of classful boundaries and guns n roses...

who knew that slash plays at the classful boundary...
watch him play welcome to the jungle below...

255.0.0.0 255.255.0.0 255.255.255.0
/8                      /16                     /24
some call it prefix, it looks like slash to me... go slash...

4 octets delimited by dots, 8 bits per equals 32, add or subtract, your preference... like jack swigert said in apollo 13, "i know how to add"

/8 + 2 = /10 or 255.192.0.0 why? because i know how to add...

128 is 1, 192 is 2, 224 is 3, 240 is 4, 248 is 5, 252 is 6, 254 is 7 and 256 is 8 or the classful boundary

/16 + 7 = /23 or 255.255.254.0... why is 254 significant here... because it is the first instance of NOT 1...

it is in the first instance of NOT 1 where you'll hear slash play...

shortcut, i don't think so... i know how to add...

/25 is 24 plus 1... 24 is the classful boundary of C or 255.255.255.0...  we can't have any more 1's so we spill into the fourth octet with the 1... 128 is 1, 192 is 2, 224 is 3 and so on...
255.255.255.128 or 24 + 1

/19 is 16 + 3 or 255.255.224.0
128 + 64 + 32 = 224

1 is 128, 2 is 128 + 64, 3 is 128 + 64 + 32, 4 is 128 + 64 + 32 + 16 or 240, you add the rest...
1 is 128, 2 is 192, 3 is 224, 4 is 240, 5 is 248, 6 is 252, 7 is 254 and 8 is 256...
so why isn't 256.256.256.256 the all one's?
because zero is a number and 0 to 255 is 256
255's or all 1's or all f's is a broadcast sweet child o' mine...