reapplying period for visit visa

[billboard]

Hi,
I would like to know if the visiting visa gets rejected, then within how many days can we reappply. Is there any conditions for reapplying. Please advise.
Also have anyone applied for visit visa for their parents from singapore US consulate.
Thks

[Murali]

There is no official time frame, it is good to have few weeks/Months of gap, depending on the refusal type and situation you can re-apply within minimum of 3 days.