CIDR(Classless Inter-Domain Routing) 표기법

CIDR(Classless Inter-Domain Routing) 표기법

CIDR표기법	허용 IP
192.0.0.0/8	192.0.0.0 ~ 192.255.255.255
192.168.0.0/16	192.168.0.0 ~192.168.255.255
192.168.67.0/24	192.168.67.0 ~ 192.168.67.255

'0/n'은 
IP주소에서 처음부터 n비트수 만큼이 네트워크 주소를 의미하고, 나머지 뒤의 비트들은 호스트 주소임을 의미합니다.

예를 들어
10.25.0.0/16 = 00001010 00011001 00000000 00000000

빨간색은 네트워크 주소, 파란색은 호스트 주소를 의미합니다. 

IP/CIDR	Δ to last IP addr	Mask	Hosts (*)	Class	Notes
a.b.c.d/32	+0.0.0.0	255.255.255.255	1	1/256 C
a.b.c.d/31	+0.0.0.1	255.255.255.254	2	1/128 C	d = 0 ... (2n) ... 254
a.b.c.d/30	+0.0.0.3	255.255.255.252	4	1/64 C	d = 0 ... (4n) ... 252
a.b.c.d/29	+0.0.0.7	255.255.255.248	8	1/32 C	d = 0 ... (8n) ... 248
a.b.c.d/28	+0.0.0.15	255.255.255.240	16	1/16 C	d = 0 ... (16n) ... 240
a.b.c.d/27	+0.0.0.31	255.255.255.224	32	1/8 C	d = 0 ... (32n) ... 224
a.b.c.d/26	+0.0.0.63	255.255.255.192	64	1/4 C	d = 0, 64, 128, 192
a.b.c.d/25	+0.0.0.127	255.255.255.128	128	1/2 C	d = 0, 128
a.b.c.0/24	+0.0.0.255	255.255.255.000	256	1 C
a.b.c.0/23	+0.0.1.255	255.255.254.000	512	2 C	c = 0 ... (2n) ... 254
a.b.c.0/22	+0.0.3.255	255.255.252.000	1,024	4 C	c = 0 ... (4n) ... 252
a.b.c.0/21	+0.0.7.255	255.255.248.000	2,048	8 C	c = 0 ... (8n) ... 248
a.b.c.0/20	+0.0.15.255	255.255.240.000	4,096	16 C	c = 0 ... (16n) ... 240
a.b.c.0/19	+0.0.31.255	255.255.224.000	8,192	32 C	c = 0 ... (32n) ... 224
a.b.c.0/18	+0.0.63.255	255.255.192.000	16,384	64 C	c = 0, 64, 128, 192
a.b.c.0/17	+0.0.127.255	255.255.128.000	32,768	128 C	c = 0, 128
a.b.0.0/16	+0.0.255.255	255.255.000.000	65,536	256 C = 1 B
a.b.0.0/15	+0.1.255.255	255.254.000.000	131,072	2 B	b = 0 ... (2n) ... 254
a.b.0.0/14	+0.3.255.255	255.252.000.000	262,144	4 B	b = 0 ... (4n) ... 252
a.b.0.0/13	+0.7.255.255	255.248.000.000	524,288	8 B	b = 0 ... (8n) ... 248
a.b.0.0/12	+0.15.255.255	255.240.000.000	1,048,576	16 B	b = 0 ... (16n) ... 240
a.b.0.0/11	+0.31.255.255	255.224.000.000	2,097,152	32 B	b = 0 ... (32n) ... 224
a.b.0.0/10	+0.63.255.255	255.192.000.000	4,194,304	64 B	b = 0, 64, 128, 192
a.b.0.0/9	+0.127.255.255	255.128.000.000	8,388,608	128 B	b = 0, 128
a.0.0.0/8	+0.255.255.255	255.000.000.000	16,777,216	256 B = 1 A
a.0.0.0/7	+1.255.255.255	254.000.000.000	33,554,432	2 A	a = 0 ... (2n) ... 254
a.0.0.0/6	+3.255.255.255	252.000.000.000	67,108,864	4 A	a = 0 ... (4n) ... 252
a.0.0.0/5	+7.255.255.255	248.000.000.000	134,217,728	8 A	a = 0 ... (8n) ... 248
a.0.0.0/4	+15.255.255.255	240.000.000.000	268,435,456	16 A	a = 0 ... (16n) ... 240
a.0.0.0/3	+31.255.255.255	224.000.000.000	536,870,912	32 A	a = 0 ... (32n) ... 224
a.0.0.0/2	+63.255.255.255	192.000.000.000	1,073,741,824	64 A	a = 0, 64, 128, 192
a.0.0.0/1	+127.255.255.255	128.000.000.000	2,147,483,648	128 A	a = 0, 128
0.0.0.0/0	+255.255.255.255	000.000.000.000	4,294,967,296	256 A

 

참고.
http://en.wikipedia.org/wiki/CIDR

출처: http://jjeong.tistory.com/396 [jjeong]