CDN (content distribution network or content delivery network) is a system of servers, which includes multiple data centers worldwide and across the Internet. Its main goal is to provide content to end-users with high performance and availability. Different CDNs play a significant role in a modern online content delivery. They work with web objects, such as text, scripts and graphics, store different downloadable content, such as media files, documents and software. CDNs also provide faster access to applications, live and on-demand streaming media, and social networks.