Which of the following indicates a security incident that requires attention?

Unusual network traffic is a strong indicator of a potential security incident that requires immediate attention. Such irregularities can suggest various malicious activities, including unauthorized access attempts, data breaches, or distributed denial-of-service (DDoS) attacks. By monitoring network traffic, organizations can identify suspicious patterns, such as unexpected spikes in data flow or communication from unfamiliar IP addresses, allowing them to take proactive measures to mitigate threats.

In contrast, software updates are a necessary part of maintaining system security but do not in themselves indicate a security incident. Regular maintenance schedules are essential for ensuring that systems remain functional and secure, but they are routine tasks and do not signify an immediate threat. Standard user complaints, while important for maintaining service quality, do not inherently indicate a security issue and often pertain to usability or technical problems unrelated to security incidents. Therefore, unusual network traffic stands out as a clear signal that something may be amiss and warrants further investigation.