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What is CDN technology, and who are the current CDN providers?

This tutorial on content delivery networks offers an overview of CDN technology, provides information on finding CDN providers and looks at CDNs' role in enterprise networking.

Enterprises are increasingly using content delivery networks, or CDNs, as they serve more static and dynamic content...

to users all over the world. A CDN is an interconnected system of servers placed at strategic locations, which are engineered by CDN providers to reduce the distance content needs to travel across long-haul networks to reach users no matter where they're located.

These distributed servers located at the network edge of the CDN contain cached content from the originating server. CDNs dynamically provide data to clients by calculating which server is located nearest the client and delivering content based on those calculations. This not only decreases the distance content travels from the originating company's WAN or a public cloud, but reduces the number of hops a data packet must make. The result is less latency, less packet loss and faster performance, which improves the overall user experience.

CDN providers house their customers' cached content in their own network points of presence (POPs) or in third-party data centers. When a user requests content from a website, if that content is cached on a content delivery network, the CDN redirects the request to the server nearest that user and delivers the cached content from the closest location -- a process generally invisible to the user.

Beyond placing caching servers at the network edge, CDN providers use load balancing and application performance techniques to help data reach users faster. These techniques include reducing file sizes using compression and special algorithms.

CDN services improve the performance and availability of both static and multimedia content -- including cloud and enterprise content -- for both desktop and mobile users. With a growing number of users accessing content cached on content delivery networks, CDN providers are also expanding their services to include security -- distributed denial of service, web application firewalls and bot mitigation -- digital rights management and customized content performance optimization services.

As a result, content delivery networks have become a more strategic business choice, rather than merely a way to store and cache providers' content. The expanded CDN services mix is causing many enterprises to re-evaluate their CDN deployment strategies and increase the mix of performance-based services they buy from a CDN provider.

Content delivery network illustrated

What you need to know about CDN providers

Rather than incur the expense of creating a private CDN, most enterprises use one or more CDN providers. CDN customers find they can improve site performance and pay less for data transfer because CDN providers offer pay-as-you-go services at considerably lower prices than what it would cost for enterprises to cache their own content at the edges of their WANs. Anyone looking to improve WAN performance or content delivery can use a CDN provider.

Dozens of companies now offer CDN services, with regional, national and global connectivity. Because it's rare that a single CDN serves every niche market or has POPs in every country or continent, most enterprises use more than one CDN provider to serve their needs, according to a Gartner CDN market report.

A representative list of CDN providers in this growing market include the following:

Why you need to know about CDN technology

A wide variety of organizations use CDNs to meet their businesses' performance and security needs. The need for CDN services is growing, as websites offer more streaming video, e-commerce applications and cloud-based applications, where high performance is essential.

CDN technology is also an ideal method to distribute web content that experiences surges in traffic, because distributed CDN servers can handle sudden bursts of client requests at one time over the internet. For example, spikes in internet traffic due to a popular event, like online streaming video of a presidential inauguration or a live sports event, can be spread out across the CDN, making content delivery faster and less likely to fail due to server overload.

Because it duplicates content across servers, CDN technology inherently serves as extra storage space and remote data backup for disaster recovery plans.

This was last published in May 2018

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