for help, class B

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You have a class B network with a mask. Which of the
below are true of this network? (Select all valid answers)

A. There are 254 usable subnets.
B. There are 256 usable hosts per subnet.
C. There are 50 usable subnets.
D. There are 254 usable hosts per subnet.
E. There are 24 usable hosts per subnet.
F. There is one usable network.

Answer: A, D

I don't think A is right,because i think there are 256 usable subnets

Re: for help, class B
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A is correct if you don't use the first and last subnet (very very old
If you also use the first and last subnet (default nowadays) there are 256


Re: for help, class B

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Yes, as the previous poster stated this is an extremely old way of
determining the number of  subnets.
Good training materials in recent years stated things such as "assume the
command ip subnet zero has been issued", or very clearly that you were to
calculate the number of "ususable subnets, as opposed to the total number of

However, the concept of "useable" v. "total" subnets has now been dropped
from all new (2007) Cisco branded training material and certs. If you are
using training resources that include questions with the above answers it is
now out of date and should discarded.


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