Network Addressing

For several years IPv4 has been the standard method for assigning a unique address that identifies the host on the network and the Internet. The 32-bit IP address, also referred to as a dotted quad, is composed of four 8-bit fields divided by a period. These fields identify first the network and then the host for a device on the network. IPv4 provides 4.29 billion addresses.

The IP address 192.168.1.150 and the binary equivalent would be:

  • 11000000 10101000 00000001 10010110

IPv4 addresses are categorized into classes to provide structure. There are five classifications of networks defined by IP addresses. Table 19-1 identifies the address ranges for the classes that are primarily used.

Table 19-1. IPv4 address ranges by class

Address class

IP address range

Class A

0.0.0.0 to 127.255.255.255

Class B

128.0.0.0 to 191.255.255.255

Class C

192.0.0.0 to 223.255.255.255

Class D

224.0.0.0 to 239.255.255.255

Class E

240.0.0.0 to 247.255.255.255

Every device on a network or connected to the Internet needs a unique IP address, including printers and fax machines; consequently, the supply of available IP addresses will run out eventually. There have been many technologies developed to reduce the exhaustion of available IP addresses, including network address translation (NAT), Classless Inter-Domain Routing (CIDR), and IPv6.

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