- A
Modify the inbound rule of 'app-sg' to allow HTTP traffic from the private IP addresses of the ALB nodes.
Why wrong: Incorrect: ALB node IPs are dynamic and managed by AWS; this approach is not scalable or reliable.
- B
Modify the inbound rule of 'app-sg' to allow HTTPS traffic from 0.0.0.0/0 and remove the HTTP rule.
Why wrong: Incorrect: This still allows traffic from anywhere, not just the ALB, and does not restrict source.
- C
Modify the inbound rule of 'app-sg' to allow HTTP traffic from the ALB's elastic network interface (ENI).
Why wrong: Incorrect: ENIs are not static and referencing them is not a best practice for security group rules.
- D
Modify the inbound rule of 'app-sg' to allow HTTP traffic from security group 'alb-sg'.
Correct: This restricts inbound traffic to only the ALB, as the ALB is associated with 'alb-sg'.
SCS-C02 Infrastructure Security Practice Question
This SCS-C02 practice question tests your understanding of infrastructure security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 runs a web application on EC2 instances in an Auto Scaling group across two Availability Zones. The instances are behind an Application Load Balancer. The security team wants to ensure that only the ALB can send traffic to the instances. The instances are in a security group named 'app-sg'. Currently, 'app-sg' has an inbound rule allowing HTTP traffic from 0.0.0.0/0. The team wants to restrict access to only the ALB's security group. The ALB is in a security group named 'alb-sg'. Which course of action should the security engineer take to meet the requirement with minimal disruption?
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
Modify the inbound rule of 'app-sg' to allow HTTP traffic from security group 'alb-sg'.
Option D is correct because security groups can reference each other by ID, allowing traffic from any instance associated with the source security group (alb-sg) without needing to know the ALB's IP addresses. This ensures that only the ALB can send HTTP traffic to the EC2 instances, as the rule dynamically applies to all ALB nodes across Availability Zones. It also minimizes disruption because no IP changes are required, and the rule automatically scales with the ALB.
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.
- ✗
Modify the inbound rule of 'app-sg' to allow HTTP traffic from the private IP addresses of the ALB nodes.
Why it's wrong here
Incorrect: ALB node IPs are dynamic and managed by AWS; this approach is not scalable or reliable.
- ✗
Modify the inbound rule of 'app-sg' to allow HTTPS traffic from 0.0.0.0/0 and remove the HTTP rule.
Why it's wrong here
Incorrect: This still allows traffic from anywhere, not just the ALB, and does not restrict source.
- ✗
Modify the inbound rule of 'app-sg' to allow HTTP traffic from the ALB's elastic network interface (ENI).
Why it's wrong here
Incorrect: ENIs are not static and referencing them is not a best practice for security group rules.
- ✓
Modify the inbound rule of 'app-sg' to allow HTTP traffic from security group 'alb-sg'.
Why this is correct
Correct: This restricts inbound traffic to only the ALB, as the ALB is associated with 'alb-sg'.
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 may think they need to use the ALB's private IP addresses or ENI details, but AWS security groups support referencing other security groups by ID, which is the correct and scalable method for this use case.
Detailed technical explanation
How to think about this question
Security group referencing works by allowing traffic from any instance or resource that is associated with the referenced security group, regardless of IP address changes. Under the hood, AWS maps the security group ID to the current private IPs of all attached ENIs, updating automatically as instances scale. In a real-world scenario, this is critical for multi-AZ deployments where ALB nodes have dynamic IPs, ensuring zero-trust network segmentation without manual intervention.
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 — 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
Related SCS-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Threat Detection and Incident Response practice questions
Practise SCS-C02 questions linked to Threat Detection and Incident Response.
Security Logging and Monitoring practice questions
Practise SCS-C02 questions linked to Security Logging and Monitoring.
Identity and Access Management practice questions
Practise SCS-C02 questions linked to Identity and Access Management.
Management and Security Governance practice questions
Practise SCS-C02 questions linked to Management and Security Governance.
Infrastructure Security practice questions
Practise SCS-C02 questions linked to Infrastructure Security.
Data Protection practice questions
Practise SCS-C02 questions linked to Data Protection.
SCS-C02 fundamentals practice questions
Practise SCS-C02 questions linked to SCS-C02 fundamentals.
SCS-C02 scenario practice questions
Practise SCS-C02 questions linked to SCS-C02 scenario.
SCS-C02 troubleshooting practice questions
Practise SCS-C02 questions linked to SCS-C02 troubleshooting.
Practice this exam
Start a free SCS-C02 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this SCS-C02 question test?
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: Modify the inbound rule of 'app-sg' to allow HTTP traffic from security group 'alb-sg'. — Option D is correct because security groups can reference each other by ID, allowing traffic from any instance associated with the source security group (alb-sg) without needing to know the ALB's IP addresses. This ensures that only the ALB can send HTTP traffic to the EC2 instances, as the rule dynamically applies to all ALB nodes across Availability Zones. It also minimizes disruption because no IP changes are required, and the rule automatically scales with the ALB.
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.
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 11, 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.