Rede IPv4

IP = 32bits

00000000 | 00000000 | 00000000 | 00000000 = Octetos.

0->255 | 0->255 | 0->255 | 0->255  = Endereços.

1-0 = 2
2-0 = 4
3-0 = 8
4-0 = 16
5-0 = 32
6-0 = 64
7-0 = 128
8-0 = 256 hosts, na rede se retira o 0 e o 255 ficando:

256-2=254 hosts.

Usando 7 bits:
 rede 25 bits                                        host 7 bits                                               
00000000 | 00000000 | 00000000 | 00000000 

1-0 = 2
2-0 = 4
3-0 = 8
4-0 = 16
5-0 = 32
6-0 = 64
7-0 = 128

128 hosts - 2 hosts (rede  e Broadcast ) = 126 hosts.

192.168.0.0 -> 192.168.0.127 (0 rede e 127 broadcast)

Mascara de Sub-rede:

BIANRIO = 00000000 | 00000000 | 00000000 | 00000000

DECIMAL = 256,128,64,32,16,8,4,2 | 256,128,64,32,16,8,4,2 | 256,128,64,32,16,8,4,2 | 256,128,64,32,16,8,4,2 |