Which IP address class belongs to multicast?

 

Answer: Class D

An IPv4 address can be divided into five classes in classful IP addressing as follows:

• Class A
• Class B
• Class C
• Class D
• Class E

Class A: In 32 bits, the first 8 bits are for the network part, and the remaining 24 bits are reserved for the host part of the address. The leading first bit of the octet is fixed as ‘0’.

Network addresses: 2⁷−2 = 12627−2 = 126 usable addresses

Host addresses: 2²⁴−2 = 16,777,214224−2 = 16,777,214 usable addresses

Class B: In 32 bits, the first 16 bits are for the network part , and the remaining 16 bits are reserved for the host part of the address. The leading first two bits of the octet are fixed as ‘01’.

Network addresses: 2¹⁴ = 16384214 = 16384 usable addresses

Host addresses: 2¹⁶–2 = 65534216–2 = 65534 usable addresses

Class C: In 32 bits, the first 24 bits are for the network part , and the remaining 8 bits are reserved for the host part of the address. The leading first three bits of the octet are fixed as ‘110’.

Network addresses: 2²¹ = 2097152221 = 2097152 usable addresses

Host addresses: 2⁸–2 = 25428–2 = 254 usable addresses

Class D: Reserved for multicasting. Higher-order bits of the octet are set as ‘1110’.

Class E: Reserved for experiment and research purposes. Higher-order bits of the octet are set as ‘1111’.

The issue with IPv4 classful addressing is that thousands of addresses are wasted in Class A, few in Class B. Class C has few addresses which are not sufficient.

To overcome these issues Classless Inter-Domain Routing (CIDR) has taken the place of classful addressing.