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rfc1918 IP Address Space

Block Size IP Range # IP Addresses Blocks Network
24-bit block 10.0.0.0 – 10.255.255.255 16,777,215 single class A 10.0.0.0/8
20-bit block 172.16.0.0 – 172.31.255.255 1,048,576 16 contiguous class Bs 172.16.0.0/12
16-bit block 192.168.0.0 – 192.168.255.255 65,535 256 contiguous class Cs 192.168.0.0/16

Netmask Cheat Sheet

Netmask Reference
Mask Bits Number Hosts Usable
hosts
netmask Wildcard
/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 31 255.255.255.224 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

2 Responses to rfc1918 IP Space and Netmask Cheat Sheet

  • all that work done for us and you still forget 172.16? you must be getting old…

  • I did’nt remember it then either…. I just “faked” it… 😉

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