The correct answer is to set the DB instance to be not publicly accessible and place it in a private subnet. This configuration works because disabling the public accessibility flag ensures the RDS instance does not receive a public IP address, while a private subnet lacks a route to an internet gateway, effectively cutting off all direct inbound and outbound internet traffic. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of network isolation fundamentals—a common trap is assuming that simply disabling the public accessibility flag is enough, but without a private subnet, the instance could still be reachable via a NAT device or a misconfigured route table. Remember the two-part rule: no public IP plus no internet gateway route equals true isolation. A useful memory tip is “No IP, No IGW” — if either condition is missing, the database remains exposed.
SCS-C02 Infrastructure Security Practice Question
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 security engineer needs to ensure that an Amazon RDS database instance is not accessible from the internet. Which configuration step will achieve this?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set the DB instance to be not publicly accessible and place it in a private subnet.
Option C is correct because setting a DB instance to be not publicly accessible ensures that it does not receive a public IP address, and placing it in a private subnet (one without a route to an internet gateway) prevents any direct inbound or outbound traffic from the internet. This combination guarantees that the RDS instance is isolated from the public internet, aligning with the security requirement.
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.
✗
Deploy the DB instance in a multi-AZ configuration.
Why it's wrong here
Multi-AZ is for high availability, not accessibility.
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Set the DB instance to be publicly accessible and restrict security group inbound rules.
Set the DB instance to be not publicly accessible and place it in a private subnet.
Why this is correct
This prevents internet access.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use the default VPC security group for the DB instance.
Why it's wrong here
Default security group may allow inbound traffic from within VPC but not block internet.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume security group rules alone can fully control internet access, overlooking the critical distinction between public and private IP assignment and subnet routing that determines actual internet reachability.
Detailed technical explanation
How to think about this question
When an RDS instance is set to 'Publicly Accessible = No', AWS does not assign a public IP address to the instance, and the underlying network interface is placed in a VPC subnet that lacks an internet gateway route. Even if a security group inadvertently allows inbound traffic from 0.0.0.0/0, the absence of a public IP means the instance cannot be reached from the internet. In contrast, a 'Publicly Accessible = Yes' instance receives a public IP and is assigned to a public subnet, making it reachable via the internet gateway regardless of security group rules.
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: Set the DB instance to be not publicly accessible and place it in a private subnet. — Option C is correct because setting a DB instance to be not publicly accessible ensures that it does not receive a public IP address, and placing it in a private subnet (one without a route to an internet gateway) prevents any direct inbound or outbound traffic from the internet. This combination guarantees that the RDS instance is isolated from the public internet, aligning with the security requirement.
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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Question Discussion
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