Domain Name System

The Internet is a vast collection of servers, each storing websites and other resources. Every server — indeed every device connected to the Internet — has a unique IP address. To visit a website, you would normally need to type that IP address into your browser. But IP addresses are strings of numbers (or, in IPv6, hexadecimal strings) that are hard for humans to remember.

Names, on the other hand, are easy to remember. So each server that hosts a website is given a human-friendly name, called a domain name (or hostname), which is mapped to its unique IP address. This mapping is the core idea of the Domain Name System (DNS).

Think of DNS as the phonebook of the Internet. Instead of memorising every person's phone number, you store their name and look up the number when needed. Similarly, DNS lets you type a domain name like ncert.nic.in and automatically finds the corresponding IP address (e.g., 164.100.60.233) so your browser can connect to the right server.

The textbook gives these examples of domain names and their mapped IP addresses: