Netmask tables 1)
Netmask CIDR Notes ===================================================================== 255.255.255.255 /32 Host (single address) 255.255.255.254 /31 Unusable 255.255.255.252 /30 4 IPs with 2 Usable 255.255.255.248 /29 8 IPs with 6 Usable 255.255.255.240 /28 16 IPs with 14 Usable 255.255.255.224 /27 32 IPs with 30 Usable 255.255.255.192 /26 64 IPs with 62 Usable 255.255.255.128 /25 128 IPs with 126 Usable 255.255.255.0 /24 256 IPs with 254 Usable "Class C"
Note: The first and last IP of a series are NOT usable and the first usable IP is normally set up for the router.
The 1st IP is the network address. The last IP is the broadcast address.
Subnetmask Translation Table
Subnetmask Subnetmask (binary) CIDR Notes
=================================================================================================
255.255.255.255 11111111.11111111.11111111.11111111 /32 Host (single address)
255.255.255.254 11111111.11111111.11111111.11111110 /31 Unusable
255.255.255.252 11111111.11111111.11111111.11111100 /30 4 IPs with 2 Usable
255.255.255.248 11111111.11111111.11111111.11111000 /29 8 IPs with 6 Usable
255.255.255.240 11111111.11111111.11111111.11110000 /28 16 IPs with 14 Usable
255.255.255.224 11111111.11111111.11111111.11100000 /27 32 IPs with 30 Usable
255.255.255.192 11111111.11111111.11111111.11000000 /26 64 IPs with 62 Usable
255.255.255.128 11111111.11111111.11111111.10000000 /25 128 IPs with 126 Usable
255.255.255.0 11111111.11111111.11111111.00000000 /24 256 IPs with 254 Usable
"Class C"
255.255.254.0 11111111.11111111.11111110.00000000 /23
255.255.252.0 11111111.11111111.11111100.00000000 /22
255.255.248.0 11111111.11111111.11111000.00000000 /21
255.255.240.0 11111111.11111111.11110000.00000000 /20
255.255.224.0 11111111.11111111.11100000.00000000 /19
255.255.192.0 11111111.11111111.11000000.00000000 /18
255.255.128.0 11111111.11111111.10000000.00000000 /17
255.255.0.0 11111111.11111111.00000000.00000000 /16
"Class B"
255.254.0.0 11111111.11111110.00000000.00000000 /15
255.252.0.0 11111111.11111100.00000000.00000000 /14
255.248.0.0 11111111.11111000.00000000.00000000 /13
255.240.0.0 11111111.11110000.00000000.00000000 /12
255.224.0.0 11111111.11100000.00000000.00000000 /11
255.192.0.0 11111111.11000000.00000000.00000000 /10
255.128.0.0 11111111.10000000.00000000.00000000 /9
255.0.0.0 11111111.00000000.00000000.00000000 /8
"Class A"
254.0.0.0 11111110.00000000.00000000.00000000 /7
252.0.0.0 11111100.00000000.00000000.00000000 /6
248.0.0.0 11111000.00000000.00000000.00000000 /5
240.0.0.0 11110000.00000000.00000000.00000000 /4
224.0.0.0 11100000.00000000.00000000.00000000 /3
192.0.0.0 11000000.00000000.00000000.00000000 /2
128.0.0.0 10000000.00000000.00000000.00000000 /1
0.0.0.0 00000000.00000000.00000000.00000000 /0
IP space
Note: The first and last IP of a series are NOT usable and the first usable IP is normally set up for the router. The 1st IP is the network address. The last IP is the broadcast address.