Back to course

Introduction to IPv4 Addressing Fundamentals

CCNA: 0 to Hero - Comprehensive Network Engineering Bootcamp

Lesson 11: Introduction to IPv4 Addressing

IPv4 (Internet Protocol version 4) is the Layer 3 logical addressing system used for routing data across networks.

IPv4 Structure

  • IPv4 addresses are 32 bits long.
  • They are divided into four 8-bit sections called octets.
  • They are represented in dotted-decimal notation (e.g., 192.168.1.1).

Network vs. Host Portions

An IP address is logically divided into two parts:

  1. Network Portion: Identifies the specific network segment (must be the same for all devices on that segment).
  2. Host Portion: Uniquely identifies a specific device on that network.

The Subnet Mask

To determine which part of the address is the Network and which is the Host, we use the Subnet Mask. The mask works in conjunction with the IP address.

  • A 1 in the mask indicates the Network portion.
  • A 0 in the mask indicates the Host portion.

Example:

| IP Address: | 192.168.1.10 | | Mask: | 255.255.255.0 | | Binary (relevant part): | 11111111.11111111.11111111.00000000 |

The first three octets (24 bits) are the Network, and the last octet (8 bits) is the Host.