Mobile ad hoc network (MANET) is dynamic in nature and vulnerable for several attacks to be arising in it. Mobile nodes frequently disconnect and join the network; they can arbitrarily moves from one place to another. In present-day wireless communication scenario, Mobile ad hoc network (MANET) plays a very important role, as it consists of many autonomous nodes which communicate together to form a proper communication network. Each node in a network will move in random path, so that nodes direction will change frequently. This paper describes the features, application, flooding attack and black hole attack in the MANET implemented on AODV protocol. The simulation work is carried out in Network Simulator (NS2.34). The performance analysis is done Nodes with 20 to 60 nodes were used in the AODV routing protocol simulation to produce energy-efficient outcomes, with the flooding attacks and the interruption of blackhole attacks. The average delay, routing overhead, packet drop rate and packet delivery rate are calculated. By the simulation it has been evaluated that in flooding attack the routing overhead is more as compared to the black hole attack. A comparative study is also done on these parameters for all three scenarios. Also we simulated the attack in various wireless ad-hoc network scenarios and have tried to find a response system in simulations.