IPv4 Network Classes and Related Facts

IP version 4 (IPv4) defines five address classes. Three of the classes, Classes A, B, and C, consist of unicast IP addresses. Unicast addresses identify a single host or interface so that the address uniquely identifies the device. Class D addresses serve as multicast addresses, so that one packet sent to a Class D multicast IPv4 address can actually be delivered to multiple hosts. Finally, Class E addresses are experimental.

The class can be identified based on the value of the first octet of the address, as shown in Table 14-2.

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Table 14-2 IPv4 Address Classes Based on First Octet Values

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