What is a Distributed Denial of Service (DDoS) attack?

A Distributed Denial of Service (DDoS) attack is defined as an attempt to make an online service unavailable by overwhelming it with traffic from multiple sources. In this type of attack, the perpetrator exploits a network of compromised systems, often referred to as a botnet, to flood the target service or network with an excessive amount of requests. This influx of traffic can overwhelm the system's capacity, making it unable to respond to legitimate requests, effectively denying access to genuine users.

Understanding this type of attack is crucial, as it can severely disrupt service availability and impact businesses, organizations, and individuals relying on the affected services. The other options do not accurately describe a DDoS attack. For example, enhancing server performance relates to optimization practices that aim to improve efficiency rather than disrupt it. Data encryption focuses on securing data to prevent unauthorized access, and network monitoring involves keeping track of network performance and security, which are all unrelated to the concept of flooding a service with unwanted traffic to deny access to legitimate users.