The use of discrete-event simulators in the design and development of distributed systems is appealing due to their efficiency and scalability. Their core abstractions of process and event map neatly to the components and interactions of modern-day distributed systems and allow designing realistic simulation scenarios. MONARC, a multithreaded, process oriented simulation framework designed for modelling large scale distributed systems, allows the realistic simulation of a wide-range of distributed system technologies, with respect to their specific components and characteristics. In this paper we present an innovative solution to the problem of evaluating the dependability characteristic of distributed systems. Our solution is based on several proposed extensions to the simulation model of the MONARC simulation framework. These extensions refer to fault tolerance and system orchestration mechanisms being added in order to asses the reliability and availability of distributed systems. The extended simulation model includes the necessary components to describe various actual failure situations and provides the mechanisms to evaluate different strategies for replication and redundancy procedures, as well as security enforcement mechanisms.