Subnet Masks and Subnets

Subnet Masks and Subnets:

notation		resulting subnet
netmask	shorthand	number of addresses
255.255.255.0	/24 [8-bit]	28 =	256	= 254 hosts + 1 bcast + 1 net base
255.255.255.128	/25 [7-bit]	27 =	128	= 126 hosts + 1 bcast + 1 net base
255.255.255.192	/26 [6-bit]	26 =	64	= 62 hosts + 1 bcast + 1 net base
255.255.255.224	/27 [5-bit]	25 =	32	= 30 hosts + 1 bcast + 1 net base
255.255.255.240	/28 [4-bit]	24 =	16	= 14 hosts + 1 bcast + 1 net base
255.255.255.248	/29 [3-bit]	23 =	8	= 6 hosts + 1 bcast + 1 net base
255.255.255.252	/30 [2-bit]	22 =	4	= 2 hosts + 1 bcast + 1 net base
255.255.255.254	/31 [1-bit]	21 =	–	Invalid (no possible hosts)
255.255.255.255	/32 [0-bit]	20 =	1	Host Route