IP

Netmask

# bits	# hosts	Usable hosts	netmask	Remark	Cisco mask
/4	268435456	268435454	240.0.0.0		15.255.255.255
/5	134217728	134217726	248.0.0.0		7.255.255.255
/6	67108864	67108862	252.0.0.0		3.255.255.255
/7	33554432	33554430	254.0.0.0		1.255.255.255
/8	16777216	16777214	255.0.0.0	class A network	0.255.255.255
/9	8388608	8388606	255.128.0.0		0.127.255.255
/10	4194304	4194302	255.192.0.0		0.63.255.255
/11	2097152	2097150	255.224.0.0		0.31.255.255
/12	1048576	1048574	255.240.0.0		0.15.255.255
/13	524288	524286	255.248.0.0		0.7.255.255
/14	262144	262142	255.252.0.0		0.3.255.255
/15	131072	131070	255.254.0.0		0.1.255.255
/16	65536	65534	255.255.0.0	class B network	0.0.255.255
/17	32768	32766	255.255.128.0		0.0.127.255
/18	16384	16382	255.255.192.0		0.0.63.255
/19	8192	8190	255.255.224.0		0.0.31.255
/20	4096	4094	255.255.240.0		0.0.15.255
/21	2048	2046	255.255.248.0		0.0.7.255
/22	1024	1022	255.255.252.0		0.0.3.255
/23	512	510	255.255.254.0		0.0.1.255
/24	256	254	255.255.255.0	class C network	0.0.0.255
/25	128	126	255.255.255.128		0.0.0.127
/26	64	62	255.255.255.192		0.0.0.63
/27	32	30	255.255.255.224		0.0.0.31
/28	16	14	255.255.255.240		0.0.0.15
/29	8	6	255.255.255.248		0.0.0.7
/30	4	2	255.255.255.252		0.0.0.3
/31				point to point links only
/32	1	1	255.255.255.255	single IP address	use host notation