Which of the following typically represents a sign of a DDoS attack?

The choice indicating unusual spikes in network traffic leading to service disruption is indeed a strong indicator of a DDoS (Distributed Denial of Service) attack. During a DDoS attack, multiple compromised systems are used to flood a targeted server, service, or network with an overwhelming amount of traffic, causing legitimate requests to be denied or significantly delayed. This surge in traffic can lead to network congestion and, as a result, the affected services become unavailable to users.

In contrast, fast loading websites would not signify a DDoS attack, as they indicate normal performance. Increased security alerts from antivirus software may suggest other types of security threats but are not specifically indicative of a DDoS attack. Finally, regular server performance metrics would show standard operating conditions rather than the sudden and abnormal patterns often associated with DDoS attacks, thus reinforcing the notion that option B is the most accurate choice in this context.