This paper reports on the state of the art of virtualization technology for both general purpose domains as well as real-time domains. There exits no entirely instantaneous data transmission/transfer. There always exist a delay while transmitting data, either in the processing or in the medium itself. However most systems are designed to function appropriately with a delay tolerance. This delay, inevitably, is affected when operating with an extra layer, the virtualization. For real time systems it is crucial to know the temporal limits in order not to surpass them. Introducing virtualization in the real-time domain therefore requires deeper analysis by making use of techniques that will offer results with deterministic execution times. The study of time in systems and its behaviour under various possible circumstances is hence a key for properly assessing this technology applied to both domains, especially the real-time domain.