There are a large number of DNS servers on the Internet, constituting DNS domain namespaces. Each DNS server has its own domain name resolution responsibilities. Only when a DNS server cannot resolve a domain name itself, it forwards the request to another DNS server. Domain namespaces are managed by segment. That is, a large space is divided into several separately hosted zones.
Each public zone is a part of the namespace that is administered by a particular DNS server. For example, a DNS server is configured on the cloud platform to resolve all domain names in the namespace example.com.
Public zones are accessible to hosts on the Internet.