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The distance between a client and a server substantially affects the load times the client experiences. Based on that assumption, a sure way to maximize user experience would be to have multiple servers hosting the website in strategically placed locations around the globe. Although theoretically, this solution would work, in practice it would be quite inefficient. Hosting the entire website on multiple servers would just take up additional space without a good purpose. Therefore, a similar yet way more efficient and optimized method was created. It was named CDN, which stands for Content Delivery Network.
What is a Content Delivery Network?
A CDN, short for, Content Delivery Network, is a method used to deliver content from your website to its users more quickly and efficiently, based on their geographical location.
Simply put, it is a network of servers in many geographic locations that improve the delivery of static and streaming content. The CDN server that is geographically closest to the user that is requesting the content is named the ‘edge server’. When a user requests a certain webpage served through a CDN, its contents are stored on the edge server, making the latency between the nodes minimal. This ensures the best possible online experience for the user.
It does so by caching the content on multiple servers and directing it to users based on proximity. This content could be anything from web objects and downloadable objects to real-time streaming media. To find out more about CDN check out this article.
How Does a CDN Work?
To avoid the dissatisfied users created by slow service, CDNs move content closer to the user in order to reduce latency and improve the user experience. In theory, this is neat, elegant, and self-explanatory. In practice, however, there are some pretty gnarly technical challenges.
First, in order to reduce the latency for any particular user, a CDN must have a content caching server – a cache – that’s close to them. Unfortunately, it’s not feasible to have a nearby cache for every possible internet user. Instead, we organize the caches into PoPs, distribute them throughout large geographic regions, (Europe, US, Asia, etc.), and then place them in major population centers within those regions.
Next, given a request by a single user, a CDN must direct it to the closest POP. Most CDNs do this by leveraging a technology called GeoIP. GeoIP can be thought of as a large lookup table that maps IP addresses to geographic regions, (country, city, etc.). When a request is being processed, a CDN will reference the table and direct the user’s traffic to the closest available server.
What are the Benefits of using a CDN?
Websites that experience large amounts of daily traffic can use CDN to their advantage. Not only does it help reduce latency, but also takes some load off the origin server as the requests will be directed towards the CDN servers instead.
This is the main and most attractive feature of a content delivery network. Websites that opt for a CDN can have up to 50% reductions in load times, with certain cases getting even a higher percentage. CDNs supercharge your content delivery through:
- Minimizing the distance between the contents’ storage place and where they need to be sent.
- Reducing file sizes in order to optimize website loading speeds.
- Optimizing server infrastructure to respond to user requests more quickly.
As we all know, computers and servers are not perfect. Servers go down, networks become congested, and connections can get interrupted. A CDN allows websites to provide uninterrupted service to users even if any of the aforementioned problems arise.
Content delivery networks balance the load of network traffic, making sure that no one server gets overcrowded. If a single server does fail, a CDN can initiate a “failover” process that allows a backup server to take the lead.
The main way that CDNs cut down on expenditure for website operators is by reducing trips to and from the origin server. Because CDNs cache much of the content on a website and serve that content from the cache, the origin server does not have to deliver the same content over and over. Instead, the CDN does this on the origin server's behalf.
Web hosting providers typically charge websites for the data that gets transferred to and from the web host. The more data that gets transferred, the greater the cost. People often refer to these expenses as "bandwidth costs," even though "bandwidth" really refers to network capacity.
But when a CDN serves most of a website's content on the origin server's behalf, far less data needs to be transferred. Fewer user requests go to the origin server, because the CDN handles most of them. And less content goes out from the origin server for the same reason, lowering bandwidth costs.
It does not stop there however, using a CDN also improves your security as it provides DDoS and bot protection. It is the outermost layer of a website’s infrastructure and the first recipient of traffic. The attack is detected and blocked before it can even reach the origin server.
Lastly, a content delivery network has the ability to show real-time load statistics, optimize capacity per customer, display active regions, indicate which assets are popular, and report viewing details to their customers.
Now that you know what a CDN is and its advantages, you might think that setting up a content delivery network for your site might be a difficult endeavor, and to be fair, if you are doing everything yourself, then it definitely is. If you take the easier and more efficient route of having a professional service do it for you, however, a CDN is extremely easy to implement for most websites,
At its core, you only need to tell your content delivery network of choice which files (more often than not, it will be static resources) it should mirror and configure your site to send requests for these files to the CDN for handling. If you are using a popular content management system (i.e. CMS) such as WordPress or Drupal, you can utilize one of the many plugins that exist to set your site up to a CDN provider without much difficulty. Other implementations might require you to modify DNS records and change the name servers of your domain.
This has been an overview of CDNs and their advantages. We hope that with the help of this article, you were able to fully understand the concept of content delivery networks and decide whether you need a CDN for your website/web application or not. It is important to mention, however, that having a CDN is an absolute necessity if you have a site with 100,000+ monthly online visitors and wish to provide top-notch services to them.