Subnetting

Christopher Dobkowski

Hi guyz, I have a question about subnetting and I got the result but the result they gave me was wrong..

I answered 2 subnets and 126 users per subnet... After revealing the answer they said its 512 subnets and 126 hosts... how's that possible?!

How many subnets and hosts per subnet can you get from the network 172.21.0.0 255.255.255.128?

mcuberly

theres 9 bits for subnets. thats more than 2.

this is a class b address so you have the full 3rd octet plus the 1 bit from the 4th octet.

Christopher Dobkowski

it's 255.255.255.128 = /25 ... = 11111111.11111111.11111111.10000000...

networks in this example would be :

a) 172.21.0.0

and

b) 172.21.0.128

mcuberly

so
11111111.11111111.11111111.10000000
the class is B so
11111111.11111111.00000000.00000000 is the default mask
which leaves 9 bits for subnets, and 7 bits for hosts
or 512 subnets, and 126 hosts


the subnet mask determines how may bits are available for the subnets

Christopher Dobkowski

Ooooooooohhhh!!!!! Bingo!

Thankx!