DNS (Domain Name System)

Definition

DNS is a distributed naming system that translates a domain name (e.g., google.com) into an IP address (e.g., 142.250.190.78) so devices can locate and communicate with servers on a network or the internet.

What Problem It Solves

• Humans remember domain names, not IP addresses.
• Provides a name-to-IP mapping service.
• Allows websites to change server IPs without users needing to know.
• Supports services through DNS records (A, AAAA, CNAME, MX, TXT, etc.).

What Happens If Not Used

• Users would need to memorize and enter IP addresses.
• Websites, email, and many internet services would be difficult to access and manage.
• Server IP changes would break access unless everyone learned the new IP.

Easy Wording

DNS is the phonebook of the internet. You ask for a website name, and DNS tells your device which IP address to connect to.

Layman Example

You want to visit facebook.com.

• Browser asks DNS: "What is the IP of facebook.com?"
• DNS replies with the IP.
• Browser connects to that IP and loads the website.

Technical Example

User requests example.com.

• Browser checks cache.
• Queries a DNS Resolver.
• Resolver contacts Root Server → TLD Server (.com) → Authoritative DNS Server.
• Receives the required DNS Record (e.g., A Record).
• Returns the IP address.
• Browser connects to the web server.