. This service allows you to use separate IP addresses for different locations. 

Thanks to that, all of your traffic won’t overwhelm the very same source. Additionally, you can set a second web hosting in the crucial locations. The servers are going to store the data in their cache memory, and you can set their IP addresses for the closest DNS server. The DNS request is going to receive a fast answer from the available and near cache server.

How to build your CDN?

You can create your CDN by having the following things:

  • Domain name/subdomain
  • Minimum of two servers in different locations. They could be dedicated or virtual.
  • GeoDNS tool for directing the users’ requests to the nearest server.

Advantages of CDN

It improves the loading time and minimizes latency. – That is possible due to having a server with the cached data nearby the users who initiate the requests. That allows the transfer and the loading process of images, videos, HTML pages, and other items to be extremely fast. The speedup of the loading time positively affects the user experience and SEO.

CDN improves your availability and redundancy. – The extensive CDN network with servers storing the data is extremely beneficial. In situations when a particular server is down, your website and content are still going to be available for your visitors. 

It improves security. – Extensive networks effectively spread malicious traffic when a DDoS attack is initiated towards your website, for instance. In addition, you can implement a DDoS protection service offered by some of the DNS hosting providers. 

Less bandwidth – The cached data allows your primary server not to deliver constantly identical content over and over again. Thanks to that, the amount of data transferred from your website’s host server is minimized.

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