Subnet Mask, Decimal, Slash Notation.

Discussion in 'Server Networking' started by Robert Bollinger, Oct 6, 2007.

  1. Hey Guys,

    I am hoping that you can assis me with this question, as i have hit a wall.
    I need to have this explained to me, this is in my 70-291 book on page 2-16. has a binary value of 10000000.00000000.00000000.00000000

    This is mask to binary conversion, i can memorize this all day but would
    rather understand how and WHY it works like the above example.

    How come a binary notation of 10000000 = 128? how is that done? why does it
    start at 128? and not at 1?

    HOw are the bit's determined and converted into a dotted.decimal address?

    i understand this: 32-bit ip addy is 4 groups of eight bits at different
    placements (starting) with 0-8 9-16 etc.

    theses are called octets which means eight or of eight. Wht i dont
    understand is as stated above.

    I am sorru of this is not clear but i am fried on this one.

    Please advise... Thank you.

    Robert Bollinger, Oct 6, 2007
    1. Advertisements

  2. Robert Bollinger

    Bill Grant Guest

    An octet is eight bits. In binary, each column can only have the value of
    zero or one.

    So binary 10 = 2 decimal
    100 = 4
    Bill Grant, Oct 7, 2007
    1. Advertisements

  3. Bill thanks for your answer.

    Can you be more specific with more examples about that, i am kinda getting
    it but there is a difference between "I think I know" and "I have a clue" and
    "I really know, yes i can fix your network".
    Robert Bollinger, Oct 7, 2007
  4. Robert Bollinger

    jorgen Guest

    In our normal decimal system (base 10)

    1 is one
    10 is ten
    100 is hundred

    each time you put a zero in, the value goes up by a factor of 10. In the
    binary system (base 2) the value goes up by a factor of 2:

    1 is one
    10 is two
    100 is four
    10000000 is 128
    01000000 is 64
    jorgen, Oct 7, 2007
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.