Subnetting

Subnetting is a networking technique used to divide a larger network into smaller, more manageable subnetworks (subnets). It helps with better organization, efficient IP address allocation, and improved performance and security.

1. Purpose:

• Organization: Groups devices logically based on function or location for easier administration.
• Efficiency: Reduces broadcast domains, improving network performance.
• Security: Isolates subnets to limit security breaches and control resource access.
• IP Address Management: Prevents IP wastage and enables efficient address usage.

2. How It Works:

• Subnet Mask: Determines which part of the IP address is for the network and which is for the host.
• Borrowing Bits: Bits from the host portion are borrowed to create more subnets.
• Binary Representation: Subnetting relies on binary math to distinguish the network and host portions.
• Example: In a Class C network (255.255.255.0), borrowing 2 bits changes the subnet mask to 255.255.255.192. This results in 4 subnets with 62 usable host addresses each.

3. Benefits:

• Reduced Broadcast Traffic: Limits broadcast traffic to a subnet, improving efficiency.
• Enhanced Security: Helps contain threats within subnets.
• Simplified Management: Easier to organize, monitor, and troubleshoot network segments.
• Efficient IP Address Usage: Prevents IP waste, especially in large-scale networks.

4. Key Terms:

• Subnet: A smaller, logical division of a larger network.
• Subnet Mask: A 32-bit number indicating the network and host parts of an IP address.
• CIDR (Classless Inter-Domain Routing): A shorthand way to denote subnet masks, e.g., /24.
• Network ID: The first address in a subnet, identifying the subnet itself.
• Broadcast ID: The last address in a subnet, used for broadcasting to all devices within the subnet.
• First Host ID: The first usable IP address in a subnet (after the Network ID).
• Last Host ID: The last usable IP address before the Broadcast ID.