what is class A,B,C,D in ip address code example

Example: what is ip address class

Class	Leading bits	Size of network number bit field	Size of rest bit field	Number of networks	Addresses per network Total addresses in class	Start address	End address
Class A	    0	    8	    24	    128 (27)	    16,777,216 (224)	    2,147,483,648 (231)	0.0.0.0	127.255.255.255
Class B	    10	    16	    16	    16,384 (214)	    65,536 (216)	    1,073,741,824 (230)	128.0.0.0	191.255.255.255
Class C	    110	    24	    8	    2,097,152 (221)	    256 (28)	    536,870,912 (229)	192.0.0.0	223.255.255.255
Class D (multicast)	    1110	    not defined	    not defined	    not defined	    not defined	    268,435,456 (228)	224.0.0.0	239.255.255.255
Class E (res