the subject of subnetting is very un clear to me, i mean if we have many network segments and suppose we use class B IP addresses why we not just make the first netork id 135.120.00 as an example and the second 135.121.00 or 188.8.131.52
with network mask 255.255.0.0 why we need to take from the 16 bits of the hosts to create subnets with masks such as 255.255.224.0 ??!!
in my example if you know the class of ip address you will know the network id and subnet mask without needing to chack bits of it so whats the reason of complicating it ??!!!!!!!!