Mobile ad-hoc networks are sel f-configuring networks of mobi le devices that can be establi shedrnwi thout a need for a network infrastructure. The faci that mobile ad-hoc networks lack centralrnadministrat ion and use wireless link for communication makes them very susceptible to variousrntypes of adversary's malicious attacks. Black hole attack is one of the severe security threats inrnad-hoc networks that can be eas ily performed by exploi ting vulnerability of on-demand routi ngrnprotocols s lIch as AODV. We implemented a solution to prevent black hole attac ks imposed byrnboth single and multiple black hole nodes. Intrusion Detection lIsing Anomaly Detectionrn(lOAD), works based on a general principle of Intrusion Detection Systems (IDS). It means anrnlOAD system identifies anomaly activities of an adversa ry from normalcy act ivities of nonmalicrnious mobile nodes. The identification process in volves comparing communication attributesrnof each mobile node part icipating in a given ad-hoc network. The most distinguishingrncharacteristic of lOAD is that it works in no-peer-t rust principle. Unlike the ex isti ng black holernattack prevention techniques that rely on the cooperation of mobile nodes to announce a presencernof intrusion, lOAD enab les each mobile node to protect itself from an intruder. Implcmentationrnof the prevention mechanism has been carried out by usin g the Network Simulation version 2rn(NS2). A Java Parser program and Tracegraph has also been used to analyze results ofrnsimulation. Post-analysis result proves the preven tion method implemcnted maxi mi zes networkrnperformance by effectively preventing black hole attacks again st mobi le ad-hoc networks as wetlrnus mini mi zing generation of control (routing) pac kets.