Subnet identifiers

angry_monkey_showangry_monkey_show Member Posts: 11 ■□□□□□□□□□
Hi! I'm studying to take the net+ exam, and I've came across a question on a practice exam that I need a little explaination on.

The question involved assigning the highest IP on a subnet to the router.
The identifier assigned to the subnet is

The part that's giving me trouble is the "/20" apparently the answer is that the highest IP within that given range is, but I have no idea what the /20 has to do with the subnet identifier. If anyone has any links, or can explain this to me, I would really appreciate it.


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    EdTheLadEdTheLad Member Posts: 2,111 ■■■■□□□□□□
    An IP address consists of 32 bits, i.e. 4 x 8 bits
    /20 means a 20 bit subnet mask i.e
    /16 would be
    Networking, sometimes i love it, mostly i hate it.Its all about the $$$$
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    eurotrasheurotrash Member Posts: 817
    01100000.00000000 = x.x.96.0
    11110000.00000000 = /20 (relevant portion)

    the second row is the subnet mask, and the zeros determine the host portion. the /20 means the mask (1's portion) is 20 bits long (though i've only showed half the mask).

    so the subnet is 0110 and you have 0000.00000000 for the hosts.
    highest IP = (0110)1111.11111110 (all 1's is for the broadcast).
    which equals x.x.111.254
    witty comment
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    angry_monkey_showangry_monkey_show Member Posts: 11 ■□□□□□□□□□
    thanks. I wasn't thinking in terms of binary at all icon_rolleyes.gif !!
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