CIDR Notation	Net mask	# Host addresses
32	255.255.255.255	1
31	255.255.255.254	2
30	255.255.255.252	4
29	255.255.255.248	8
28	255.255.255.240	16
27	255.255.255.224	32
26	255.255.255.192	64
25	255.255.255.128	128
24	255.255.255.0	256

CIDR Notation	Net mask	# Class C Networks
24	255.255.255.0	1
23	255.255.254.0	2
22	255.255.252.0	4
21	255.255.248.0	8
20	255.255.240.0	16
19	255.255.224.0	32
18	255.255.192.0	64
17	255.255.128.0	128
16	255.255.0.0	256

CIDR Notation	Net mask	# Class B Networks
16	255.255.0.0	1
15	255.254.0.0	2
14	255.252.0.0	4
13	255.248.0.0	8
12	255.240.0.0	16
11	255.224.0.0	32
10	255.192.0.0	64
9	255.128.0.0	128
8	255.0.0.0	256

CIDR Notation	Net mask	# Class A Networks
8	255.0.0.0	1
7	254.0.0.0	2
6	252.0.0.0	4
5	248.0.0.0	8
4	240.0.0.0	16
3	224.0.0.0	32
2	192.0.0.0	64
1	128.0.0.0	128
0	0.0.0.0	256