Quick Answer
The answer is Amazon GuardDuty and AWS CloudTrail, as these two services work together to detect anomalous API activity in an AWS account. GuardDuty is a threat detection service that continuously analyzes CloudTrail management and data events, along with VPC Flow Logs and DNS logs, using machine learning and anomaly detection to identify unusual API calls, such as a spike in failed authentication attempts or requests from an unexpected geographic location. CloudTrail itself provides the raw audit trail of all API activity, which GuardDuty consumes for its analysis, making both services essential for detecting anomalies. On the AWS Certified Security Specialty SCS-C02 exam, this pairing tests your understanding that GuardDuty is the detection engine while CloudTrail is the data source; a common trap is choosing only CloudTrail because it logs API calls, but it does not actively detect anomalies without GuardDuty’s analysis. Memory tip: think of CloudTrail as the camera recording every API action, and GuardDuty as the security guard watching the footage for suspicious moves.
This SCS-C02 practice question tests your understanding of threat detection and incident response. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which TWO AWS services can be used to detect anomalous API activity in an AWS account? (Choose two.)
Amazon GuardDuty
GuardDuty detects anomalous API activity using ML.
AWS CloudTrail
CloudTrail logs can be analyzed for anomalous patterns.
VPC Flow Logs
Why wrong: VPC Flow Logs capture network traffic, not API calls.
AWS Config
Why wrong: AWS Config tracks configuration changes.
Amazon Inspector
Why wrong: Amazon Inspector scans for vulnerabilities.
Answer choices
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 a threat detection service that continuously monitors for malicious or unauthorized behavior, including anomalous API activity. It uses machine learning, anomaly detection, and integrated threat intelligence to analyze AWS CloudTrail management and data events, VPC Flow Logs, and DNS logs. When GuardDuty detects unusual API calls, such as a spike in failed authentication attempts or API calls from an unusual geographic location, it generates a security finding. This makes GuardDuty a correct choice for detecting anomalous API activity.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Amazon GuardDuty
Why this is correct
GuardDuty detects anomalous API activity using ML.
Related concept
Read the scenario before looking for a memorised answer.
AWS CloudTrail
Why this is correct
CloudTrail logs can be analyzed for anomalous patterns.
Related concept
Read the scenario before looking for a memorised answer.
VPC Flow Logs
Why it's wrong here
VPC Flow Logs capture network traffic, not API calls.
AWS Config
Why it's wrong here
AWS Config tracks configuration changes.
Amazon Inspector
Why it's wrong here
Amazon Inspector scans for vulnerabilities.
Common exam traps
The trap here is that candidates often confuse AWS CloudTrail as a detection service, but CloudTrail is only the logging source that records API activity; it does not analyze or detect anomalies on its own—GuardDuty consumes those logs for detection.
Detailed technical explanation
GuardDuty's anomaly detection for API activity relies on a baseline model built from CloudTrail management events (e.g., CreateUser, DeleteBucket) and optionally S3 data events. It uses statistical modeling and unsupervised learning to identify deviations from normal patterns, such as a sudden increase in Deny authorization failures or API calls from a new IP range. A real-world scenario is detecting a compromised IAM key where an attacker makes API calls from a region the account has never used before; GuardDuty flags this as an 'UnauthorizedAccess:IAMUser/InstanceCredentialExfiltration' finding.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
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FAQ
Threat Detection and Incident Response — This question tests Threat Detection and Incident Response — Read the scenario before looking for a memorised answer..
The correct answer is: Amazon GuardDuty — Amazon GuardDuty is a threat detection service that continuously monitors for malicious or unauthorized behavior, including anomalous API activity. It uses machine learning, anomaly detection, and integrated threat intelligence to analyze AWS CloudTrail management and data events, VPC Flow Logs, and DNS logs. When GuardDuty detects unusual API calls, such as a spike in failed authentication attempts or API calls from an unusual geographic location, it generates a security finding. This makes GuardDuty a correct choice for detecting anomalous API activity.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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