Quick Answer
The answer is VPC Flow Logs, as this is the only AWS service designed to capture metadata about network traffic at the VPC, subnet, or elastic network interface level, including traffic between EC2 instances within the same subnet. VPC Flow Logs record IP traffic information such as source and destination addresses, ports, protocols, and packet accept/reject decisions, enabling comprehensive network monitoring without requiring any changes to the underlying infrastructure. On the AWS Certified Security Specialty SCS-C02 exam, this question tests your ability to distinguish between services that log network traffic versus those that log API activity or configuration changes—a common trap is confusing CloudTrail (API calls) or GuardDuty (threat detection) with actual traffic logging. Remember the memory tip: Flow Logs = Flowing packets; CloudTrail = Calls to the cloud; GuardDuty = Guarding against threats.
This SCS-C02 practice question tests your understanding of infrastructure security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
A company has a requirement to log all network traffic flowing through a VPC, including traffic between EC2 instances within the same subnet. Which AWS service should be used?
VPC Flow Logs
VPC Flow Logs capture IP traffic information.
Amazon GuardDuty
Why wrong: GuardDuty uses flow logs for threat detection but does not log traffic itself.
AWS Config
Why wrong: AWS Config records resource configurations.
AWS CloudTrail
Why wrong: CloudTrail logs API calls, not network traffic.
Answer choices
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
Option C is correct because VPC Flow Logs capture network traffic information at the VPC, subnet, or ENI level. Option A is wrong because CloudTrail logs API calls, not network traffic. Option B is wrong because AWS Config records resource configuration changes. Option D is wrong because GuardDuty is a threat detection service that uses flow logs but does not log traffic itself.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
VPC Flow Logs
Why this is correct
VPC Flow Logs capture IP traffic information.
Related concept
CIDR notation defines the prefix length.
Amazon GuardDuty
Why it's wrong here
GuardDuty uses flow logs for threat detection but does not log traffic itself.
AWS Config
Why it's wrong here
AWS Config records resource configurations.
AWS CloudTrail
Why it's wrong here
CloudTrail logs API calls, not network traffic.
Common exam traps
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Infrastructure Security — study guide chapter
Learn the concepts, then practise the questions
Infrastructure Security practice questions
Targeted practice on this topic area only
All SCS-C02 questions
1,738 questions across all exam domains
AWS Certified Security Specialty SCS-C02 study guide
Full concept coverage aligned to exam objectives
SCS-C02 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise SCS-C02 questions linked to Threat Detection and Incident Response.
Practise SCS-C02 questions linked to Security Logging and Monitoring.
Practise SCS-C02 questions linked to Identity and Access Management.
Practise SCS-C02 questions linked to Management and Security Governance.
Practise SCS-C02 questions linked to Infrastructure Security.
Practise SCS-C02 questions linked to Data Protection.
Practise SCS-C02 questions linked to SCS-C02 fundamentals.
Practise SCS-C02 questions linked to SCS-C02 scenario.
Practise SCS-C02 questions linked to SCS-C02 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Infrastructure Security — This question tests Infrastructure Security — CIDR notation defines the prefix length..
The correct answer is: VPC Flow Logs — Option C is correct because VPC Flow Logs capture network traffic information at the VPC, subnet, or ENI level. Option A is wrong because CloudTrail logs API calls, not network traffic. Option B is wrong because AWS Config records resource configuration changes. Option D is wrong because GuardDuty is a threat detection service that uses flow logs but does not log traffic itself.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
CIDR notation defines the prefix length.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 20, 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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.