서브넷 마스크 계산표

1. Class별 Public IP Address의 범위
Class	Public IP의 범위 (Dec)	Public IP의 범위 (Bin)
A	1.xxx.xxx.xxx ~ 126.xxx.xxx.xxx	00000001.xxxxxxxx.xxxxxxxx.xxxxxxxx ~ 01111110.xxxxxxxx.xxxxxxxx.xxxxxxxx
B	128.1.xxx.xxx ~ 191.254.xxx.xxx	10000000.00000001.xxxxxxxx.xxxxxxxx ~ 10111111.11111110.xxxxxxxx.xxxxxxxx
C	192.0.1.xxx ~ 223.255.254.xxx	11000000.00000000.00000001.xxxxxxxx ~ 11011111.11111111.11111110.xxxxxxxx
2. Class별 Private IP Address의 범위
Class	Private IP의 범위
A	10.0.0.0 ~ 10.255.255.255	10.0.0.0/8	10.0.0.0                      255.0.0.0
B	172.16.0.0 ~ 172.31.255.255	172.16.0.0/12	172.16.0.0                 255.240.0.0
C	192.168.0.0 ~ 192.168.255.255	192.168.0.0/16	192.168.0.0               255.255.0.0
3. Subnet Mask 표
Subnet	Subnet Mask (Dec)	Host 수	비고
/8	255.0.0.0	16,777,216	A Class Default Subnet Mask
/9	255.128.0.0	8,388,608	A Class Subnet Mask
/10	255.192.0.0	4,194,304
/11	255.224.0.0	2,097,152
/12	255.240.0.0	1,048,576
/13	255.248.0.0	524,288
/14	255.252.0.0	262,144
/15	255.254.0.0	131,072
/16	255.255.0.0	65,536	B Class Default Subnet Mask
/17	255.255.128.0	32,768	B Class Subnet Mask
/18	255.255.192.0	16,384
/19	255.255.224.0	8,192
/20	255.255.240.0	4,096
/21	255.255.248.0	2,048
/22	255.255.252.0	1,024
/23	255.255.254.0	512
/24	255.255.255.0	256	C Class Default Subnet Mask
/25	255.255.255.128	128	C Class Subnet Mask
/26	255.255.255.192	64
/27	255.255.255.224	32
/28	255.255.255.240	16
/29	255.255.255.248	8
/30	255.255.255.252	4
/31	255.255.255.254	2
/32	255.255.255.255	1