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How do you work out this??

I3astardsI3astards Member Posts: 40 ■■□□□□□□□□
in Network+
What is the first valid host on the subnetwork that the node 192.168.152.93 255.255.255.248 belongs to?
Answer: 192.168.152.89



I just dont know how they got that answer. Can you show your working please?
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    Pratt2Pratt2 Member Posts: 66 ■■□□□□□□□□
    I3astards wrote: »
    What is the first valid host on the subnetwork that the node 192.168.152.93 255.255.255.248 belongs to?
    Answer: 192.168.152.89



    I just dont know how they got that answer. Can you show your working please?


    255.255.255.248 = 11111111.11111111.11111111.11111000 = Mask
    192.168.152.93 = xxxxxxxx.xxxxxxxx.xxxxxxxx.01011101 = node

    So, the first 3 octets of the node address are part of the subnet id, and in the last octet of the node address the first 5 numbers are also part of the subnet id.

    01011:101 Mask:Possible hosts in subnet

    To find first valid host, take the host portion and change it to equal 1.

    01011:001

    Then change that binary back to decimal.01011001=89.
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    I3astardsI3astards Member Posts: 40 ■■□□□□□□□□
    ahhh, OK i see

    I worked it out slightly differntly.

    256 - 248 = 8 (increments)

    192.168.152.88 = first increment

    192.168.152.89 = first host in that increment


    is this a valid way of working it out?
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    Pratt2Pratt2 Member Posts: 66 ■■□□□□□□□□
    I'm actually kind of confused by your explanation. Are you trying to avoid converting to binary and back? I'm not sure you should ever be playing with numbers larger than 255. Subnetting confused me until I just sucked it up and stopped trying to find shortcuts.
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    I3astardsI3astards Member Posts: 40 ■■□□□□□□□□
    Pratt2 wrote: »
    I'm actually kind of confused by your explanation. Are you trying to avoid converting to binary and back? I'm not sure you should ever be playing with numbers larger than 255. Subnetting confused me until I just sucked it up and stopped trying to find shortcuts.


    Yeah, im basically do a short cut I suppose.

    take the host portion away from 256 to find out how big the subnet increments are then from there work out where the next subnet starts and whether the number in question falls into it.
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