Subnetting
Subnetting divides a large network into smaller, more manageable segments. Each subnet operates as its own smaller network, improving performance and security.
Why Subnet?
- Reduces broadcast traffic within each network segment
- Improves security by isolating groups of hosts
- Allows more efficient use of IP address space
Subnet Masks
A subnet mask determines which portion of an IP address represents the network and which part identifies the host. Increasing the subnet mask bits creates more subnets with fewer hosts in each.
CIDR Notation
Classless Inter-Domain Routing (CIDR) expresses the network prefix after a slash. For example, 192.168.0.0/24 designates a network with 256 addresses, while 192.168.0.0/26 creates four smaller subnets with 64 addresses each.
Summary
Subnetting is a key technique for designing scalable networks. By adjusting the subnet mask, administrators control how traffic is isolated and how addresses are allocated.
Example
Consider the network 10.0.0.0/24. Splitting this into four /26 subnets yields:
10.0.0.0/2610.0.0.64/2610.0.0.128/2610.0.0.192/26
Each subnet supports up to 62 hosts. Planning subnets this way ensures growth while keeping broadcast domains small.