Networks operated by content providers, that are optimised to deliver content to end-users. This is done by caching copies of content and being placed geographically close to end-users.
CDNs take advantage of DNS to intercept and redirect requests for which they have the requested content.
CDNs can be private, like Google’s data centres that are distributed all over the world and cache their content so that it can be provided faster to the end-users. Or they can be third-party CDNs that distribute content on behalf of multiple content providers like Akamai.
Approaches
Enter Deep: deploy many server clusters all over the world to be close to end users. This improves user-perceived delay and throughput by decreasing the number of Communication Links and Routers between the end user and the CDN.Bring Home: deploy a smaller number of large clusters that are strategically placed at places like IXPs. This results in lower maintenance and management overhead, but possible with higher delay and lower throughput.