3Com AccessBuilder 500 User Manual - Ip Addresses

Routing IP and IPX

A-13

IP Addresses

TCP/IP Numbering and subnet masking IP numbers or 

addresses

 are 

normally made up of four fields (normally called 

bytes

), with each byte 

having a whole number value of between 0 and 255, and the bytes 

separated by a full stop. For example:

123.123.123.123

An IP address is divided into two sections, one is the 

Network Address 

section and the other is the 

Host

Address

 section. For example:

123.123.|123.123

Network Host 

The divider | between the two sections is moveable according to what 

class

 of IP address it is. The class of address is defined by what the 

number is in the first address byte:

■

For a Class A IP address the number in the first byte will be in the range 

00 to 126 

■

For a Class B IP address the numbers in the first & second bytes will be 

in the range 128.001 to 191.254

■

For a Class C IP address the numbers in the first, second & third bytes 

will be in the range 192.000.001 to 223.255.254 

For example:

Class A

1.|123.123.123

Network Host 

Class B

128.001.|123.123

Network Host 

Class C

192.123.123.|123

Network Host