The trick to questions like these is they're asking what subnet 
"structure" would be necessary to contain the required configuration. I 
saw similar ones on the cisco tests, actually. They use private space 
addresses just to give you a network to work with and actually confuse 
the issue, and yet keep from using someone's assigned address space in a 
question. Probably think it outwits the kiddies or something.

In questions like this remember a version of the old standby equation 
you learned from cisco:  2^n - 1 > X  where n and X are defined as the 
pairs (n=network bits; X= number of networks wanted) or (n=host bits; X= 
number of hosts per subnet wanted). Thus, from your example with 10 
subnets required:

2^n -1 > 10   --->   2^n > 10  ---> (1,4,8,*16*,32,64,...) > 10,  so n = 
4 and the mask is 255.255.255.240 as Entelin stated.

I don't it's all that terribly written, honestly. They feel they have to 
give you at least the given network/mask, so that you know which octet 
the subnetting occurs in, although if you're only talking 10 hosts per 
subnet it should be obvious which one you're in, right? ;-)

Entelin wrote:

>The correct answer is 255.255.255.240, which makes sence of course if
>you take out the line about their ISP. Its just badly written.
>
>On Sun, 2002-08-18 at 00:31, Kevin Brown wrote:
>  
>
>>>The test content is easy, but I cant beleive some of these questions...
>>>I guess Micro$oft's way of rasing the bar on their tests is making them
>>>progressivly worse written. I biched about this the last test but damnit
>>>this is insane!  I am staring at a test question right now that makes no
>>>sence, in their senario they have an ISP give an entire class C of
>>>internet addresses (255) to a office of 100 computers, the ip address
>>>range isnt a valid range for internet use, a company that size
>>>realisticly wouldent use more than 3 of the 255, and they specify a 24
>>>bit subnet or 255.255.255.0 . Then after giving you all this completely
>>>bogus info they ask an off the wall question like what subnet mask you
>>>would use for your network if you wanted 10 subnets and 10 hosts per
>>>subnet.  Even if that did make sence to do, they already specified the
>>>subnet mask as 24 bits. So you have to just guess at what they are
>>>actually getting at.
>>>      
>>>
>>Welcome to Microsoft logic.  Of course a class C can be further divided down
>>into smaller subnets (ASU divides two class Bs into 64 address chunks
>>[255.255.255.192]).  So the network would need to be divided into at least 12
>>IPs per subnet from the class C.  Wish I had that subnet calculator program that
>>was on my system at work.  Makes figuring this out so much easier.
>>
>>    
>>
>>>Thank god for Braindumps, if I dident have these I fear the only way to
>>>pass these tests would be to stick a crayon in my brain.
>>>
>>>Cisco's tests are actually well written. This is probably one good
>>>reason why theres so many "Paper MCSE's" around, They get out in the
>>>feild and dont have any grasp on the right way to do things. But then
>>>again if people had a grasp on the right way of doing things there would
>>>be more *nix and less windows.
>>>
>>>Latter!
>>>
>>>________________________________________________
>>>See http://PLUG.phoenix.az.us/navigator-mail.shtml if your mail doesn't post to the list quickly and you use Netscape to write mail.
>>>
>>>PLUG-discuss mailing list  -  PLUG-discuss@lists.plug.phoenix.az.us
>>>http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
>>>      
>>>
>>________________________________________________
>>See http://PLUG.phoenix.az.us/navigator-mail.shtml if your mail doesn't post to the list quickly and you use Netscape to write mail.
>>
>>PLUG-discuss mailing list  -  PLUG-discuss@lists.plug.phoenix.az.us
>>http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
>>    
>>
>
>
>________________________________________________
>See http://PLUG.phoenix.az.us/navigator-mail.shtml if your mail doesn't post to the list quickly and you use Netscape to write mail.
>
>PLUG-discuss mailing list  -  PLUG-discuss@lists.plug.phoenix.az.us
>http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
>
>  
>