Subnet Mask, Decimal, Slash Notation.

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.


128.000.000.000 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

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
1000=8
10000=16
100000=32
1000000=64
10000000=128

"Robert Bollinger" <(E-Mail Removed)> wrote in
message news:C9144721-E33B-4ABC-A33A-(E-Mail Removed)...
> 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.
>
>
> 128.000.000.000 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

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".



"Bill Grant" wrote:

> 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
> 1000=8
> 10000=16
> 100000=32
> 1000000=64
> 10000000=128
>
> "Robert Bollinger" <(E-Mail Removed)> wrote in
> message news:C9144721-E33B-4ABC-A33A-(E-Mail Removed)...
> > 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.
> >
> >
> > 128.000.000.000 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
>
>

Robert Bollinger wrote:
> 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".

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