Appendix Hip Subnetting; Chart H-1 Classes Of Ip Addresses - ZyXEL Communications VANTAGE RADIUS 50 User Manual

IP Addressing
Routers "route" based on the network number. The router that delivers the data packet to the
correct destination host uses the host ID.
IP Classes
An IP address is made up of four octets (eight bits), written in dotted decimal notation, for
example, 192.168.1.1. IP addresses are categorized into different classes. The class of an address
depends on the value of its first octet.
Class "A" addresses have a 0 in the left most bit. In a class "A" address the first octet is the network
number and the remaining three octets make up the host ID.
Class "B" addresses have a 1 in the left most bit and a 0 in the next left most bit. In a class
"B" address the first two octets make up the network number and the two remaining octets
make up the host ID.
Class "C" addresses begin (starting from the left) with 1 1 0. In a class "C" address the first
three octets make up the network number and the last octet is the host ID.
Class "D" addresses begin with 1 1 1 0. Class "D" addresses are used for multicasting. (There
is also a class "E" address. It is reserved for future use.)
IP ADDRESS:
Class A 0
Class B 10
Class C 110
Therefore:
IP Subnetting

Chart H-1 Classes of IP Addresses

OCTET 1
Network number
Network number
Network number
Host IDs of all zeros or all ones are not allowed.
OCTET 2
Host ID
Network number
Network number
Vantage RADIUS User's Guide
Appendix H
IP Subnetting
OCTET 3
Host ID
Host ID
Network number
OCTET 4
Host ID
Host ID
Host ID
H-1