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Classful Address Analysis

Discussion in 'Routing & Switching' started by Zunar-J-5/9, Mar 19, 2015.

  1. Zunar-J-5/9

    Zunar-J-5/9 New Member

    Hello all,
    I am studying for ccent (icnd1). in chapter 12 of the cisco cert guide, it is talking about "classful" addresses.
    on page 345 (if you have the book) it has a chart which summarizes as follows.

    Class A address: use 1oct for network, 3oct for host.
    Class B adddress: use 2 oct for network 2 for host
    Class C address: use 1 oct for network 1 for host.
    so far so good.
    It gives examples of determining the network ID and Broadcast Address.
    For Net ID
    class A X.0.0.0,
    Class B X.X.0.0
    class C X.X.X.0
    Broadcast Address:
    A X.255.255.255,
    B X.X.255.255
    C X.X.X.255

    All is good with the world :)
    in the chapter pretest (do I already know this) the last question is:
    Which of the following is network Class A,B, or C network id.

    Well shoot! I just figured it out. BRAIN FART
    so the answer is B because it is class C and the last octet is 0. DUH...

    so it turns out, Ali is good with the world after all... :)
    so i thought I'd post this after all the typing.
    I don't know how many times I've tried explaining a problem to someone only to realize the solution
    just by talking about it.
  2. elgatito71

    elgatito71 New Member

    Thanks for the post op very helpful...

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