NET:Network address segment

A:1.0.0.1~126.255.255.254   (00000001 00000000 00000000 00000001~01111110 11111111 11111111 11111110)
mask:255.0.0.0
hostnumbers:256^3-2=16777214

B:128.1.0.1~191.254.255.254 (10000000 00000001 00000000 00000001~10111111 11111110 11111111 11111110)
mask:255.255.0.0
hostnumbers:256^2-2=65534

C.192.0.1.1-223.255.254.254 (11000000 00000000 00000001 00000001~11011111 11111111 11111110 11111110)
mask:255.255.255.0
hostnumbers:256-2=254


private net address
A: 10.0.0.0
B: 172.16.0.0~172.32.0.0
C: 192.168.0.0

10/8           : 10.0.0.0～10.255.255.255
172.16/12  : 172.16.0.0～172.31.255.255
192.168/16: 192.168.0.0～192.168.255.255