10 Replies to “IP Addressing In Depth

  1. For the broadcast address of the 3rd question on quiz 1, why is it counted as 64 and not 16?
    11111111 11111111 11111111 11110000 for /26 1s, doesn’t that mean 4 in the last octet giving you 256-240=16?

    1. Do you mean 172.16.111.1/30?
      Start by looking at the binary:
      1010 1100 . 0001 0000 . 0110 1111 . 0000 0001

      The CIDR notation is /30, which means the first 30 bits are the network address.
      The first 30 bits then, are 172.16.111.0

  2. Hello,

    For the network address on question number 4 of Quiz 1 i am not sure how you got 203.77.56.0

    Shouldn’t it be 203.77.54.0? If not could you please explain?

  3. The value of the third octet in is 252, subtracting this from 256 gives four.

    In the four times tables, the closest values to 56 are 56 and 60, meaning that 203.77.56.0 is the network IP address, and 203.77.59.255 is the broadcast address.

    I think you might want to double-check your maths

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