Rooting a Clone ??

i have heard many things on how much light i should give a clone (cutting), that i am trying to make grow roots.

so what light cycle should i give my clone, that i want to grow roots ??
24 hours of straight light??
18/6 ???

or what?? someone help plz

18/6 works

I put mine 24hrs under fluoros and cfls

alright, well im going to stick with what mogie said, just because i already have them on 18/6.
the person i got the clone cuttings from, said to keep them on 24hrs.....he always uses a areoponics* device to get cuttings to root.

i have 1 cutting in a areponics device,and one in soil
is it ok to have both on 18/6??? my guess is yes