One Comment on “Which address range efficiently summarizes the routing table of the addresses for router Main?”

1. Aldrin Angeles says:

   July 30, 2014 at 1:42 pm

   To summarize these networks efficiently we need to find out a network that “covers” from 172.16.1.0 -> 172.16.13.0 (including 13 networks < 16). So we need to use 4 bits (24 = 16). Notice that we have to move the borrowed bits to the left (not right) because we are summarizing.

   The network 172.16.0.0 belongs to class B with a default subnet mask of /16 but in this case it has been subnetted with a subnet mask of /24 (we can guess because 172.16.1.0, 172.16.2.0, 172.16.3.0… are different networks).

   Therefore “move 4 bits to the left” of “/24″ will give us “/20″

   
   
   
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