One Comment on “Which IP addressing scheme best defines the address range and subnet mask that meet the requirement and waste ”

1. San says:

   February 13, 2013 at 12:35 pm

   I don’t understand why and found the answer here:

   http://www.9tut.com/ccna-subnetting-questions-4 – Q.8

   Explanation

   We need 113 point-to-point links which equal to 113 sub-networks < 128 so we need to borrow 7 bits (because 2^7 = 128).

   The network used for point-to-point connection should be /30.
   So our initial network should be 30 – 7 = 23.

   So 10.10.0.0/23 is the correct answer.

   You can understand it more clearly when writing it in binary form:

   /23 = 1111 1111.1111 1110.0000 0000
   /30 = 1111 1111.1111 1111.1111 1100 (borrow 7 bits)

   
   
   
   0

   
   
   
   0