Subnetting is the process of dividing a large network into smaller, more manageable segments called subnets. This is done by borrowing bits from the host portion of an IP address and assigning them to the network portion, effectively creating multiple smaller networks within a larger one.

• IP Address Example: 192.168.1.0/24
  This can be split into smaller subnets like 192.168.1.0/26, 192.168.1.64/26, etc.

Each subnet has:

• A network address (identifies the subnet)
• A range of usable IP addresses (for devices)
• A broadcast address (for sending data to all devices in the subnet)

Why is Subnetting Important?

1. Efficient IP Address Management:
   Subnetting helps avoid IP wastage. Instead of allocating a large block of IPs to a small network, you can assign just what’s needed.
2. Improved Network Performance:
   By reducing the size of broadcast domains, subnetting minimizes unnecessary traffic, improving speed and efficiency.
3. Enhanced Security:
   Subnets can isolate sensitive parts of a network, limiting access and reducing the risk of unauthorized intrusion.
4. Simplified Troubleshooting:
   Smaller networks are easier to monitor and manage, making it faster to detect and resolve issues.
5. Flexible Network Design:
   Subnetting allows for organized, scalable networks that can grow without major reconfiguration.

Real-World Example:

A company has the IP block 192.168.1.0/24 with 256 IP addresses.

• Without subnetting: All devices are in one large network, leading to heavy broadcast traffic.
• With subnetting: The company can create four subnets of 64 addresses each (/26), assigning different departments their own subnet. This improves performance, security, and manageability.