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General IP class question

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  • General IP class question

    I am pretty new to networking, and I am studying CCNA and Net+ to get sometime this year. I am reading a bunch of detailed stuff, but I have a basic question.

    So lets take what I know of IP's (N- network, H- host)

    Class A - N.H.H.H (~6m)
    Class B - N.N.H.H (~65k)
    Class C - N.N.N.H (254)

    Class A - 0-126
    Class B - 128 - 191
    Class C - 192-223

    So, is it possible to mix those two rules? Example: N.H.H.H (class A) using 192 (class C) as its network ID? Would work as a Class A? Simple question, but it seems like a simple mistake if not. I need to understand IP and sub-netting better. All the networks I work with are already set up.

    I feel like I may be touching on CIDR and Classful, but not 100% sure. I need to research that next.
    Last edited by zang8027; 26th December 2012, 05:19.

  • #2
    Re: General IP class question

    There is no reason why it would not work, but would break the protocols for IP, where ranges of the available IP space were designated as being for Class A (or B or C) use.

    In your example, the Class A would be 192.x.x.x and would span the public and private range
    Tom Jones
    MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
    IT Trainer / Consultant
    Ossian Ltd

    ** Remember to give credit where credit is due and leave reputation points where appropriate **


    • #3
      Re: General IP class question

      Or you could do it the "other way" and use the 10.x.x.x . eg, or if more Hosts are needed,

      FYI, Class A - N.H.H.H (~6m) is actually, Class A - N.H.H.H (~16m)
      Joined: 23rd December 2003
      Departed: 23rd December 2015


      • #4
        Re: General IP class question

        ah ok. I was wondering if it would work or not. Thank you