The Domain Name System (English: Domain Name System, abbreviation: DNS) is a service of the Internet. As a distributed database that maps domain names and IP addresses to each other, it can make people access the Internet more conveniently.
Domain name system DNS consists of three parts, namely address translation program, domain name server, and domain name space.
When an application process needs to resolve a host name into an IP address, the application process calls the resolution program and becomes a client of DNS, and puts the domain name to be resolved in the DNS request message. , sent to the local domain name server in the form of UDP user datagram (UDP is used to reduce overhead). After searching for the domain name, the local domain name server puts the corresponding IP address in the reply message and returns it. After the application process obtains the IP address of the destination host, it can communicate. If the local domain name server cannot answer the request, the domain name server temporarily becomes another client in the DNS and sends a query request to other domain name servers. Until a nameserver is found that can answer the request.
The jurisdiction of the DNS server is based on "zone". The area may be equal to or smaller than the domain, but it cannot be larger than the domain.
Domain name server division types:
Root domain name server (the most important), top-level domain name server, authority domain name server, local domain name server.
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