A SOC manager reviews a post-incident timeline showing that a web server was compromised at 02:14, but the SIEM correlation rule did not generate an alert until 09:40, when the overnight log batch was ingested and analyzed. Which metric BEST describes the roughly seven-and-a-half-hour gap the manager is measuring?
- A. Mean time to detect (MTTD) Correct
- B. Mean time to respond/remediate (MTTR)
- C. Mean time to acknowledge (MTTA)
- D. Service-level agreement (SLA) attainment rate
Why A is correct
MTTD measures the elapsed time from when a security event actually occurs to the moment the organization's monitoring capability identifies it. The gap described, from the 02:14 compromise to the 09:40 alert, is exactly what MTTD tracks. Shrinking MTTD is a core SOC efficiency goal, often achieved through faster log ingestion cadence, better-tuned correlation rules, and continuous monitoring rather than batch-based analysis.
Why the others are incorrect
Mean time to respond/remediate would measure the time from when response work begins until the incident is contained or eradicated, which has not even started yet in this scenario. Mean time to acknowledge measures the separate, later interval between the 09:40 alert firing and an analyst picking it up, not the detection gap itself. SLA attainment rate is a broader compliance percentage measured against a target over many incidents, not a single-incident duration between compromise and detection.