Variable Length Subnet Mask (VLSM)

Variable Length Subnet Masking - VLSM -  is a technique that allows network administrators to divide an IP address space into subnets of different sizes, unlike simple same-size Subnetting.


 Variable Length Subnet Mask (VLSM) in a way, means subnetting a subnet. To simplify further, VLSM is the breaking down of IP addresses into subnets (multiple levels) and allocating it according to the individual need on a network. It can also be called a classless IP addressing. A classful addressing follows the general rule that has been proven to amount to IP address wastage.

	192.168.1.0/24
	50 Host
	30 Host
	10 Host
	2 Host
1 Step:	50 Host
	2^X-2=50
	X=6
	255.255.255.00111111	63
	192.168.1.1/26	32-6=26
	192.168.1.63/26
2 Step:	30 Host
	2^X-2=30
	X=5
	255.255.255.00011111	31	64+31=95
	192.168.1.64/27	32-5=27
	192.168.1.95/27
3 Step:	10 Host
	2^X-2=10
	X=4
	255.255.255.00001111	15	96+15=111
	192.168.1.96/28	32-4=28
	192.168.1.111/28
4 Step:	2 Host
	2^X-2=2
	X=2
	255.255.255.00000011	3
	192.168.1.112/30	32-2=30	112+3=115
	192.168.1.115/30