MANET is a collection of wireless mobile nodes forming a network without using any existing infrastructure. There are various challenges that are faced in the ad hoc environment. These are mostly due to the lack of resources of these networks. The solutions for conventional networks are usually not sufficient to provide efficient ad ho cooperation's. The wireless nature of communication and lack of any security infrastructure raise several security problems. Enhanced Adaptive ACKnowledge (EAACK) one of the Intrusion Detection System (IDS) mechanism which increases the integrity IDS of using digital signature.