CLF-C02 Security and Compliance Practice Question
A security team suspects unauthorised network traffic is reaching a subnet in their VPC. They need to capture metadata about the IP traffic (source IP, destination IP, port, protocol, accept/reject status) flowing through their VPC network interfaces for analysis. Which AWS feature provides this network traffic metadata?
⚠ Common exam trap
Test-takers frequently confuse VPC Flow Logs with CloudTrail or GuardDuty, mistakenly thinking that CloudTrail captures network traffic or that GuardDuty generates the raw metadata, when in fact VPC Flow Logs are the only service that directly captures the specified network traffic metadata at the interface level.
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 metadata about IP traffic flowing through VPC network interfaces, including source/destination IP addresses, ports, protocol numbers, and accept/reject status (based on security group and NACL rules). This is the correct service because it is specifically designed to log network traffic metadata at the VPC, subnet, or network interface level, enabling security analysis without impacting network performance.
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 API activity in the AWS management plane, including who made a request, which service was called, the source IP of the caller, and any errors returned. It does not capture data-plane traffic such as packets moving between EC2 instances or through VPC subnets, so it is irrelevant for analyzing network traffic flows at the IP/port/protocol level within a VPC.
- ✗
Amazon GuardDuty
Why it's wrong here
Amazon GuardDuty is a threat detection service that relies on VPC Flow Logs, DNS request logs, and other telemetry as data sources; it does not directly capture or record network traffic metadata itself. Though it can surface findings from flow data, the raw network traffic analysis artifact is still VPC Flow Logs, making GuardDuty an analytics consumer, not the collection mechanism.
- ✓
VPC Flow Logs
Why this is correct
VPC Flow Logs capture IP traffic metadata for elastic network interfaces (ENIs) in a VPC, including source and destination IP/port, protocol, and whether the traffic was accepted or rejected by security groups and network ACLs. They can be published to Amazon CloudWatch Logs or Amazon S3 and can be created at the VPC, subnet, or ENI level, making them the direct, standard feature for analyzing VPC network traffic.
- ✗
AWS WAF logs
Why it's wrong here
AWS WAF logs record detailed information about HTTP/HTTPS requests that are evaluated by WAF web ACLs, such as request headers, URI, and the rule action taken. These logs apply only to resources protected by WAF—like CloudFront, Application Load Balancer, or API Gateway—so they do not capture general network-level IP traffic flowing through VPC network interfaces and cannot serve as a VPC-wide traffic analysis source.
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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.