DNS is distributed global naming scheme that maps human-readable host, machine or service names to InternetProtocol (IP) addresses.
So when you attempt to connect to a host name using the PING or TELNET commands, it is DNS that resolves the host address toa unique IP address.
For example, the command PING www.microsoft.com returns the IPv4 address 64.4.11.42. DNS provides mapping to both IPv4 and IPv6 addresses.
It can also provide the reverse service, mapping IP addresses to host names. Although DNS is the primary naming service on the Internet, where names are globally unique, organizations may also have their own internal DNS domains, where name mappings are local and the mapped IP addresses belong to private address ranges, such as 10.0.0.0/8, 172.16.0.0/16, or 192.168.X.X/24.