Internet Address ClassesClass A (/8 address)
The first digit is fixed, ranging 1-126 (01-7E), 16 million addresses
127.x.x.x is reserved for loopback
Class B (/16 address)
First two bytes are fixed with the first digit ranging 128-191 (80-BF), 65,000 addresses.
Class C (/24 address)
First 3 bytes are fixed, with the first digit ranging 192-223 (C0-DF), 254 addresses.
Class D & E
The first digit is 224-239 (E0-EF) and 240-255 (F0-FF) respectively.
Reserved for special purposes and not available to organizations.