basic subnetting troubles

chehornchehorn Posts: 2Registered Users ■□□□□□□□□□
This could just be in issue with me not understandingsubnetting fully. I am following the CBT nuggets series and have been practicing subletting but a few problems throw me off. For example When trying to get 200 networks in a class a ip, i see that it will take 8 bits to reach that number so we need 8 additional bits are added to subnet mask making it /16. What I'm having trouble with is finding the bit range for the range of subnets. From what I remember you take the last bit column and use iys value. For example /18 would be 64. But I. This scenario I am given 1...pretty confused any help would be great.


  • tecnodog7tecnodog7 Posts: 129Member
    Suppose we have a networking with a sub net mask of and we need to get 200 network.

    First lets convert 200 into binary
    200 = 11111111 = 8 bits

    Now lets convert or /16 into binary.

    Now let's start adding network bits where its needed
    so the new binary is
    Now let's take the smallest interval which is a 1. (How did i get this? 128,64,,32,16,8,4,2,1)

    Now that we found for smallest binary value how lets find the range. - (To not here we only have 254 usable host 0.0 network , 0.255 bcast - -
    And so now. So let's find out how many network we have
    the easiest way to do that is 2^n (n being your network bit) so if we do this 2^8 = 256

    Hope this helps
  • CCIE Wanna BeCCIE Wanna Be Posts: 95Member ■■□□□□□□□□
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  • chehornchehorn Posts: 2Registered Users ■□□□□□□□□□
    Of course! Thanks for laying it out so nicely for me, makes complete sense now. Was way over thinking it. Appreciate the quick response.
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