ITIL 4 Foundation Practice Exam

Which metric assesses how frequently a service fails?

1. Mean time to restore service (MTRS)

2. Service uptime measure

3. Mean time between failures (MTBF)

4. Customer satisfaction index

The correct answer is: Mean time between failures (MTBF)

The metric that assesses how frequently a service fails is the Mean Time Between Failures (MTBF). MTBF is a reliability metric that indicates the average time elapsed between one failure of a service and the next. By measuring this time, organizations can gauge how often failures occur in a service, which is crucial for understanding the overall reliability and performance of that service. A higher MTBF indicates that failures are infrequent, while a lower MTBF suggests that failures happen more regularly. In contrast, Mean Time to Restore Service (MTRS) focuses on the average time taken to recover from service failures, highlighting the efficiency of response and recovery efforts rather than the frequency of the failures themselves. The Service Uptime Measure reflects the percentage of time a service is operational and available to customers, which does not directly correlate with how often it fails. The Customer Satisfaction Index assesses how satisfied users are with the service but is unrelated to failure rates or frequency. Thus, MTBF stands out as the most appropriate metric for evaluating how frequently a service fails.