/mask
/0 = the whole internet
/16 = a class 'B'
/24 = a class 'C' address
/32 = single host specified

192.168.0.0/32 is 192.168.0.0 (one host)
192.168.0.0/32 is 192.168.0.0 and 192.168.0.1 (two hosts)
192.168.0.0/28 is 192.168.0.0 through 192.168.0.15
192.168.0.0/24 is 192.168.0.0 through 192.168.0.255
192.168.0.0/22 is 192.168.0.0 through 192.168.0.255


The right-most octet in the subnet mask is always:
0, 128, 192, 224, 240, 248, 252, 254, or 255.