IP Adress & Domain Name & DNS

IP Address

• Definition: An IP (Internet Protocol) address is a unique numerical identifier for a device on a network.
• Types:
  • IPv4: 32‑bit, written as four numbers (e.g., 192.168.1.1).
  • IPv6: 128‑bit, written in hexadecimal (e.g., 2001:0db8:85a3::8a2e:0370:7334).
• Role: Machines use IP addresses to locate and communicate with each other.
• Problem: Numbers are hard for humans to remember.

Domain Name

• Definition: A domain name is a human‑friendly label that maps to an IP address.
• Examples:
  • google.com → maps to an IP like 142.250.190.14.
  • microsoft.com → maps to an IP like 20.81.111.85.
• Structure:
  • Top‑Level Domain (TLD): .com, .org, .net, .cn, etc.
  • Second‑Level Domain: google, microsoft.
  • Subdomain: mail.google.com, docs.microsoft.com.
• Role: Makes the Internet easier to use by replacing numbers with names.

DNS (Domain Name System)

• Definition: DNS is the “phonebook of the Internet”, translating domain names into IP addresses.
• How it works:
  • You type www.example.com in your browser.
  • Your computer asks a DNS resolver for the IP.
  • The resolver queries DNS servers (root → TLD → authoritative).
  • The IP address is returned (e.g., 93.184.216.34).
  • Your browser connects to that IP.
• Key Components:
  • Root servers: Handle top‑level domains.
  • TLD servers: Handle .com, .org, etc.
  • Authoritative servers: Store actual domain‑to‑IP mappings.
• Caching: DNS results are cached locally and by ISPs to speed up lookups.

Relationship Between Them

• IP: The actual numeric address of a device.
• Domain: A human‑readable name pointing to that IP.
• DNS: The system that translates between the two.

Example:

• You type www.microsoft.com.
• DNS finds its IP (e.g., 20.81.111.85).
• Your browser connects to that IP, and the website loads.

Summary

• IP = numeric identifier.
• Domain = human‑friendly name.
• DNS = translator between domain and IP. Together, they make the Internet usable for both machines and humans.