The full name of CDN is Content Delivery Network, that is, content distribution network. The basic idea is to avoid bottlenecks and links on the Internet that may affect the speed and stability of data transmission as much as possible, so as to make content transmission faster and more stable. By placing a layer of intelligent virtual network based on the existing Internet based on node servers placed everywhere in the network, the CDN system can real-time according to the network traffic and the connection of each node, the load status, the distance to the user and the response time and other comprehensive information to redirect the user's request to the service node closest to the user. Its purpose is to enable users to obtain the required content nearby, solve the congestion situation of the Internet network, and improve the response speed of users visiting websites.