What is a distributed denial-of-service (DDoS) attack?

A distributed denial-of-service (DDoS) attack is best defined as a coordinated attack that floods a target system with excessive requests from multiple sources. This method leverages numerous compromised devices or botnets to overwhelm the target, making it difficult or impossible for legitimate users to access the service. The fundamental concept behind DDoS attacks is to exhaust the resources of the target, whether it be bandwidth, processing power, or memory, leading to service degradation or complete unavailability.

The other options do not capture the essence of a DDoS attack. A breach of a single computer system refers to an unauthorized access event targeting one system specifically, which lacks the distributed nature of a DDoS. An internal network overload implies issues arising from within an organization's own network, rather than attacks originating from external sources. A cyber attack focused on encrypting files describes a ransomware incident, which is distinctly different in aim and methodology compared to a DDoS attack. The unique aspect of a DDoS attack lies in its distributed approach and the simultaneous nature of requests that overwhelm the target from multiple points.