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CDN Architecture

Updated on October 4, 2018
CDN Architecture

As today's technological needs evolve with the requirement to deliver various content at high speeds, CDN architecture must be designed to meet those demands. Everything from distributing resource-intensive media files to minimizing the load time for a website's static files is important for both the content owners and the content viewers. Having the proper CDN architecture in place helps to ensure that users across the globe are receiving optimized content delivery.

A CDN's points of presence (POPs) play a major infrastructural role since the caching mechanism depends on the reliability and effectiveness of these servers. KeyCDN works with various partners and we are continuously expanding our list of POPs to offer state-of-the-art CDN infrastructure.

What is a CDN and how does it work?

For those who are unsure of what a CDN actually is, we've written an article to address this, what is CDN? In brief, a CDN, or content delivery network, is comprised of a cluster of servers strategically placed across the globe with the purpose of caching site content for faster delivery.

KeyCDN's CDN architecture provides the ability to optimize content in 2 separate ways - Pull Zones and Push Zones. Although not all CDN infrastructure is built to accommodate both methods, each has their strong points and are useful in different situations.

Pull Zone

A Pull Zone automatically pulls the static content from your origin server and creates a copy that will be served to users upon subsequent requests. This is convenient when wanting to quickly integrate a CDN with a particular website without having to manually upload anything.

Push Zone

A Push Zone on the other hand, places uploaded content on various storage servers across the globe and pushes content to the POP upon user request. This method is recommended if wanting to deliver content that is greater than 10 MB in size via the CDN. Each method has its pros and cons depending on what the optimization scenario involves.

Taking advantage of CDN architecture

As mentioned, reduced latency resulting in a faster loading website for users is one of the main benefits of using a CDN. However, there are also other important advantages to using a CDN's infrastructure for content delivery. For example:

  • Downtime protection and reliability: CDNs take a large load off the origin server allowing for easy scalability in case you receive a sudden spike in traffic. CDN architecture is designed to handle very large amounts of bandwidth usage by providing ample resources and networking capabilities. This allows for more users to access the website while minimizing the risk that the origin server gets overloaded. CDNs also help increase reliability as if one POP goes down, traffic gets rerouted to a different POP - increasing redundancy.
  • Increased security: With the amount of servers a CDN has to offer, a website that is using a CDN also benefits from increased security from things such as DDoS attacks. Many CDN's, including KeyCDN, have infrastructure built in to help mitigate the risk of attacks. CDNs may also provide additional security features such as the ability to install SSL for a secure connection between the CDN servers and the end user and the ability to create Secure Tokens.
  • Improved SEO: A cross benefit from a faster loading site which results in a better user experience is that it also helps improve SEO. As Google uses site speed as a ranking factor in their algorithm, having a speedy site will also help move you up in the SERPs. Reliable and modern CDN architecture allows for increased speeds by implementing improvements such as HTTP/2 and SSD-optimized servers for even faster content delivery.

These additional advantages help enhance various aspects of a website overall. For a more detailed description of the advantages of a CDN and why you may want to use one, read our article 7 Reasons You Should Use a Content Distribution Network.

Highly distributed vs simple CDN topology

In order for CDN infrastructure architecture to be effective, it should have high performing POPs distributed across the globe. This allows for most users to access information much faster than if a request was sent to the origin server each time. CDN topology can vary depending on the CDN provider. Some providers opt to employ a vast amount of low-capacity servers in select geographic regions, while others strategically place a lesser amount of high performing servers across the globe.

The number of nodes and servers making up a CDN varies, depending on the architecture, some reaching thousands of nodes with tens of thousands of servers on many remote points of presence (POPs). Others build a global network and have a small number of geographical POPs.

- Wikipedia

Legacy CDN's were built on the premise that more POPs were better, no matter if the servers themselves weren't very powerful. However, this method can hinder the response time of configuration deployments. Moreover, as Internet connectivety improved thanks to certain advancements (fiber cable for example), POPs located in such close proximity were no longer needed. Now, many CDN providers offer a medium number of high-capacity POPs spread globally - described as simple CDN topology. Simple CDN topology also helps improve against attacks such as DDoS since they can handle much more traffic.

KeyCDN currently has strategically distributed a global network of POPs within our CDN architecture consisting of servers spread across the Americas, Europe, and in Asia and Oceania. New POPs are regularly added within the KeyCDN network to help improve the overall global delivery of a website's static content.


High performing POP servers and reliable infrastructure is essential to solid CDN architecture. By providing strategically distributed servers across the globe, CDNs are able to bring web content closer to the user while additionally, reducing bandwidth consumption, increasing security and much more. When searching for a CDN provider, be sure to look for a few important components including:

  • HTTP/2 support
  • 100% SSD-optimized edge servers
  • A healthy distribution of POPs

Having insight into a CDN's architecture in respects to where their POPs are located and if their servers are high performing can help provide greater insight in regards to the reliability of the CDN.

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