This document discusses software defined networks (SDNs) and detecting distributed denial-of-service (DDoS) attacks in SDNs. It provides background on SDN architecture and how DDoS attacks work. The paper aims to address risks of DDoS attacks in SDNs and focuses on detection. It describes existing DDoS attack techniques and solutions. The document proposes using algorithms like TCM-KNN and DPTCM-KNN for detection of attacks in network traffic flows, and compares the two algorithms using parameters like packet length and response time.