Focusing on packet marking traceback technology in DDoS attack defense，a novel approach is proposed to represent three elementary defending implementations namely attack tree construction，attack path frequency detection and packet to path association as succinct recurrence relations based on divide-and-conquer strategy，which uses single packet in-band path identifiers for unique packet to path association while handles attack tree construction and attack path frequency detection as independent out-of-band processes. By testing and evaluating the network traffic and storage overhead on real-life Internet，the results show that this method realistically achieves single packet traceback guarantees with minimal overhead for a large number of victims under heavy traffic loads simultaneously.