web site distribution

The full name of CDN is Content Delivery Network, that is, Content Delivery Network: CDN is a
second-level domain name, one is bound to one site.

DNS (Domain Name System, Domain Name System), a distributed database on the Internet that maps domain names and IP addresses to each other, enables users to access the Internet more conveniently without having to remember IP strings that can be directly read by machines:
Smart DNS has logic, which IP site a domain name goes to. nginx provides the same service.