In a Distributed Denial-of-Service (DDoS) attack, multiple systems usually infected with a Trojan are used to target a single system causing a Denial of Service (DoS) attack. Victims of a DDoS attack consist of both the end targeted system and all systems maliciously used and controlled by the hacker in the distributed attack. Unlike a Denial of Service (DoS) attack, which uses one Internet-connected device to flood a target with fake traffic, a DDoS attack uses multiple devices, often compromised by the attacker.