HP J7949E manual IP Address Structure and Class, Table A.1 IP Address Class Format, Network Host

IP Address Structure and Class

An IP address is comprised of 32 bits of information and divided into 4 sections containing 1 byte each section or 4 bytes total:

xxx.xxx.xxx.xxx

For efficiency in routing, networks were broken down into three classes, so routing can begin simply by identifying the leading byte of information in the IP address. The three IP addresses that InterNIC assigns are class A, B, and C. The network class determines what each of the four IP address sections identify as shown in Table A.1:

Table A.1 IP Address Class Format

Class	First Address	Second	Third Address	Fourth
	Byte xxx.	Address	Byte xxx.	Address
		Byte xxx.		Byte xxx
A	Network.	Host.	Host.	Host
B	Network.	Network.	Host.	Host
C	Network.	Network.	Network.	Host

As illustrated in Table A.2, each network class differs by the leading bit identifier, the address range, the number of each type available, and the maximum number of hosts each class allows.

Table A.2 Network Class Characteristics

Class	Leading	Address Range	Maximum	Maximum
	Bit		Number of	Hosts in the
	Identifier		Networks in the	Network
			Class
A	0	0.0.0.0 to	126	Over 16 Million
		127.255.255.255
B	10	128.0.0.0 to	16,382	65,534
		191.255.255.255
C	110	192.0.0.0 to	Over 2 Million	254
		223.255.255.255

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