How does a denial-of-service (DoS) attack differ from a distributed denial-of-service (DDoS) attack?

A denial-of-service (DoS) attack occurs when a single attacker disrupts the services of a host or network by overwhelming it with a flood of illegitimate requests, which leads to a service becoming inaccessible to legitimate users. On the other hand, a distributed denial-of-service (DDoS) attack involves multiple systems working together to flood a target with a massive volume of traffic, making it even more difficult to defend against and causing significantly greater disruption due to the higher volume of attack traffic. Scope-wise, a DoS attack typically targets a single service or system, while a DDoS attack can target multiple services concurrently or focus on a larger network infrastructure. In terms of impact, DDoS attacks are usually more severe, as they can result in complete downtime for online services and lead to significant financial losses and reputation damage for the target.