Subnetting

Subnet Masks

Class	IP Range	Binary IP Range
A	255.0.0.0	11111111.00000000.00000000.00000000
B	255.255.0.0	11111111.11111111.00000000.00000000
C	255.255.255.0	11111111.11111111.11111111.00000000
Ones (1's) are network bits. Zeros (0's) are node bits (assignable address bits).

Max. Hosts (Per Class)

Class	Valid Addresses
A	16,777,216 (2^24)
B	65,536 (2^16)
C	256 (2^8)

Classless Inter Domain Routing (CIDR) Table

Bits	Subnet Mask	Subnets	Hosts
8	255.0.0.0	1	16,777,216
16	255.255.0.0	256	65,534
24	255.255.255.0	65,536	254
25	255.255.255.128	131,072	126
26	255.255.255.192	262,144	62
27	255.255.255.224	524,288	30
28	255.255.255.240	1,048,576	14
29	255.255.255.248	2,097,152	6
30	255.255.255.252	4,194,304	2

Binary Subnet Representation

Decimal	Binary	Bits
.128	10000000	1
.192	11000000	2
.224	11100000	3
.240	11110000	4
.248	11111000	5
.252	11111100	6
.254	11111110	7
.255	11111111	8