CDN

What Is a CDN？

A content delivery network (CDN) consists of a group of geographically dispersed servers that accelerate the delivery of web content by positioning it closer to the end users.

CDNs use a process called “caching,” which temporarily stores copies of files in data centers around the world. This allows you to access online content from a server near you, reducing page load times and resulting in a faster, high-performance web experience. By caching content such as web pages, images, and videos on servers close to your physical location, CDNs enable you to watch movies, download software, check your bank balance, post on social media, or make purchases without having to wait for the content to load.

You can think of a CDN as an ATM. If your money were only accessible from one bank in town, you’d have to make a lengthy trip and wait in a long line every time you wanted to withdraw cash. However, with cash machines available on practically every corner, you have fast and easy access to your money whenever you need it.

As content providers began delivering more rich web content like graphics and videos over the internet, CDN services were created to address the problem of network congestion, similar to a traffic jam. Delivering content from centrally located servers to individual users simply took too long. CDNs have now expanded to include everything from text, graphics, scripts, and media files to software downloads, documents, portals, e-commerce, live streaming media, on-demand video streaming, and social media sites.

For over 20 years, CDNs have formed the hidden backbone of the internet, enhancing website performance and delivering online content for businesses quickly and at scale. Today, a significant portion of all internet content is delivered through CDNs.

How does a CDN work?

A content delivery network relies on three types of servers:

Origin servers

These servers hold the original versions of content and serve as the source of truth. Any updates to the content are made on the origin server. An origin server can be owned and managed by a content provider or hosted on the infrastructure of a third-party cloud provider such as Amazon’s AWS S3 or Google Cloud Storage.

Edge servers

Also known as "points of presence" (PoPs), edge servers are distributed across various geographical locations worldwide. They cache content copied from origin servers and deliver it to nearby users. When a user requests content from an origin server, they are redirected to the cached copy on the nearest edge server. If the cached content is outdated, the edge server fetches the updated content from the original server. These edge servers are owned or managed by the CDN hosting provider.

DNS servers

Domain Name System (DNS) servers maintain and provide the IP addresses for origin and edge servers. When a client requests content from an original server, DNS servers respond with the name of the closest edge server that can deliver the content more quickly.

A large portion of all internet content is delivered through CDNs. Here’s how it works in practice:

If you were in New York and wanted to visit the website of your favorite store in London, hosted on a server in the U.K., you would face slow load times if the request had to travel across the Atlantic. To solve this, CDN stores a cached version of the London website's content in various geographical locations worldwide, known as points of presence (PoPs). These PoPs have caching servers that deliver content close to your location in New York.

To ensure the best viewing experience, CDNs perform two key functions:

• Reduce latency: Latency is the delay you encounter when trying to load a web page or video stream on your device. Even though it's measured in milliseconds, it can feel prolonged and may cause load errors or time-outs. CDNs reduce latency by minimizing the physical distance content travels to reach you. Thus, larger and more widely distributed CDNs can deliver website content more quickly and reliably by placing it as close to the end user as possible.

• Balance loads: A CDN distributes overall traffic to provide the best web experience for everyone accessing online content. This is similar to traffic management in the real world. While one route might generally be the fastest from point A to point B, it can become congested if too many vehicles use it. Distributing traffic over different routes benefits everyone. Similarly, a CDN may direct you to a slightly farther server to avoid congestion on the shortest route. Load balancing helps content providers handle increased demand and large traffic spikes while maintaining high-quality user experiences and avoiding downtime.

A significant portion of internet content is delivered through CDNs, ensuring fast and reliable access regardless of your location.

The benefits of a CDN

CDNs handle a significant portion of global internet traffic, addressing the most challenging aspects of content delivery online. From small-scale content providers to multinational corporations, businesses worldwide leverage the essential benefits of CDNs to offer seamless web experiences to their clientele.

Enhance performance:

Performance defines the difference between instant access to new content with a single click and enduring a seven-second wait for a page to load or a video to buffer. This delay, known as "buffering," is represented by the familiar spinning circle icon on screens. To ensure optimal performance and minimize buffering, CDNs serve content pre-stored on nearby servers within their network, bypassing the need to request content from origin servers potentially located halfway around the globe. Even if content isn't pre-stored, CDNs utilize programmed knowledge of connections to navigate any challenges. Advanced CDNs employ additional technologies to address issues in delivering uncachable dynamic content and determine the suitable content type for various devices. With CDNs, content providers can offer fast, high-quality web experiences to all users, regardless of their location, browser, device, or network connection. This results in faster rendering of web pages, reduced video buffering, and increased engagement from website visitors.

Ensure availability

Availability ensures that content remains accessible to users, even during periods of high traffic or server outages in certain parts of the internet. When traffic peaks at millions of requests per second, even robust servers face immense pressure. Without a CDN, the content provider's infrastructure must absorb all traffic, leading to failures and subpar user experiences. CDNs offer widely distributed server infrastructures designed to mitigate these challenges. Advanced CDNs, with their highly distributed architecture and extensive server platforms, can handle over 100 Tbps of traffic, enabling content providers to remain available to even larger user bases.

Enhance security

CDNs can enhance website security by providing increased protection against malicious actors and threats like DDoS attacks. Leading CDNs offer unique cloud-based security solutions and DDoS protection to safeguard online assets effectively.

Gather intelligence

As carriers of nearly half of the world's internet traffic, CDN providers generate vast amounts of data on end-user connectivity, device types, and browsing experiences globally. This data empowers CDN customers with valuable insights into their user base, enabling informed decisions and actions. CDN intelligence also enables services such as real user monitoring, media analytics measuring end-user engagement, and cloud security intelligence to monitor online threats effectively..

Improve customer experiences

Content, application, and website owners, including e-commerce sites, media outlets, and cloud computing companies, leverage CDNs to enhance customer experiences, reduce abandonment rates, increase ad impressions, improve conversion rates, and foster customer loyalty.

Offload traffic

With the rapid growth of online streaming and rich media services, combined with heightened user expectations for web performance across various device types, many network service providers face significant strain on their content distribution networks. By serving cached versions of web content from servers closer to end users, CDNs can offload traffic from content servers, thereby enhancing the overall web experience.

Reduce bandwidth costs

By delivering content from servers in close proximity to users, CDNs reduce bandwidth consumption and associated costs.

Who uses CDNs?

CDNs, or content delivery networks, are ubiquitous in today's web infrastructure, catering to virtually every user accessing online content. Initially devised to optimize internet access by providing swifter and more dependable experiences, CDNs have evolved into indispensable tools leveraged by content and application owners, as well as network service providers, to deliver paramount benefits to their clientele.

For end users, the utilization of CDNs translates into expedited page loads, accelerated transactions, and a uniform online encounter. Despite the pervasive use of CDNs, many users remain unaware of their reliance on these networks as they seamlessly reap the benefits while accessing content through their Internet Service Providers (ISPs) or mobile providers. The covert operation of CDNs behind the scenes ensures users receive requested content swiftly and efficiently without discernible interruptions.

Content owners also harness CDNs to elevate customer experiences, thereby bolstering user satisfaction and loyalty. Furthermore, the integration of CDNs bolsters web security measures, offering fortification against cyber threats such as Distributed Denial-of-Service (DDoS) attacks. By leveraging CDNs, content owners fortify their digital infrastructure, safeguarding against potential disruptions and ensuring uninterrupted service provision.

In parallel, network service providers are increasingly recognizing the imperative of deploying their own CDNs. Such deployments not only mitigate subscriber churn but also pave the way for the inception of value-added services. By incorporating CDNs into their arsenal, network operators streamline traffic distribution, alleviate congestion on core networks, and unlock avenues to offer CDN services to enterprises and third-party content proprietors. This strategic integration empowers network service providers to optimize their infrastructure, enhance service quality, and expand revenue streams in a fiercely competitive digital landscape.

A fundamental advantage of CDNs lies in their capacity to offload traffic efficiently. By furnishing cached versions of web content from servers in closer physical and network proximity to end users, CDNs alleviate strain on content servers, thereby augmenting the overall web browsing experience. This approach not only ensures content remains within the network operator's domain but also diminishes the necessity for inter-network peering and minimizes reliance on broader internet connectivity for content dissemination.

In essence, the pervasive adoption of CDNs underscores their pivotal role in fortifying internet infrastructure and enriching user experiences. As technology advances and user demands evolve, the strategic deployment of CDNs will remain imperative for entities across the digital ecosystem to uphold service quality, ensure data security, and fortify competitive positioning in an ever-evolving digital milieu.