User Manual

31
Checking Valid IP Addresses
There are restrictions on which IP and 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:
¾ 127.x.x.x – this is a loop back address, used for testing
¾ 0.0.0.0 – this IP address represent the host address
¾ 255.255.255.255 – this is local broadcast address
¾ 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.
¾ 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
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.
Note: X denote don’t cares in the above example.