What is subnetting and how do you calculate subnets?
Answer
Subnetting is the process of dividing a larger network into smaller, more manageable subnetworks. It improves security (contain broadcast traffic), performance, and IP address management. To subnet 192.168.1.0/24 into 4 subnets: borrow 2 bits from the host portion (2^2 = 4 subnets), giving /26 (26 network bits). Each subnet has 64 addresses (2^6), 62 usable hosts, and they are: 192.168.1.0/26 (hosts .1–.62, broadcast .63), 192.168.1.64/26 (hosts .65–.126, broadcast .127), 192.168.1.128/26, 192.168.1.192/26. Formula: number of subnets = 2^(borrowed bits); hosts per subnet = 2^(remaining host bits) - 2. VLSM (Variable Length Subnet Masking) allows different subnet sizes in the same network, reducing waste. For example, a point-to-point link needs only /30 (2 hosts) rather than a /24.