User manual

Checking Valid IP Addresses

There are restrictions on which IP addresses you can and cannot use. Some IP

addresses are reserved for testing, multicasting and some IP are restricted by your

ISP.

Following IP addresses cannot be used:

• 127.X.X.X – this is a loop back address, used for testing

• 0.0.0.0 – this IP address represent the host address.

• 255.255.255.255 – this is local broadcast address

• First portion of IP cannot exceed 224, that is, IP addresses which is in the

range of 224~239.X.X.X is not valid. This range of IP is for multicasting. IP

range from 240~255.X.X.X are reserved IP addresses and cannot be used.

• 0 or 255 in host ID portion of your IP are not valid. This represent local

host or broadcast address for your class of IP (explained in the next

paragraph).

IP has five classes, namely class A, B, C, D and E. For each class, the host ID

portion in the IP field is different for each of the classes. Figure below illustrate

this.

Class A: 1~127 . Host ID

Class B: 128~191 . X . Host ID

Class C: 192~223 . X . X . Host ID

Class D: 224~239

. Used for Multicasting (no Host ID)

Class E: 240~255 . Reserved IP address

Host ID cannot be all 0’s or all 255’s. For example, the following are not valid IP’s:

1~127.0.0.0 – invalid class A address

1~127.255.255.255 – invalid class A address

128~191.X.0.0 – invalid class B address

128~191.X.255.255 – invalid class B address

192~223.X.X.0 – invalid class C address

192~223.X.X.255 – invalid class C address

Note: X denote don’t cares in the above example