# Question about Summarization

alu408
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**45**Member ■■□□□□□□□□
in CCNA & CCENT

Heres an example. Address 192.168.144.0/20 so whats the range of host address that would be forwarded according to this summary?

/20 is 255.255.240.0

Third octet is block size of 16. And the starting summary is 144, the next block of 16 is 160. so the network summary range is 144-159 in the third octet. I am trying to understand why the range ends in 159 and not 160 if the next block is 160? I am guessing because we do not use the last address we just -1. which equals 159. Can someone explain please. Thanks!

/20 is 255.255.240.0

Third octet is block size of 16. And the starting summary is 144, the next block of 16 is 160. so the network summary range is 144-159 in the third octet. I am trying to understand why the range ends in 159 and not 160 if the next block is 160? I am guessing because we do not use the last address we just -1. which equals 159. Can someone explain please. Thanks!

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## Comments

38Member ■■□□□□□□□□It's because 160 is the beginning of the next block of 16 (192.168.160.0 - 192.168.195.255 /20).

192.168.144.0 to 192.168.159.255 is actually a block of 16 because you have to count from 144 to 159, inclusive.

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160MemberSince it starts from "0" as simple as it can be. Since everything can only be in the powers of 2 start counting from 0 and everything starts from even number and ends with odd.

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