Domain Name System

The Domain Name System (DNS) is a system used to convert a computer's host name into an IP address on the Internet. For example, if a computer needs to communicate with the web server "example.net", your computer needs the IP address of the web server "example.net". It is the job of the DNS to convert the host name to the IP address of the web server. It is sometimes called the Internet's telephone book because it converts a Website's name that people know to a number that the Internet actually uses.
The DNS is defined by Request for Comments (RFC) documents. These are technical documents about computer networks. The DNS is mainly defined by RFC 1034 and RFC 1035. There are later RFC which define changes to the system.
Structure.
Domain names are made up of one or more parts, or "labels" that are joined and kept separate by dots, such as codice_1.
Lookup process.
Let us imagine that a PC called "PC1" needs to connect to a server named "Server1". The following steps describe the basic DNS lookup process.
References.
4. DNS Server Not Responding Fix