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Subnetting help

shatteredzmanshatteredzman Registered Users Posts: 3 ■□□□□□□□□□
Hello, I have some subnetting questions. I am not sure where to begin with these problems. After trying to study for over 6 hours I figured I would come here for some help.

I need to take 139.68.0.0/16 and subnet it into two subnets (subnet1, subnet2) of the same size. I need to find the first and last network and broadcast address for the blocks.

I then need to take subnet1 and allocate 64 blocks of 512 IP addresses. Subnet2 needs 128 blocks of 256 IP addresses. I need to find the first and last network and broadcast address for the blocks.

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    sratakhinsratakhin Member Posts: 818
    Your two subnets will have thew following addresses:
    139.68.0.0/17
    139.68.128.0/17

    Thus, the first network in the first subnet will be 139.68.0.0/23 with the broadcast 139.68.1.255
    The last network in the first subnet will be 139.68.126.0/23 with the broadcast 139.68.127.255

    The first network in the second subnet will be 139.68.128.0/24 with the broadcast 139.68.128.255 (that was easy)
    And the last network will be 139.68.255.0/24 with the broadcast 139.68.255.255

    No binary stuff, figured it out while I was typing.
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    shatteredzmanshatteredzman Registered Users Posts: 3 ■□□□□□□□□□
    Thank you.
    Okay so I am a bit relieved, I got the first two ip addresses correct.

    Okay now I need to allocate 128 blocks of 256 ip addresses in the 139.168.126.0/24 address. Like before I need to find the first and last network and broadcast address and network address for the blocks.

    I really hate to be a bother, but could you explain how you got these answers? This is the first of a couple assignments I will have over this. If I don't know how to do this now, I won't be able to figure it out on my own.
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    sratakhinsratakhin Member Posts: 818
    You cannot allocate 128 blocks of 256 IP addresses in a class C network. You would have to use a /17 mask to do it.

    I can't really explain the logic I use when I do subnetting. I practiced it a lot when I prepared for CCNA, so it's kind of obvious to me now.
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    shatteredzmanshatteredzman Registered Users Posts: 3 ■□□□□□□□□□
    sratakhin wrote: »
    You cannot allocate 128 blocks of 256 IP addresses in a class C network. You would have to use a /17 mask to do it.

    I can't really explain the logic I use when I do subnetting. I practiced it a lot when I prepared for CCNA, so it's kind of obvious to me now.

    Hmm you are right. I guess I misread the question. It says I need to use the last part of 139.68.128.0/17
    I'm sorry if I seem clueless, but it is because I am clueless.
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