# HELP PLSSS

Inactive Imported Users Posts: 167
Guys,

I need your help regarding subnetting. Can you explain to me how come the maximum subnet you can create in class b is 254. Ok i know there is a reserved 2 bits when using subnetting.

Can you explain to me each class a,b,c the maximum and minimum subnet and the maximum and minumum number of host I can use.

I know how to get the broadcast, subnet and number of host, but when I got a question from some site that What is the maximum number of subnet you can create in class B. second question what is the minumum number of host you can create in class C when you borrowed 2 bits. (128,1920,0,0,0,0,0)

Thanks & regards,
Chinaman

• Member Posts: 101
With subnetting, an IP address can be divided into 3 portions. They are the Network portion, Subnet portion, and Host portion.

An Class A network has the leftmost 8 bits as the network portion, leaving the rightmost 24 bits for the subnet portion and host portion. Depending on the number of hosts you need for each subnet, and the number of subnets you need for the network, you can divide the 24 bits into the subnet portion and host portion based on the following formulas:

#subnet bits + #host bits = 24
#hosts per subnet = (2 ^ #host bits) – 2.
#subnets per network = 2 ^ #subnet bits (if subnet-zero is enabled)
#subnets per network = (2 ^ #subnet bits) - 2 (if subnet-zero is not enabled)

Similarly, for a Class B network, you have:
#subnet bits + #host bits = 16

For a Class C network, you have:
#subnet bits + #host bits = 8
KPLAB
www.kp-lab.com - Free CCNA, CCNP, and Network+ Study Guides
• Inactive Imported Users Posts: 167
Thanks for your clear explanation, but I want to know the maximum and the minimum range of subent and networks I can create or use. although it is not important and maybe it will not ask in the exam, I just want to know, so that it would clear for me.

Thanks again,
Chinaman
• Member Posts: 166
Max valid subnets for a class C address = ( (2 ^ 8 ) - 2) = 254
Max valid subnets for a class B address = ( (2 ^ 16) - 2) = 65534
Max valid subnets for a class A address = ( (2 ^ 24) - 2) = 16777214