Earlier, we have proposed an automated model to minimise DDoS attacks in single ISP domain and extended the model to multiple ISP domains. Our approach has several advanced features to minimise DDoS attacks in the internet. The focus of this paper is twofold: firstly, to present a detailed description of the design and implementation of the proposed model and second to discuss and analyse the extensive set of results obtained from the implementation and simulations. We describe the prototype implementation of our automated model using NetProwler network intrusion detection system and HP OpenView Network Node Manager. We will also discuss the performance analysis of our model on a large scale using NS2 tool. Both prototype and simulation test results confirm that our approach offers a promising solution against DDoS problem in the internet and the model can be implemented in real time with minor modifications to the existing tools.