Classes on the IP Address

Class A: Used for WAN networks, IP Address in the first part between 0-127, and the Net ID which is 1 part first.
Class B: Commonly used for MAN networks, IP Address in the first part between 128-191, and which is the Net ID which is the first 2 parts.
Class C: Usually used for LAN networks, IP Address in the first part between 192-223, and which is the Net ID which is the first 3 parts.
Class D: Usually used for multicasting purposes, the IP Address in the first part is between 224-247.
Class E: Usually used for public purposes, the IP Address in the first part is between 248-255.