What is a CDN?

Content Delivery Networks Make Today’s Online Experiences Possible

Akamai What is a CDN? Video
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What Is a CDN?

A content delivery network is a highly-distributed platform of servers optimized to deliver content including web applications and streaming media. This network of servers is dispersed across many physical and network locations, in order to respond directly to end user requests for web content and fast, secure media delivery. It acts as an intermediary between a content server, also known as the origin, and its end users or clients.

Without a CDN, content origin servers must respond to every single end user request. This results in significant traffic to the origin and subsequent load, thereby increasing the chances for origin failure if the traffic spikes are exceedingly high or if the load is persistent.

By responding to end user requests in place of the origin and in closer physical and network proximity to the end user, a CDN offloads traffic from content servers and improves the web experience, thus benefiting both the content provider and its end users.

CDNs are mostly known for the delivery of websites and their content. User-agents, which are essentially devices running web browsers, make requests for content needed to render web pages such as HTML, images, CSS, and JavaScript files.

For most CDNs, each request for content will cause the end user to be mapped to an optimally-located CDN server and the server will respond with the cached (pre-saved) version of the requested files. If it fails to locate the files, it will look for the content on the other servers in the CDN platform and send the response to the end user. However, when content is unavailable or stale, the CDN will act as a request proxy to the origin server and store the fetched content to serve future requests.

Although the delivery of website content is a common use case for CDNs, it is not the only type of content that a CDN can deliver. In fact, CDNs deliver an incredible variety of content that includes: 4K and HD-quality video; audio streams; software downloads such as apps, games, and OS updates; data records that contain medical and financial information; and much more. Potentially any data that can be digitized can be delivered through a CDN.

A CDN provider is a vendor that provides businesses the ability to serve their content to end users across the world over a content delivery network. At Akamai, we take pride in being the world’s leading CDN provider.

As more businesses go online, and the world comes together on the Internet to shop, connect, and share, content providers face an increasing array of challenges such as: delivery of different types of content, adjusting content for different device types (device detection), and securing data and the online presence of their end users. The inherent capabilities of a content delivery network mean that CDN providers are uniquely positioned to help businesses overcome these diverse challenges of media delivery.

For almost 20 years, CDNs have formed the unseen backbone of the Internet delivering online content for retail, finance, healthcare, and other businesses to end users around the world with speed and at scale. If you’ve done almost anything online, you’ve benefited from a CDN – whether you knew it or not.

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