subnettingquestions.com

Upon looking at the site it is mentioned that subnet zero is allowed. My question is when allowing subnet zero is it true that one does not - 2 in your formula to work out valid subnets? The reason I am asking is because with all my answers I get 2 less than their correct answer. In the exam will it be specified if we should allow subnet zero?

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Comments

nicklauscombs

if subnet zero is allowed you will have 2 extra subnets so yes do not - 2.
not sure on the Microsoft exams but its quite clear when to use it and when not to use it on the cisco exams.

nazzeem

nicklauscombs wrote:

if subnet zero is allowed you will have 2 extra subnets so yes do not - 2.
not sure on the Microsoft exams but its quite clear when to use it and when not to use it on the cisco exams.

So with Microsoft exams do we use subnet zero or not? Or will it be specified to use subnet zero?

undomiel

I believe that the exam will mention whether a router is RFC 1878 or not. I'd swear I saw some posts somewhere mentioning that. Also whether a router is RFC 1542 (DHCP relay) will be mentioned as well.

NetAdmin2436

MS Press Book:Exam 70-291, Chapter 2, lesson 3, page 2-29.

"To determine the number of subnets available within an address space, simply calculate the value of 2^y, where y equals the number of bits in the subnet ID. For example, when the network address space 172.16.0.0/16 is subnetted to /24, 8 bits are reserved for the subnet ID. Therefore, the number of available subnets is 2^8, or 256. You do not usually need to subtract 2 from this total because most modern routers (including the Routing and Remote Access service in Microsoft NT Server, Microsoft 2000 Server, and Windows Server 2003) can accept a subnet ID made up of all 1's or all 0's."

I'm currently reading through this chapter in the book and remembered this post from a while ago, so figured I'd throw this out there.