This research paper is proposing one monitoring application for Denial of Service (DoS) with use of group testing approach. Here a semi-Markov model anomaly detector will help to describe the dynamics of access matrix and to detect the attacks. The focus of this work lies in the detection algorithms proposed and the corresponding theoretical complexity analysis. We also provide preliminary simulation results regarding the efficiency and practicability of this new scheme. Further discussions over implementation issues and performance enhancements are also appended to show its great potentials. © 2014 IEEE.