DBS-C01 Database Security Practice Question
A company is using Amazon RDS for MySQL and needs to restrict access to the database to only specific Amazon EC2 instances in the same VPC. Which security mechanism should be used?
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
✓
Configure a VPC security group that allows inbound traffic from the EC2 security groups.
In a VPC, RDS instances use VPC security groups to control inbound traffic. Configuring a VPC security group that allows inbound traffic from the EC2 security groups is the correct mechanism. Option B is incorrect because IAM policies control API access, not network connectivity. Option C is incorrect because subnet groups define subnets for deployment, not security rules. Option D is incorrect because network ACLs are stateless, apply to entire subnets, and cannot reference security groups or specific instances.
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 a VPC security group that allows inbound traffic from the EC2 security groups.
Why this is correct
DB security groups are only applicable in EC2-Classic, not in a VPC. In a VPC, you should use a VPC security group to control traffic to the RDS instance.
- ✗
Create an IAM policy that allows the EC2 instances to connect to the RDS instance.
Why it's wrong here
IAM policies govern permissions for AWS API calls (e.g., to create or modify RDS instances), not network-level access to the database.
- ✗
Create a DB subnet group that includes only the subnets where the EC2 instances reside.
Why it's wrong here
A DB subnet group determines which subnets an RDS instance can be deployed in; it does not provide inbound traffic control.
- ✗
Modify the network ACL for the DB subnet to allow traffic from the EC2 instances' IP addresses.
Why it's wrong here
Network ACLs are stateless, operate at the subnet level, and cannot be used to restrict access to specific instances. They also do not support referencing security groups.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-C01 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 DBS-C01 exam.