Using many separate systems (endpoints) to attack one target is the defining characteristic of a Distributed Denial of Service (DDoS) attack. Mike Meyers' Lab Manual defines DDoS as: ''An attack on a computer or network device in which multiple computers send data and requests to the device in an attempt to overwhelm it so that it cannot perform normal operations.'' That description exactly matches the scenario: many endpoints are coordinated to flood one endpoint, preventing legitimate use.

This is different from an on-path (man-in-the-middle) attack, which intercepts traffic between two parties; SQL injection, which targets databases via malicious input; and brute-force attacks, which attempt repeated authentication guesses. The key clue is multiple endpoints working together, which implies distribution (often via botnets) and service disruption by volume. That is why the correct classification is Distributed Denial of Service (D).