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IP Addressing Basics

IP Addressing Basics
The PIN Codes of Networking

In the Indian Postal System, every letter needs a PIN code and a house number to reach the right destination. Without these, the postman cannot deliver your parcel. Similarly, in networking, every device needs a unique address so data packets know exactly where to go.

Networking uses two types of addresses:

  • IP Address (logical) → like a postal PIN code.
  • MAC Address (physical) → like the unique house number.

Core Concepts

  • IP Address
    • A logical identifier assigned to each device.
    • IPv4: 32-bit, written as four numbers (e.g. 192.168.1.1).
    • IPv6: 128-bit, written in hexadecimal (e.g. 2001:db8::1).
    • Like a PIN code, it tells the network which area/device the packet should reach.
  • MAC Address
    • A physical identifier tied to the network interface card (NIC).
    • Example: 00:1A:2B:3C:4D:5E.
    • Like a house number, it uniquely identifies the device within the PIN code area.
  • Subnetting
    • Divides a large network into smaller sub-networks.
    • Like dividing a city into postal zones for efficient delivery.
    • Example: 192.168.1.0/24 → 256 addresses in one zone.
  • Public vs Private IPs
    • Public IP: Globally unique, like your official postal address.
    • Private IP: Local use only, like your society’s internal numbering system.
  • Static vs Dynamic IPs
    • Static IP: Fixed, like a permanent shop address.
    • Dynamic IP: Changes over time, like temporary stalls in a market.

Hands‑On Exercise

  1. Subnetting Practice
    Use an online subnet calculator to divide 192.168.1.0/24 into smaller subnets.
    Compare it to dividing a city into postal zones.

Check Public IP

curl ifconfig.me

Displays your public IP - the “official postal address” visible to the internet.

Check Your IP Address

ip addr show   # Linux
ipconfig       # Windows

Identify your device’s IP and MAC addresses.

Real‑World Relevance

  • Cloud Networking: AWS VPCs and Azure VNets use subnets like postal zones to organize resources.
  • Security: Firewalls often filter traffic based on IP ranges, just like postal checks at sorting centers.
  • Troubleshooting: Wrong IP addressing is like writing the wrong PIN code and then the packet never arrives.

The Hackers Notebook

IP addressing is the postal addressing system of networking. IPs act like PIN codes, MAC addresses like house numbers, and subnetting like dividing cities into zones. Without proper addressing, packets wander aimlessly, just like undeliverable letters in the postal system.

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Updated on Jan 3, 2026