CLF-C02 Security and Compliance Practice Question
A security team needs to analyze VPC network traffic to detect anomalies and investigate security incidents. Which AWS service captures and stores network flow data for VPCs?
⚠ Common exam trap
Many exam-takers confuse VPC Flow Logs (network traffic metadata) with AWS CloudTrail (API activity logs), often selecting CloudTrail because both involve logging, but CloudTrail does not capture network-level flow data.
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
✓
VPC Flow Logs
VPC Flow Logs capture IP traffic information for network interfaces within a VPC, including metadata such as source/destination IPs, ports, protocols, and packet accept/reject decisions. This data is stored in Amazon CloudWatch Logs or Amazon S3, enabling security teams to analyze traffic patterns, detect anomalies, and investigate incidents. AWS CloudTrail, Amazon Inspector, and Amazon GuardDuty serve different purposes—auditing API calls, assessing vulnerabilities, and threat detection, respectively—but do not directly capture raw network flow data.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS CloudTrail
Why it's wrong here
AWS CloudTrail records a history of AWS API calls and account-level activity across your infrastructure, capturing details like the identity of the caller, the API invoked, and the timestamp. These events relate to management actions (control plane), not to the data plane traffic that moves between your VPC resources. Consequently, CloudTrail is useful for auditing administrative changes but is not designed to capture or store network flow data.
- ✓
VPC Flow Logs
Why this is correct
VPC Flow Logs capture detailed metadata about the network traffic flowing through your VPC, including source and destination IP addresses, ports, protocol, packet and byte counts, and whether the traffic was accepted or rejected. Because this information is collected for every network interface, it provides the raw data needed for forensics, traffic analysis, and detecting anomalous behavior. Therefore, VPC Flow Logs is the service that directly captures and stores the flow data described in the question.
- ✗
Amazon Inspector
Why it's wrong here
Amazon Inspector is an automated vulnerability management service that continuously scans EC2 instances and container images for software vulnerabilities and unintentional network exposure. Its findings are based on periodic assessments and agent-based data collection, not on capturing live network traffic metadata. Therefore, while Inspector can highlight security risks, it does not provide the flow-level visibility needed to investigate actual traffic patterns between resources.
- ✗
Amazon GuardDuty
Why it's wrong here
Amazon GuardDuty is a continuous security monitoring service that uses machine learning and threat intelligence to detect malicious activity. It consumes VPC Flow Logs, DNS logs, and other data sources as inputs, but it does not originate or store the underlying network traffic records. Thus, GuardDuty can alert on anomalies in flow data, but it cannot serve as the service that captures and retains the flow metadata itself.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CLF-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 CLF-C02 exam.