What commonly accompanies a Denial of Service attack?

A Denial of Service (DoS) attack is characterized by an overwhelming demand on a network's resources, which can leave legitimate users unable to access services. Resource exhaustion is the process where system resources—such as bandwidth, memory, or CPU time—are consumed to the point where the system cannot respond to legitimate requests. This is typically what happens during a DoS attack, specifically when a malicious actor sends excessive traffic or requests to a target system, greatly outpacing its capacity to handle such requests.

In the context of the provided options, resource exhaustion directly correlates with the tactics employed in DoS attacks and represents the essence of the attack's goal: to render the system unusable by consuming its are limited resources. Other options, while they relate to network security and operational practices, do not specifically characterize or accompany a DoS attack. Enhanced firewall protection may help in mitigating attacks, increased data encryption is unrelated to the service availability, and regular system backups, while essential for recovery, do not relate to the immediate effects or objectives of a DoS attack. Thus, resource exhaustion stands out as the most relevant and defining aspect accompanying such attacks.