CS0-003 Incident Response and Management Practice Question
During a post-incident review, the incident response team identifies that the mean time to detect (MTTD) for a recent breach was 14 days, while the mean time to respond (MTTR) was 6 hours. Which metric should the team prioritize to improve in future incidents?
⚠ Common exam trap
CS0-004 often tests whether candidates reflexively pick 'improve MTTR' as the security answer without comparing the relative magnitudes of the two metrics — here 14 days vs. 6 hours makes detection the obvious priority.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Mean time to detect (MTTD)
With MTTD at 14 days and MTTR at only 6 hours, detection is clearly the bottleneck — attackers had nearly two weeks of dwell time before anyone noticed. Improving MTTD (via better logging, EDR tuning, threat hunting, or SIEM correlation) will reduce attacker dwell time and blast radius far more than shaving hours off an already-fast response.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Percentage of incidents containing malware
Why it's wrong here
This metric serves as a classification or categorization data point that helps security teams understand the threat landscape and vector prevalence. However, it does not measure the operational efficiency, speed, or performance of the incident response lifecycle. Tracking the proportion of malware-related events does nothing to help the team identify or contain threats faster.
- ✗
Number of incidents per week
Why it's wrong here
Measuring the weekly volume of incidents is useful for capacity planning, resource allocation, and identifying macro-level threat trends. However, this metric is purely quantitative and does not reflect the velocity or effectiveness of the security operations center (SOC). It fails to provide insight into how quickly analysts are identifying compromises once they occur.
- ✗
Mean time to respond (MTTR)
Why it's wrong here
Mean time to respond (MTTR) tracks the speed of containment, eradication, and recovery once an incident has been declared. While a critical metric, if the organization's MTTR is already low, focusing on further response acceleration yields diminishing returns. The primary bottleneck lies in the initial visibility phase, making response metrics less critical to optimize than detection metrics in this scenario.
- ✓
Mean time to detect (MTTD)
Why this is correct
Mean time to detect (MTTD) measures the duration between the initial security compromise and the moment security analysts identify the threat. Minimizing this metric is crucial because reducing dwell time directly limits an attacker's lateral movement and data exfiltration opportunities. By prioritizing MTTD, the organization can initiate containment protocols much earlier in the attack lifecycle, significantly mitigating overall business impact.
Quick reference
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
Go deeper
Related to this question
Learn chapter
Incident Response Process
Key term
Threat
A threat is any potential danger that could harm a computer system, network, or data, whether from a malicious hacker, a natural disaster, or an accidental mistake.
Key term
Detection
Detection is the process of identifying potential security incidents or anomalies by analyzing system data, logs, and network traffic.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This CS0-004 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CS0-004 exam.