Journal of Information Security Research Alaa Hassan, Milena Radenkovic 6 2 2015 http://www.dline.info/jisr/fulltext/v6n2/v6n2_1.pdf MANETs are open and cooperative networks and can be formed quickly and without any complex infrastructure. These are very useful characteristics for fast and easy connectivity, however this poses severe security threats. In this paper, we only focus on the security threats posed to most popular MANET routing protocol AODV by black hole and flooding attacks. A Simulation study has been conducted in ns-3 to compare the performance of preventive schemes FAP and AMTT in case of flooding and black hole attacks on MANET’s. The performance is analyzed based on throughput, message delay and routing overhead.