Networks are becoming larger and a lot of advanced, yet directors think about various tools like ping and traceroute to correct issues. Instead of using different tools to debug the network problems, they introduced an automatic and systematic scheme for testing and debugging networks known as Automatic Test Packet Generation (ATPG). This automated approach fetches router configurations to generate a device independent model. The model is employed to get a minimum set of test packets to analyses each link in the network. The detected failures trigger a separate mechanism to localize the fault by sporadically sending test packets.