What is the CDN and its type characteristics

The full name of the CDN is the content distribution network. The purpose is to add a new network architecture to the existing Internet, and publish the content of the website to the "edge" of the network closest to the user, so that users can obtain the required content nearby and improve the response speed of the user visiting the website. .
CDN is different from mirroring because it is smarter than mirroring, or it can be used as a metaphor: CDN= smarter mirroring + cache + traffic diversion. Therefore, CDN can significantly improve the efficiency of information flow in the Internet. Technically comprehensively solves the problem of slow response time of users visiting websites due to problems such as small network bandwidth, large user access, and uneven distribution of network points.
CDN implementation is divided into three categories: mirroring, caching, and dedicated lines.
Mirror Site, the most common, allows content to be published directly for static and quasi-dynamic data synchronization. However, the cost of purchasing and maintaining a new server is high, and a mirror server must be set up in each region, with professional technicians for management and maintenance. For large sites, the bandwidth cost of the update is also greatly increased.
Cache, low cost, suitable for static content. According to Internet statistics, more than 80% of users frequently access 20% of the content of the website. Under this rule, the cache server can handle static requests of most customers, while the original server only needs to process about 20% of the non-locals. Cache requests and dynamic requests, which greatly speed up the response time of client requests and reduce the load on the original server.
Private line, allowing users to directly access the data source, can achieve dynamic synchronization of data.