The Wikipedia entry for CDN states: “A content delivery network or content distribution network (CDN) is a large distributed system of servers deployed in multiple data centers across the Internet. The goal of a CDN is to serve content to end-users with high availability and high performance. CDNs serve a large fraction of the Internet content today, including web objects (text, graphics and scripts), downloadable objects (media files, software, documents), applications (e-commerce, portals), live streaming media, on-demand streaming media, and social networks.”
Additional hops mean more time to render data from a request on the user’s browser. The speed of delivery is also constrained by the slowest network in the chain. The solution is a CDN that places servers around the world and, depending on where the end user is located, serves the user with data from the closest or most appropriate server. CDNs reduce the number of hops needed to handle a request. The difference is shown in the following figures.
CDNs focus on improving performance of web page delivery. CDNs like the Akamai CDN support progressive downloads, which optimizes delivery of digital assets such as web page images. CDN nodes and servers are deployed in multiple locations around the globe over multiple Internet backbones. These nodes cooperate with each other to satisfy data requests by end users, transparently moving content to optimize the delivery process. The larger the size and scale of a CDN’s Edge Network deployments, the better the CDN.
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