IP address structure and class

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:


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 below:

IP address class format
Class First Address Byte xxx. Second Address Byte xxx. Third Address Byte xxx. Fourth Address Byte xxx
A Network. Host. Host. Host.
B Network. Network. Host. Host.
C Network. Network. Network. Host.

As illustrated in IP address structure and class, 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.

Network class characteristics
Class Network Class Characteristics Address Range Maximum Number of Networks in the Class Maximum Hosts in the Network
A 0 to 126. Over 16 Million.
B 10. to 16,382. 65,534.
C 110. to Over 2 Million. 254.
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