Memorizing Block sizes

[TKelley]

All the block sizes...what is the most common ones I need to remember?
Tim

[aguilera]

Which ones are the common ones you need to remember? All of them.

Sounds hard but check this out....

/9, /17 and /25 each use 1 bit of subnetting 2^1 = 2 Networks created

/9, /17 and /25 each have a mask of .128 Right? How do we get that mask?

1
2 6 3 1
8 4 2 6 8 4 2 1

1 0 0 0 0 0 0 0

What bit does my network stop on? The 128 bit. Guess what? That is our block size!

Networks we create are 0 and 128


/10, /18 and /26 each use 2 bits of subnetting 2^2 = 4 Networks created

/10, /18 and /26 each have a mask of .192

1
2 6 3 1
8 4 2 6 8 4 2 1

1 1 0 0 0 0 0 0

What bit does my network stop on? The 64 bit. Guess what? That is our block size!

Networks we create 0, 64, 128 and 192


/11, /19 and /27 each use 3 bits of subnetting 2^3 = 8 Networks created


/11, /19 and /27 each have a mask of .224

1
2 6 3 1
8 4 2 6 8 4 2 1

1 1 1 0 0 0 0 0

What bit does my network stop on? The 32 bit. Guess what? That is our block size!

Networks we create 0, 32, 64, 96, 128, 160, 192 and 224


See the pattern?