Distributed Denial of Service （DDoS） attacks， as a highly destructive type of cyber attacks， have become one of the most severe threats and challenges in the field of cybersecurity in recent years due to their low attack costs， high attack efficiency， and strong concealment. DDoS attacks employ a distributed control approach to mix malicious traffic with legitimate network requests， making it difficult for traditional security defense mechanisms such as Intrusion Detection System （IDS） and firewalls to identify and mitigate such attacks effectively. Consequently， the efficient detection and effective defense against DDoS attacks have become research hotspots and difficulties in the field of cybersecurity. Based on systematic survey of the existing research on DDoS attacks， the following was performed. Firstly， the classification methods of DDoS attacks were sorted out， and DDoS attacks were summed up from multiple perspectives， so as to provide a deeper understanding of DDoS attack mechanisms. Secondly， an analysis of the current development of DDoS attacks was conducted， with particular focuses on discussing the development trends in attack intensity， attack methods， and attack distribution， thereby providing support for the research on more efficient DDoS defense technologies. Thirdly， an in-depth analysis and evaluation of the status of DDoS attack defense technologies was conducted from both industrial and academic perspectives， which focused on DDoS detection and defense methods based on programmable switches and machine learning in the academic aspect， and compared and analyzed the defense architectures adopted by different participants in DDoS defense in the industrial aspect as well as summarized the technical characteristics， application scenarios， and the existing challenges of the architecture. Finally， based on a comprehensive analysis of the current DDoS attack situations， the future development directions， opportunities， and challenges of DDoS defense technology were prospected， providing new ideas and directions for researchers in the field of cybersecurity and promoting further innovation and development of DDoS defense technology.