Botnet problem has reached epidemic levels in recent months, with the continued growth of large-scale botnets. Researchers have been taking steps to disrupt botnets of late, with some notable successes. Mega-D, also known as Ozdok, is a botnet that has been in operation for more than a year. Researchers at FireEye took all but four of the C&C servers offline and took six of the domains offline by working with the registrars involved. The botnet controllers likely will be looking for a new channel through which to communicate with their now-orphaned bots.
Source: https://threatpost.com/how-take-down-botnet-110909/73054/