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What Is a CDN And Why Should You Be Using One?

At its core a CDN, or Content Delivery Network, does exactly what its’ name suggests – provides an efficient way of securely distributing web content to users across the globe. Information transfer isn’t instantaneous. If a user in Europe tries to connect to a web server in America, the data transfer is going to take a frustrating amount of time to travel, resulting in slow loading for the user.

To combat this, a CDN uses a global network of edge servers (often called ‘points of presence’ or PoPs) to distribute a cached version of popular content, sourced directly from the origin server. This offers users an alternative server to connect to that is much closer to their physical location, allowing for more rapid content delivery. This method of using an edge server as an intermediary from the origin server is known as a reverse-proxy. The edge server deals with the user’s request on behalf of the origin server to process the request quicker, while also evenly distributing the general server load generated by user traffic.

The Benefits of Using a CDN


One of the biggest assets a CDN can provide for a website to improve the overall user experience is speed. Over time, online user standards have increased when it comes to website speed expectations. High latency, slow loading time and unresponsive page speed can lead to an increase in bounce rates, un-engaged customers and if your business is eCommerce focused, a drop in profits. This rising demand for delivering a rapid user experience and providing an engaging yet functional platform can be a deciding factor in determining the success of a website. By using a CDN, the user’s geographical location can be taken in to account, allowing them to access a cached version of the website on an edge server that is closest to them i.e. the server that will supply them with information in the shortest time. This can reduce website load times significantly and ensure that all customers experience the same responsive website, regardless of location.


From a business standpoint, security and threat mitigation are arguably the most important things to gain from properly using a CDN. A DDoS (Distributed Denial of Service) attack is one of the many methods used by hackers to disrupt web services. This can be catastrophic for a business regardless of the size. It involves an attacker overloading a particular web server with more traffic requests than it can accommodate, often resulting in a reduction of performance or a crash, the latter of which leads to a total drop in service. This traffic is usually falsely generated by the hacker using a network of ‘bots’ or remotely controlled infected computers.

Storing web content on a singular server provides potential hackers with a very obvious focal point to attack, which can pose a serious vulnerability to your system. In addition to this, using only one server guarantees that if the DDoS attack is successful, all services are unavailable to genuine users until the server can be brought back online, often hours later.

When using a CDN however, you have an array of servers at your disposal to deal with user requests on behalf of the origin server. This use of multiple servers helps to prevent any one server being targeted and overwhelmed by a cyber-attack. Moreover, in the event that a singular edge server is focused and taken offline by a DDoS attack, you still have a network of functioning servers to fall back on so that web content can circulate as normal.

These edge servers, when integrated with a WAF (Web application Firewall), can work to differentiate between genuine user traffic and initial attempts at malicious attacks, including bogus traffic sent during a DDoS attack. During a malicious breach, the ability to detect early warning signs is often the best way to mitigate significant damage to a system. Having all traffic routed through WAF protected servers allows them to operate as checkpoints, vetting inbound and outbound traffic, and notifying you of any suspicious activity.


No matter what business sector your website falls under, ensuring that web content is always accessible, even during times of particularly high traffic, is essential. Specifically in eCommerce, increased rates of online sales can manifest around events like Christmas or Black Friday, resulting in sudden, unpredictable spikes in traffic levels. Without a CDN, this volume of traffic is funnelled directly into the origin server, putting it under significant strain as it tries to process all requests. The typical outcome of this is the server being overwhelmed, leading to a costly drop in services as well as a drop in sales while you try to get the server back online.

When using a CDN however, each request is processed separately by the nearest server to the individual user, effectively dividing the volume of traffic evenly across the network. This prevents any single server being exposed to large amounts of traffic, keeping all services running smoothly and your website accessible at all times. In the scenario that enough traffic is routed to a particular edge server to disrupt the service, there are other available servers that can pick up the slack to keep content delivery consistent. Additionally, because a CDN reduces the strain on the origin server it can help to reduce server maintenance costs by reducing the amount of general strain the server is put under at all times.

Types of CDN

There are two main types of CDN that have different functionality when it comes to distributing online content around the world.

  • Push: A Push CDN requires specific content to be manually pushed to the edge servers for users to access. Whilst this offers a you a lot of control about what web content is delivered and who it can be accessed by, it can also be increasingly time consuming as you regularly update your web content. This is especially true as your user base continues to grow and the demand for content become much more frequent and varied.
  • Pull: A Pull CDN dynamically pulls certain content to the edge servers automatically for users to access. This is usually the web content that is viewed most often. The automatic nature of this CDN is a huge advantage as it requires far less input than its Push counterpart, however it takes a lot of control away from the admin in terms of specific content distribution.


As online businesses continue grow and user-bases expand internationally, ensuring that you offer a streamlined experience and secure content delivery to all users should be a goal for any online business owner. Additionally, higher demand for e-commerce services as opposed to brick and mortar stores has increased the sheer number of users navigating the web on a daily basis. Properly utilising a CDN is a strong way of ensuring you are prepared to deal with this growing level of traffic at all times and that your content delivery remains consistent by negating the chance for overloaded servers.

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