Richard Burdette wrote: > > A prep test I am using has a question for which I disagree with > the answer. Here is the question… > > If I had a Class B address, what subnet mask would I use if I > wanted to split it into 8 class C addresses? > > > a.255.255.240.0 > b.255.255.255.0 > c.255.255.248.0 > d.255.255.254.0 > > The answer from the test is “c”. > > I think the answer is not even listed; 255.255.224.0 because to > add eight additional subnets we need 2^3=8 bits of subnet which > equates to 224 of mask. Am I right or wrong? > > Rich > >
The question sucks and so do the answer choices. Eight *addresses* per subnet or eight subnets? If the former, a mask of 255.255.255.248 would be required - not 255.255.248.0. If the latter, I'd go with you (sorta). Or perhaps a. if subnet zero weren't allowed for some reason (but then you'd have 15 subnets plus subnet zero - not eight!). Nothing you do with a subnet mask makes a class B a class C. If it was class B before you subnetted it, it isn't going to fall into the class C range of addresses all of the sudden is it? If by "class C" they mean a subnet with 254 host addresses, your answer isn't right either. Your subnets (/21) would have 8190 hosts. In that case, there isn't a valid answer at all because a class B subnetted for 254 hosts will have somewhere in the neighborhood of 255 subnets. I would be wary of the "practice" test as a whole. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=58573&t=58569 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
