IANA (Internet Assigned Number Authority) assigned Internet Protocol Address to the vendors. Internet Protocol version four divided by five structure classes. The five structure classes are A, B, C, D, and E classes. What are the historical signification for classes A, B, and C? What are the address spaces for each class? What are RFC 1918 Internet Protocol address ranges and its special use?
The first three classes (A, B, C) are mainly for public use, and the last two classes (D and E) are for experimental and reserved for multicast. The first octet in the Internet Protocol Address determines its structure class. Class A addresses are ranges from one to one hundred and twenty-six in the first octet. Class B addresses are ranges from one hundred twenty-eight to one hundred and ninety-one in the first octet.
Class C addresses are ranges from one hundred and ninety-two to two hundred and twenty-three in the first octet. Class D addresses are ranges from two hundreds and twenty-four to two hundred and thirty-nine in the first octet. Finally, class D addresses are ranges from two hundred and forty to two hundred and fifty in the first octet.
Class A Internet Protocol addresses are reversed for a few large organizations. The network identifiers in class A are the remaining seven bits of the first octet. Class A addresses are available up to sixteen millions host addresses. Class B addresses are for medium sized enterprise. The first two octets (16 bits) in class B Internet Protocol addresses are for network addresses. The last two octets (16 bits) in class B are for the host addresses. Class B addresses has more than 65,000 networks. Class C Internet Protocol addresses are commonly found networks in the internet.
Class C Internet Protocol are private addresses. The first three octets (twenty-one bits) in class C addresses are for network addresses. The last octets (eight bits) in Class C address are for host identifiers. There are more than sixteen millions network addresses in Class C Internet Protocol. Class D Internet Protocol addresses are for multicasting and is not for general use. Class D addresses are not used for public.