[OT] CIDR Mask calculation

[Rob Andrews]

On 12-Oct-2006 17:52.11 (BST), Dave Ihnat wrote:
 > Anyway, the addresses you gave, converted to binary, are:
 > 
 >   219.128.0.0    : 11011011.10000000.00000000.00000000
 >   219.137.255.255: 11011011.10001001.11111111.11111111
 >                                ^
 > The last bit that is invariant between the two is marked with the caret;
 > converting back to a decimal dotted-quad (you can use 'dc' again--to set
 > the input to binary, simply change the 'o' operand in the above example
 > to an 'i', then input the binary value and print.)
 > 
 >   Mask
 >   255.240.0.0    : 11111111.11110000.00000000.00000000
 > 
 > or, in conventional notation, 219.128.0.0/12.

That's 219.138.0.0 - 219.143.255.255 though :)

-- 
rob andrews                       :: pgp 0x01e00563 :: rob at choralone.org