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IP address range

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  • 10-01-2015 12:28am
    #1
    GarIT
    Registered Users Posts: 8,671 ✭✭✭


    Hopefully somebody can clear this up for me as I've an exam in the morning. I was given a subnet address and asked to work out the maximum and minimum value for the hosts. e.g. for the subnet address 149.157.64.0 /18 I would have worked out that there are 14 bits left to address the hosts, with a minimum binary value of 14 0's and a max value of 14 1's. I would have just added the 14 1's to the subnet address to get the max address of 149.157.127.255 and given the minimum as 149.157.64.0. The answer gives [149.157.64.1, 149.157.127.254] as the range. Does anyone know why you can't use the 1 plus/minus either side of the answer as I calculated?


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    #2
    moc moc a moc
    Registered Users Posts: 1,299 ✭✭✭moc moc a moc


    You're almost there, but you forgot that the first and last IP addresses in any subnet are reserved (network address and broadcast address respectively). They can not be assigned to actual host devices, therefore the first and last addresses for hosts are the ones given in the answer you got back. If the question had asked for first and last addresses (as opposed to hosts specifically) you would have been correct.


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    #3
    T-K-O
    Registered Users Posts: 6,309 ✭✭✭T-K-O


    Cisco love these questions on their exams, for hosts remember n-2.


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