Host names in terms of numbers are difficult to remember and hence they are termed by ordinary names such as Takshila or Nalanda. We write software applications to find out the dotted IP address corresponding to a given name.

The process of finding out dotted IP address based on the given alphanumeric host name is known as hostname resolution.

A hostname resolution is done by special software residing on high-capacity systems. These systems are called Domain Name Systems (DNS), which keep the mapping of IP addresses and the corresponding ordinary names.

The /etc/hosts File

The correspondence between host names and IP addresses is maintained in a file called hosts. On most of the systems, this file is found in /etc directory.

Entries in this file look like the following −

# This represents a comments in /etc/hosts file.
127.0.0.1       localhost
192.217.44.207  nalanda metro
153.110.31.18   netserve
153.110.31.19   mainserver centeral
153.110.31.20   samsonite
64.202.167.10   ns3.secureserver.net
64.202.167.97   ns4.secureserver.net
66.249.89.104   www.google.com
68.178.157.132  services.amrood.com

Note that more than one name may be associated with a given IP address. This file is used while converting from IP address to host name and vice versa.

You would not have access to edit this file, so if you want to put any host name along with IP address, then you would need to have root permission.