Pembagian kelas alamat IPV4 : Id Jaringan (Network Id) dan Id Host (Host Id)
Kelas Alamat Jaringan (dalam biner):
Class A : 0xxxxxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx : SM = 255.0.0.0 256^3 host
0xxxxxxx = 00000000 – 01111111 = 0 - 127
Class B : 10xxxxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx: SM = 255.255.0.0  256^2 host
10xxxxxx = 10000000 – 10111111 = 128 - 191
Class C : 110xxxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx: SM = 255.255.255.0  256 host
110xxxxx = 11000000 – 11011111 = 192 - 223
Class D : 1110xxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx
1110xxxx = 11100000 – 11101111 = 224 - 239
Class E : 11110xxx.xxxxxxxx.xxxxxxxx.xxxxxxxx
SM = Subnet Mask
Setiap alamat dikurangi 2, satu untuk broadcasting, dan satu untuk jaringan
Dalam decimal :
Class A : 0.0.0.0 s/d 127.255.255.255 ( dikurangi 0.0.0.0 dan 127.255.255.255
)
Class B : 128.0.0.0 s/d 191.255.255.255 (
Class C : 192.0.0.0 s/d 223.255.255.255
Class D : 224.0.0.0 s/d 239.255.255.255
Class E : 240.0.0.0 s/d 247.255.255.255
Dalam biner:
Class A : 00000000.0000000.0000000.0000000 s/d 01111111.11111111.11111111.11111111
Class B : 10000000.0000000.0000000.0000000 s/d 10111111.11111111.11111111.11111111
Class C : 11000000.0000000.0000000.0000000 s/d 11011111.11111111.11111111.11111111
Class D : 224.0.0.0 s/d 239.255.255.255
Class E : 240.0.0.0 s/d 247.255.255.255
Alamat IP : Privat
Private IP Address untuk Class A: 10.0.0.0 s/d 10.255.255.255 = 256^3
Private IP Address untuk Class B: 172.16.0.0 s/d 172.31.255.255 = 256^2
Private IP Address untuk Class C: 192.168.0.0 s/d 192.168.255.255 = 256
NAT = Network Address Translator
192.168.0.1 di 200.200.200.0 memanggil 192.168.0.1 di 201.201.201.200 = routing