SCS-C02 Threat Detection and Incident Response Practice Question
A security team wants to detect unauthorized API calls in real time and automatically block the source IP address using network ACLs. Which AWS service should be used for detection?
⚠ Common exam trap
Watch out — candidates often confuse AWS CloudTrail's logging capability with real-time threat detection, overlooking that GuardDuty is specifically designed for proactive security monitoring and automated response, while CloudTrail is purely a logging and auditing service.
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
✓
Amazon GuardDuty
Amazon GuardDuty is the correct choice because it is a threat detection service that continuously monitors for malicious activity and unauthorized behavior, including API calls from unusual or known-bad IP addresses. It uses machine learning, anomaly detection, and integrated threat intelligence to generate findings that can trigger automated remediation, such as updating network ACLs via AWS Lambda and Amazon EventBridge. This aligns with the requirement for real-time detection and automated blocking of source IPs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Amazon GuardDuty
Why this is correct
Amazon GuardDuty continuously analyses CloudTrail management events, VPC Flow Logs and DNS logs using threat intelligence to surface findings such as unauthorised API calls. It satisfies the real-time detection constraint, and its findings can trigger EventBridge rules that invoke Lambda to update network ACLs, delivering the automated IP blocking the team requires.
- ✗
AWS CloudTrail
Why it's wrong here
AWS CloudTrail logs API activity for auditing and can deliver events to CloudWatch Events for real-time detection, but it does not itself block source IPs. It is tempting because it records every API call, and it would be correct for investigating who deleted a resource or triggered a specific action.
- ✗
AWS WAF
Why it's wrong here
AWS WAF filters HTTP(S) requests at the application layer against web ACL rules; it cannot detect unauthorised API calls across services nor trigger network ACL updates. It is tempting because it blocks malicious traffic, and it would be correct for filtering SQL injection or bot requests to a public web application.
- ✗
AWS Config
Why it's wrong here
AWS Config records resource configuration changes and evaluates compliance against rules; it does not capture API call activity in real time. It is tempting because it tracks account changes, and it would be correct for detecting whether an S3 bucket has become publicly readable or a security group has drifted.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SCS-C02 practice question is part of Courseiva's free Amazon Web Services 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 SCS-C02 exam.