Netmasks From Hell
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Useable IPs IPs lost
Masks Dec Nets Per Network Per Network
1000 0000 = 128 2 126 4
1100 0000 = 192 4 62 8
1110 0000 = 224 8 30 16
1111 0000 = 240 16 14 32
1111 1000 = 248 32 6 64
1111 1100 = 252 64 2 128
1111 1110 = 254 128 - -
1111 1111 = 255 - - -
Classless masks
# Bit Mask Dotted-Decimal # of IP's Inverse
0 0000-0000.0000-0000.0000-0000.0000-0000 0.0.0.0 4,294,967,296 255.255.255.255
1 1000-0000.0000-0000.0000-0000.0000-0000 128.0.0.0 2,147,483,648 127.255.255.255
2 1100-0000.0000-0000.0000-0000.0000-0000 192.0.0.0 1,073,741,824 63.255.255.255
3 1110-0000.0000-0000.0000-0000.0000-0000 224.0.0.0 536,870,912 31.255.255.255
4 1111-0000.0000-0000.0000-0000.0000-0000 240.0.0.0 268,435,456 15.255.255.255
5 1111-1000.0000-0000.0000-0000.0000-0000 248.0.0.0 134,217,728 7.255.255.255
6 1111-1100.0000-0000.0000-0000.0000-0000 252.0.0.0 67,108,864 3.255.255.255
7 1111-1110.0000-0000.0000-0000.0000-0000 254.0.0.0 33,554,432 1.255.255.255
8 1111-1111.0000-0000.0000-0000.0000-0000 255.0.0.0 16,777,216 0.255.255.255
9 1111-1111.1000-0000.0000-0000.0000-0000 255.128.0.0 8,388,608 0.127.255.255
10 1111-1111.1100-0000.0000-0000.0000-0000 255.192.0.0 4,194,304 0.63.255.255
11 1111-1111.1110-0000.0000-0000.0000-0000 255.224.0.0 2,097,152 0.31.255.255
12 1111-1111.1111-0000.0000-0000.0000-0000 255.240.0.0 1,048,576 0.15.255.255
13 1111-1111.1111-1000.0000-0000.0000-0000 255.248.0.0 524,288 0.7.255.255
14 1111-1111.1111-1100.0000-0000.0000-0000 255.252.0.0 262,144 0.3.255.255
15 1111-1111.1111-1110.0000-0000.0000-0000 255.254.0.0 131,072 0.1.255.255
16 1111-1111.1111-1111.0000-0000.0000-0000 255.255.0.0 65,536 0.0.255.255
17 1111-1111.1111-1111.1000-0000.0000-0000 255.255.128.0 32,768 0.0.127.255
18 1111-1111.1111-1111.1100-0000.0000-0000 255.255.192.0 16,384 0.0.63.255
19 1111-1111.1111-1111.1110-0000.0000-0000 255.255.224.0 8,192 0.0.31.255
20 1111-1111.1111-1111.1111-0000.0000-0000 255.255.240.0 4,096 0.0.15.255
21 1111-1111.1111-1111.1111-1000.0000-0000 255.255.248.0 2,048 0.0.7.255
22 1111-1111.1111-1111.1111-1100.0000-0000 255.255.252.0 1,024 0.0.3.255
23 1111-1111.1111-1111.1111-1110.0000-0000 255.255.254.0 512 0.0.1.255
24 1111-1111.1111-1111.1111-1111.0000-0000 255.255.255.0 256 0.0.0.255
25 1111-1111.1111-1111.1111-1111.1000-0000 255.255.255.128 128 0.0.0.127
26 1111-1111.1111-1111.1111-1111.1100-0000 255.255.255.192 64 0.0.0.63
27 1111-1111.1111-1111.1111-1111.1110-0000 255.255.255.224 32 0.0.0.31
28 1111-1111.1111-1111.1111-1111.1111-0000 255.255.255.240 16 0.0.0.15
29 1111-1111.1111-1111.1111-1111.1111-1000 255.255.255.248 8 0.0.0.7
30 1111-1111.1111-1111.1111-1111.1111-1100 255.255.255.252 4 0.0.0.3
31 1111-1111.1111-1111.1111-1111.1111-1110 255.255.255.254 2 0.0.0.1
32 1111-1111.1111-1111.1111-1111.1111-1111 255.255.255.255 0 0.0.0.0
1000-0000 128
0100-0000 64
0010-0000 32
0001-0000 16
0000-1000 8
0000-0100 4
0000-0010 2
0000-0001 1
Classfull Nets
A 0 0.0.0.0 - 127.255.255.255
B 10 128.0.0.0 - 191.255.255.255
C 110 192.0.0.0 - 223.255.255.255
D 1110 224.0.0.0 - 239.255.255.255
E 11110 240.0.0.0 - 255.255.255.255
None routable networks
10.0.0.0/8 255.0.0.0
172.16.0.0/12 255.240.0.0
192.168.0.0/16 255.255.0.0
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