Subnetting question

kicker22

I have a question here..
what is the maximum subnet bit and number of subnets in a class C?

I thought that each subnet in class C will Have a maximum of 254 hosts...

but friend of mine told me its 6 bits for subnets
and 62 maximum number of subnets..


need explanation!

thank you,

Kicker

isadore

Your friend is correct. You cannot use 7 bits for subnet as that would only give you a 2 host network, both of which are invalid addresses (subnet ID and Broadcast). So we use 6 bits, giving us 64 network of 4 addresses each. BUT the top and bottom networks are not allowed either. So we toss them giving us 62 networks useable.

kicker22

hey thanks..

but tell me... do u recommend me to go for CCISP after CCNA?
or wassup!
let me know

kicker

2Tahoe

Another way of looking at this Class C problem:
default mask is 255.255.255.0
That leaves 8 bits in the 4th octet that can be used for subnetting.
You have to borrow at least 2 bits for the subnets and leave at least 2 bits for the hosts because you can't use the first and last subnet or the first and last host address
Using the formula 2 to the nth power -2 (where n = number of bits borrowed)
2 to the 6th power = 64-2 = 62 usable subnets with 2 usable host addresses