IPv4 Subnetting Question

Radio2006Radio2006 Junior MemberMember Posts: 28 ■□□□□□□□□□
Hello all,
I am studying for the CompTIA Network+ exam and have a question about subnetting. The example given is that a cafe requires 3 different networks. One for guests, one for employees and another for wireless. The formula for determining how many subnets you create is 2^y. In this case, we want to create 3 therefore, 2^2 which is 4. So why is it that in a subnet of, you only go back two bits vice 4? I can't help but think that there is some common knowledge here that I am missing. I'm thinking that you move one "digit" for every two subnets...?
As always, any assistance is greatly appreciated.


  • dpjackal89dpjackal89 Member Member Posts: 81 ■■□□□□□□□□
    I'm not exactly sure what you're asking.
  • tycar86tycar86 Member Member Posts: 34 ■■□□□□□□□□
    I used the IPv4 Subnetting TechNote to learn subnetting. Maybe that will clear your question up.
  • Radio2006Radio2006 Junior Member Member Posts: 28 ■□□□□□□□□□
    @dpjackal89...I'm not that sure either. But luckily, tycar86 cleared it up for me. Thanks again. The question I had was in part one...because subnets are created in powers of two. When you want to create 3 additional subnets x in 2^x will be two. Which will give you a total of 4 subnets. When moving the "line" when you have the subnet expressed in binary, you only move it one digit for every two subnets. Two digits for four subnets and so forth. The tools I am using didn't go into detail on that front, it just gave the formual.
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