IP Addressing

[!NOTE] This module explores the core principles of IP Addressing, deriving solutions from first principles and hardware constraints to build world-class, production-ready expertise.

1. What is an IP Address?

An Internet Protocol (IP) address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. It serves two main functions: Host identification and Location addressing.

2. IPv4 Structure (32-bits)

IPv4 addresses are 32 bits long, usually written in Dotted Decimal Notation. Example: 192.168.1.1

  • Binary: 11000000.10101000.00000001.00000001
  • Total unique addresses: 232 ≈ 4.3 billion.

3. Network vs. Host Portions

Every IP address consists of two parts:

  1. Network Portion: Identifies the specific network the device belongs to.
  2. Host Portion: Identifies the specific device on that network. The boundary between these two is defined by the Subnet Mask.

4. Interactive: Binary Converter

See how decimals turn into bits.

Input Decimal Octet (0-255)
128
64
32
16
8
4
2
1
11000000

5. Public vs. Private IPs

  • Public IP: Routable on the Global Internet. Must be unique worldwide.
  • Private IP: Used inside LANs (Home, Office). Not routable on the Internet.
  • 192.168.0.0 - 192.168.255.255
  • 10.0.0.0 - 10.255.255.255
  • 172.16.0.0 - 172.31.255.255

[!TIP] Loopback Address: 127.0.0.1 (localhost). Used for the computer to talk to itself.