What is a likely cause for the DoS issue experienced by the system administrator?

High CPU utilization by specific processes is a likely cause for a Denial of Service (DoS) issue because when the CPU is overwhelmed with processing demands, it may struggle to respond to legitimate requests. A system under high CPU stress may become unresponsive, significantly increasing response times or not responding at all, effectively denying service to users or applications that are trying to access the system.

In contrast, while external network configuration errors, power failures, and excessive memory usage could lead to service disruptions, they do not directly relate to a CPU’s processing capability in the same way. Network errors could affect connectivity but wouldn't necessarily signal a CPU-bound scenario. A power failure would interrupt all services abruptly, which is more catastrophic than the gradual service degradation that high CPU utilization would cause. Lastly, excessive memory usage could lead to swapping or paging that impairs performance, but it wouldn't target the CPU’s load directly or cause it to be taxed beyond its limits. Therefore, the pressure on CPU resources aligns closely with the symptoms of a DoS condition.