From the thesis abstract: "DDoS [Distributed Denial of Service Attacks] attack is evolving at a rapid and alarming rate; an effective solution must be formulated using an adaptive approach. Most of the simulations are performed at the attack phase of the DDoS attack; thus the defense techniques developed focus mainly on filtering and isolating the attack. In order to develop and verify the effectiveness of a defense strategy, we needed a robust and flexible simulation tool. The Multi-Agent System Development Kit (MASDK) provided us a means to generate DDoS attack in a safe experimental environment for testing and validating security solutions, starting from the implantation phase: this allows researchers to develop new defense strategy even before the DDoS attack is launched. The paper begins with the study of the characteristics of DDoS attacks, the types of detection-and-response techniques, and the available DDoS attack simulation tools. The result generated by the MASDK simulation tool was used to evaluate the performance of the tool in simulating the DDoS attack over the networking environment."