User manual
B-12 Addressing Scheme
s
IP Subnet Mask Address Table
Subnet masking is used to expand the number of networks due
to the 32-bit limitation of IP’s address field. When assigned an
address by the NIC, the address can be further broken down to
expand the single net number to many more by using host bits.
Sub-
net
Bits
Bit Positions Decimal Mask HEX
Mask
Sub-
Nets
Avail
.
Hosts
Avail.
Class A
0nnnnnnn.hhhhhhhh.hhhhhhhh.hhhhhhhh 7 FF-00-00-00 126 16777124
Class B
10nnnnnn.nnnnnnnn.hhhhhhhh.hhhhhhhh 255.255.0.0 FF-FF-00-00 16384 65534
2 10nnnnnn.nnnnnnnn.sshhhhhh.hhhhhhhh 255.255.192.0 FF-FF-C0-00 2 16382
3 10nnnnnn.nnnnnnnn.ssshhhhh.hhhhhhhh 255.255.224.0 FF-FF-E0-00 6 8190
4 10nnnnnn.nnnnnnnn.sssshhhh.hhhhhhhh 255.255.240.0 FF-FF-F0-00 14 4094
5 10nnnnnn.nnnnnnnn.ssssshhh.hhhhhhhh 255.255.248.0 FF-FF-F8-00 30 2046
6 10nnnnnn.nnnnnnnn.sssssshh.hhhhhhhh 255.255.252.0 FF-FF-FC-00 62 1022
7 10nnnnnn.nnnnnnnn.sssssssh.hhhhhhhh 255.255.254.0 FF-FF-FE-00 126 510
8 10nnnnnn.nnnnnnnn.ssssssss.hhhhhhhh 255.255.255.0 FF-FF-FF-00 254 154
9 10nnnnnn.nnnnnnnn.ssssssss.shhhhhhh 255.255.255.128 FF-FF-FF-80 510 126
10 10nnnnnn.nnnnnnnn.ssssssss.sshhhhhh 255.255.255.192 FF-FF-FF-C0 1022 62
11 10nnnnnn.nnnnnnnn.ssssssss.ssshhhhh 255.255.255.224 FF-FF-FF-E0 2046 30
12 10nnnnnn.nnnnnnnn.ssssssss.sssshhhh 255.255.255.240 FF-FF-FF-F0 4094 14
13 10nnnnnn.nnnnnnnn.ssssssss.ssssshhh 255.255.255.248 FF-FF-FF-F8 8190 6
14 10nnnnnn.nnnnnnnn.ssssssss.sssssshh 255.255.255.252 FF-FF-FF-FC 16382 2
Class C
110nnnnn.nnnnnnn.ssssssss.hhhhhhhh 255.255.255.0 FF-FF-FF-00
2097152
254
2 110nnnnn.nnnnnnnn.nnnnnnnn.sshhhhhh 255.255.255.192 FF-FF-FF-C0 2 62
3 110nnnnn.nnnnnnnn.nnnnnnnn.ssshhhhh 255.255.255.224 FF-FF-FF-E0 6 30
4 110nnnnn.nnnnnnnn.nnnnnnnn.sssshhhh 255.255.255.240 FF-FF-FF-F0 14 14
5 110nnnnn.nnnnnnnn.nnnnnnnn.ssssshhh 255.255.255.248 FF-FF-FF-F8 30 6
6 110nnnnn.nnnnnnnn.nnnnnnnn.sssssshh 255.255.255.252 FF-FF-FF-FC 62 2
Class D
1110xxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx
Future
11110xxx.xxxxxxxx.xxxxxxxx.xxxxxxxx
All 1s 11111111.11111111.11111111.11111111
All 0s 00000000.00000000.00000000.00000000
0 = binry 0 1 = binary 1 n = network bits h = host bits s = subnet bits x = other