MANETS are the temporary networks which are dynamic and self-maintainable. As being dynamic in nature and without any fixed infrastructure security becomes a great concern in MANETs. In MANETS we have different types of security attacks like black hole, worm hole and grey hole but in this paper we are only focusing on the black hole attacks. These black hole attacks poses a serious security threat to the routing services by attacking the reactive routing protocols resulting in drastic drop of data packets. AODV (Ad hoc Ondemand Distance Vector) routing being one of the many protocols often becomes an easy victim to such attacks. In such kind of attacks a node advertise a shortest path for the given route request and redirects the data path through itself getting an easy access to all the data being transferred. Such nodes are called as malicious nodes.