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

Summary

This video provides an in-depth explanation of the Domain Name System (DNS), focusing on its purpose, components, and how it works. It covers key concepts such as domain names, DNS resolvers, name servers, and the hierarchical DNS structure. The video also explains two methods for resolving domain names—recursive and iterative—and provides real-life examples to illustrate how DNS queries are processed. By the end, viewers will have a clear understanding of how DNS enables smooth internet browsing by mapping domain names to IP addresses and vice versa.

Takeaways

• 😀 DNS (Domain Name System) is a critical system that translates human-readable domain names (e.g., www.example.com) into machine-readable IP addresses.
• 😀 The primary purpose of DNS is to simplify access to websites by mapping domain names to IP addresses, so users don't need to remember numeric addresses.
• 😀 DNS operates using a hierarchical structure with three main domain types: generic domains (e.g., .com), country-specific domains (e.g., .in), and inverse domains.
• 😀 DNS servers handle the mapping of domain names to IP addresses, and they use either **recursive** or **iterative** methods for resolving queries.
• 😀 In the **recursive method**, a DNS resolver queries multiple DNS servers on behalf of the user, seeking the correct address from root to TLD to second-level domain.
• 😀 In the **iterative method**, the DNS resolver queries each DNS server in sequence, with the user responsible for sending the request to the next server if necessary.
• 😀 DNS uses a **root server** to direct queries to the appropriate **top-level domain (TLD)** and then to the second-level domain (e.g., example.com).
• 😀 A DNS query involves sending a request from the user's browser to the DNS resolver, which then communicates with various DNS servers to resolve the domain name.
• 😀 **UDP (User Datagram Protocol)** is commonly used by DNS for faster query resolution, as it is quicker than the more complex TCP (Transmission Control Protocol).
• 😀 DNS enables seamless access to websites by converting user-friendly URLs into IP addresses, ensuring smooth navigation across the internet.

Q & A

What is DNS and why is it important?

DNS (Domain Name System) is a directory of the internet that maps domain names to IP addresses. It helps users access websites by resolving human-readable domain names (e.g., www.example.com) into IP addresses that computers use to identify each other on the network. This system allows us to use easy-to-remember names instead of difficult-to-memorize IP addresses.

What is the purpose of DNS?

The purpose of DNS is to map IP addresses to domain names and vice versa. It allows users to access websites using names rather than numeric IP addresses, which are harder for humans to remember. Essentially, DNS acts as an internet directory, making browsing easier.

Why does DNS use UDP instead of TCP by default?

DNS uses UDP (User Datagram Protocol) by default because it provides faster communication with lower latency compared to TCP (Transmission Control Protocol). Since DNS typically requires a quick response to resolve domain names, UDP is preferred due to its reduced overhead.

What are the main components of DNS?

The main components of DNS are: Domain Name, Namespace, Name Server, and Name Resolver. These components work together to resolve domain names into IP addresses and facilitate the browsing of websites.

What are the three types of domain names in DNS?

The three types of domain names in DNS are: Generic Domains (e.g., .com, .edu), Country Domains (e.g., .in for India, .au for Australia), and Inverse Domains, which are used to map IP addresses to domain names.

Can you explain the concept of a root server in DNS?

The root server is the highest level of the DNS hierarchy. It holds the complete database of domain names and their corresponding IP addresses, directing queries to the appropriate top-level domain (TLD) servers. It’s essential for locating specific domain names on the internet.

What is the difference between a primary server and a secondary server in DNS?

A primary server is responsible for maintaining and updating the DNS records for a domain. It holds the original copies of zone files. A secondary server, on the other hand, gets its information from the primary server and provides redundancy to ensure reliable DNS resolution.

What is a name resolver in DNS?

A name resolver is client-side software that helps map a domain name to its corresponding IP address (or vice versa). There are two types: recursive resolvers, which handle the entire lookup process, and iterative resolvers, which make the client handle part of the query process.

What is the difference between recursive and iterative DNS query methods?

In recursive DNS queries, the resolver (client software) asks the DNS server to fully resolve the query, and the server replies with the final result. In iterative queries, the resolver asks for a partial resolution and then continues querying other servers for further information, which places more burden on the client.

How does DNS work when a user wants to visit a website?

When a user wants to visit a website, their browser sends the domain name to a DNS resolver. The resolver sends the query to the root server, which directs it to the appropriate top-level domain server (e.g., .com). The process continues until the resolver reaches the correct server, which provides the IP address that the user's browser uses to connect to the website.