An example of a DDoS attack would include which of the following?

A DDoS (Distributed Denial of Service) attack is characterized by overwhelming a target, such as a server or network, with a flood of traffic from multiple sources. This is typically achieved through the coordinated use of numerous compromised systems, which can be spread across various geographical locations.

The correct choice encapsulates this concept well, as it refers to a large number of transmissions coming from multiple external computers. This distributed aspect is crucial because it differentiates DDoS attacks from other forms of attacks that derive traffic from a single source or a limited number of systems.

In contrast, flooding with requests from a single user would not meet the criteria for a DDoS attack, as that would represent a DoS (Denial of Service) attack instead. Phishing emails and malicious software installed on local machines involve different attack vectors that focus more on deception or gaining unauthorized access rather than overwhelming a service with traffic. Understanding the nature of these threats is essential for recognizing and mitigating the potential impacts in a networked environment.