DNS | What is DNS | How does DNS work | Components of DNS | Purpose of DNS | Explain with animation

DNS stands for Domain Name System. It's the internet's directory, connecting web browsers to web servers by mapping human-readable domain names to machine-readable IP addresses, similar to a telephone directory.

The main purpose of DNS is to map IP addresses to names and vice versa, as humans find it easier to remember names than long strings of numbers. DNS uses port 53 and primarily relies on the UDP protocol for its speed, as immediate responses are often required. TCP is used in specific cases, which is posed as a question for the audience.

Domain names are the locations of websites. They are categorized into three main types: Generic Domains (e.g., .com, .edu, .gov), Country Domains (e.g., .in, .au), and Inverse Domains, which map IP addresses back to domain names. Each type has a hierarchical structure within the DNS tree.

DNS uses hierarchical namespaces, which provide a flexible naming structure unlike flat namespaces. In a hierarchical system, the root node connects to top-level domains (generic, country, inverse), which are further divided into second and third-level domains, making it easier to manage and locate websites.

A DNS name server stores DNS records and acts as the 'phone book of the internet'. It connects URLs with IP addresses. Servers can be primary (responsible for a zone's files) or secondary (load information from primary servers). A 'zone' refers to a server's database, and the root server oversees the entire DNS tree.

The name resolver is client-side software used for mapping domain names to IP addresses and vice versa, operating within a client-server architecture. Resolution can occur through two methods: recursive (where the server fully resolves the query) and iterative (where the server provides the next server's address for the client to query).

When a user enters a URL, the web browser sends it to the DNS resolver. The resolver queries the root server, which directs it to the appropriate top-level domain server (e.g., .com). This server then directs to a second-level domain server, which finally provides the IP address. The resolver passes this IP to the browser, allowing it to connect to the web server and display the requested page. If the top-level domain is a country domain, the process is similar.