Here’s a simple chart that explains the various IP classes and the difference between /32, /24, /16
77.217.66.0/32 = 77.217.66.0 through 77.217.66.0 [1 IP - Single IP]
77.217.66.0/31 = 77.217.66.0 through 77.217.66.1 [2 IPs]
77.217.66.0/30 = 77.217.66.0 through 77.217.66.3 [4 IPs]
77.217.66.0/29 = 77.217.66.0 through 77.217.66.7 [8 IPs]
77.217.66.0/28 = 77.217.66.0 through 77.217.66.15 [16 IPs]
77.217.66.0/27 = 77.217.66.0 through 77.217.66.31 [32 IPs]
77.217.66.0/26 = 77.217.66.0 through 77.217.66.63 [64 IPs]
77.217.66.0/25 = 77.217.66.0 through 77.217.66.127 [128 IPs]
77.217.66.0/24 = 77.217.66.0 through 77.217.66.255 [256 IPs - Class C]
77.217.0.0/16 = 77.217.0.0 through 77.217.255.255 [65536 IPs - Class B]