 A content delivery network or content distribution network CDN is a geographically distributed network of proxy servers and their data centers. The goal is to distribute service spatially relative to end users to provide high availability and high performance. CDNs serve a large portion of the Internet content today, including web objects, text, graphics and scripts, downloadable objects, media files, software, documents applications e-commerce, portiles live streaming media, on-demand streaming media, and social media sites. CDNs are a layer in the Internet ecosystem. Content owners such as media companies and e-commerce vendors pay CDN operators to deliver their content to their end users. In turn, a CDN pays ISDs, carriers, and network operators for hosting its servers in their data centers. CDN is an umbrella term spanning different types of content delivery services, video streaming, software downloads, web and mobile content acceleration, licensed slash-managed CDN, transparent caching, and services to measure CDN performance, load balancing, multi-CDN switching and analytics and cloud intelligence. CDN vendors may crossover into other industries like security, with DDOs protection and web application firewalls with and want optimization.