Internet Protocol Classes

IP Address Classes

The 5 Different Classes Of IP Address

Class A : 1.0.0.0 to 127.255.255.255
Class B : 128.0.0.0 to 191.255.255.255
Class C : 192.0.0.0 to 223.255.255.255
Class D : 224.0.0.0 to 239.255.255.255
Class E : 240.0.0.0 to 255.255.255.255

The following table shows the IP Addresses that you should avoid using:

IP Address	Function
Network 0.0.0.0	Refers to the default route. This route is to simplify routing tables used by IP.
Network 127.0.0.0	Reserved for Loopback. The Address 127.0.0.1 is often used to refer to the local host. Using this Address, applications can address a local host as if it were a remote host.
IP Address with all host bits set to "0" (Network Address) e.g 192.168.0.0	Refers to the actual network itself. For example, network 192.168.0.0 can be used to identify network 192.168. This type of notation is often used within routing tables.
IP Address with all node bits set to "1" (Subnet / Network Broadcast) e.g 192.168.255.255	IP Addresses with all node bits set to "1" are local network broadcast addresses and must NOT be used. Some examples: 125.255.255.255 (Class A) , 190.30.255.255 (Class B), 203.31.218.255 (Class C). See "Multicasts" & "Broadcasts" for more info.
IP Address with all bits set to "1" (Network Broadcast) e.g 255.255.255.255	The IP Address with all bits set to "1" is a broadcast address and must NOT be used. These are destined for all nodes on a network, no matter what IP Address they might have.