AbstractMobile Ad hoc NETwork (MANET) is an infrastructure independent network with every mobile node acting as the router in the network formation. These networks are most useful when the present infrastructure is destroyed or at remote locations which are deprived of these amenities. One of the biggest challenges of these networks is the security of the data being sent and that is the main objective of our work. In this paper, security of the routing information is of the maximum priority. Zone Routing Protocol (ZRP), a hybrid MANET protocol is being implemented in Network Simulator 2 (NS2) and a hashing algorithm, keyed-Hash Message Authentication Code – Secure Hashing Algorithm 256 (HMAC-SHA256) is implemented for the Authentication and Data Integrity of the information being sent. In addition to that a Trust-Based system is formulated for preventing the Denial-of-Services (DoS) Attacks. The first part of this paper introduces the HMAC-SHA256 for ensuring that the data packets are received by the destination only and in its original form but at the expense of the increased processing time at the source and the destination. The second part uses the Trust-Based system with those nodes that act maliciously being broadcasted in the network and isolated to render a higher throughput and packet delivery fraction but at the expense of the increased end to end delay.