D-Link DI-206 User Manual - Ip Network Classes

DI-206 ISDN Remote Router

Appendix B - IP Concepts

159

Networks attached to the Internet are assigned class types that determine the maximum

number of possible hosts per network. The previous figure illustrates how the net and host

portions of the IP address differ among the three classes. Class A is assigned to networks that

have more than 65,535 hosts; Class B is for networks that have 256 to 65534 hosts; Class C

is for networks with less than 256 hosts.

IP Network Classes

Class

Maximum

Number of

Networks in

Class

Network Addresses (Host

Portion in Parenthesis)

Maximum

Number of

Hosts per

Network

A

126

1(.0.0.0) to 126(.0.0.0)

16,777,214

B

16,382

128.1(.0.0) to 191.254(.0.0)

65,534

C

2,097,150

192.0.1(.0) to 223.255.254(.0)

254

Note:

All network addresses outside of these ranges (Class D and E) are either reserved or set

aside for experimental networks or multicasting.

When an IP address's host portion contains only zero(s), the address identifies a network and

not a host. No physical device may be given such an address.

The network portion must start with a value from 1 to 126 or from 128 to 223. Any other

value(s) in the network portion may be from 0 to 255, except that in class  B the network

addresses 128.0.0.0 and 191.255.0.0 are reserved, and in class C the network addresses

192.0.0.0 and 223.255.255.0 are reserved.