This SCS-C02 practice question tests your understanding of infrastructure security. 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.
A security engineer is configuring a VPC for a new application. Which TWO actions will improve network security? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use network ACLs to allow or deny traffic at the subnet level.
Option C is correct because network ACLs (NACLs) operate at the subnet level as a stateless firewall, allowing you to explicitly allow or deny inbound and outbound traffic based on rules (e.g., source/destination IP, port, protocol). This provides a critical layer of defense at the subnet boundary, complementing security groups. Option E is correct because security groups act as a stateful virtual firewall at the instance (ENI) level, controlling traffic based on allow rules only, which is essential for granular per-instance security.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Configure VPC endpoints to connect to AWS services privately.
Why it's wrong here
VPC endpoints provide private connectivity, not filtering.
✗
Deploy a NAT gateway to allow outbound internet access.
Why it's wrong here
NATgateway enables outbound traffic, does not filter.
✓
Use network ACLs to allow or deny traffic at the subnet level.
Read the scenario before looking for a memorised answer.
✗
Enable VPC Flow Logs to analyze traffic patterns.
Why it's wrong here
Flow logs are for monitoring, not enforcement.
✓
Use security groups to control traffic at the instance level.
Why this is correct
Security groups are stateful firewalls for instances.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse detective controls (like VPC Flow Logs) or connectivity mechanisms (like NAT gateways or VPC endpoints) with direct security controls that enforce traffic filtering, leading them to select options that improve visibility or connectivity rather than security posture.
Detailed technical explanation
How to think about this question
Network ACLs are stateless, meaning you must define both inbound and outbound rules separately, and they are evaluated in numerical order (lowest to highest) with an implicit deny all rule at the end. Security groups are stateful, so if you allow inbound traffic on port 443, the outbound return traffic is automatically allowed regardless of outbound rules. In a real-world scenario, a common best practice is to use NACLs as a coarse-grained subnet-level filter (e.g., block known malicious IP ranges) and security groups for fine-grained instance-level control (e.g., allow only specific application ports).
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Infrastructure Security — This question tests Infrastructure Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use network ACLs to allow or deny traffic at the subnet level. — Option C is correct because network ACLs (NACLs) operate at the subnet level as a stateless firewall, allowing you to explicitly allow or deny inbound and outbound traffic based on rules (e.g., source/destination IP, port, protocol). This provides a critical layer of defense at the subnet boundary, complementing security groups. Option E is correct because security groups act as a stateful virtual firewall at the instance (ENI) level, controlling traffic based on allow rules only, which is essential for granular per-instance security.
What should I do if I get this SCS-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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
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