Subnetting Class B Question

chezbezchezbez Member Posts: 7 ■□□□□□□□□□
in CCNA & CCENT
Hey Guys,

i came across this question on subnettingquestions.com - Free Subnetting Questions and Answers Randomly Generated Online

What is the subnet addesss of 172.16.159.159/22?

Now from working out the subnet mask i understand the increment is going to be 4.

172.16.0.0
172.16.0.4
E.C.T.

However seeing as my maths isn't the best and i will hardly have time on my side in the exam to go through all those hundreds of numbers. Could you help me on how i would get not only the answer but even close to those numbers.

Note: The answer should be 172.16.156.0

I really appreciate any help you could provide as i really want to crack class b subnetting.
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Comments

  • FloOzFloOz Member Posts: 1,614 ■■■■□□□□□□
    It would actually increment in the 3rd octet not the 4th.

    So
    172.16.0.0
    172.16.4.0
    .
    .
    .
    172.16.156.0 - 172.16.159.255
    172.16.160.0

    In this situation I was able to figure it out quickly because I knew 156 is divisible by 4 :)
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  • RouteMyPacketRouteMyPacket Member Posts: 1,104
    We are working with the following

    172.16.156.0 - 172.16.159.255

    22 bits were used right?

    11111111.11111111.11111100.00000000

    So from that we know we will be working with the 3rd octet, that is where the changes will take place.

    The question is simple as it is only asking you the "subnet" address.

    The subnet is 255.255.252.0

    The network address is 172.16.156.0 and the broadcast is 172.16.159.255
    Modularity and Design Simplicity:

    Think of the 2:00 a.m. test—if you were awakened in the
    middle of the night because of a network problem and had to figure out the
    traffic flows in your network while you were half asleep, could you do it?
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