- A
Modify the network ACL for the DB subnet to allow inbound port 3306 from the EC2 instance's private IP.
Why wrong: Network ACLs are stateless and require separate inbound and outbound rules; security groups are more appropriate for this use case.
- B
Remove the inbound rule for 0.0.0.0/0 on the RDS security group.
Removing the overly permissive rule is necessary to restrict access.
- C
Add an inbound rule to the RDS security group referencing the security group ID of the EC2 instances.
Referencing the EC2 security group allows traffic only from instances using that security group, following best practices.
- D
Modify the DB subnet group to place the RDS instance in a public subnet with a route to the EC2 instance.
Why wrong: Placing the database in a public subnet is insecure and unnecessary; subnet group changes do not affect security group rules.
- E
Add an inbound rule to the RDS security group allowing traffic from the VPC CIDR on port 3306.
Why wrong: This would still allow any resource in the VPC, which is broader than needed.
Quick Answer
The correct answer is to remove the 0.0.0.0/0 rule and add an inbound rule referencing the security group ID of the EC2 instances. This works because security group referencing allows you to restrict RDS access by security group rather than by IP, enabling dynamic, stateful filtering that automatically adapts as EC2 instances are added or removed within the referenced group. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of VPC security group chaining for database access—a common trap is choosing IP-based rules, which break if instance IPs change or scale. Remember that within the same VPC, referencing a security group ID is more resilient and aligns with AWS best practices for least-privilege access. Memory tip: “Group the groups”—when restricting RDS access, think security group IDs, not IPs, for elastic, maintainable control.
DBS-C01 Database Security Practice Question
This DBS-C01 practice question tests your understanding of database 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 company runs an Amazon RDS for MySQL DB instance in a VPC. Security requirements mandate that only specific EC2 instances in the same VPC can connect to the database. The security group attached to the RDS instance currently allows inbound traffic on port 3306 from 0.0.0.0/0. Which combination of steps should a database specialist take to meet the security requirement without impacting existing application connectivity? (Choose two.)
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
Remove the inbound rule for 0.0.0.0/0 on the RDS security group.
Option B is correct because removing the overly permissive inbound rule for 0.0.0.0/0 on the RDS security group eliminates unrestricted access, which is a direct violation of the security requirement. Option C is correct because adding an inbound rule that references the security group ID of the EC2 instances allows traffic only from those instances, leveraging security group referencing for granular, stateful access control within the same VPC.
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 network ACL for the DB subnet to allow inbound port 3306 from the EC2 instance's private IP.
Why it's wrong here
Network ACLs are stateless and require separate inbound and outbound rules; security groups are more appropriate for this use case.
- ✓
Remove the inbound rule for 0.0.0.0/0 on the RDS security group.
Why this is correct
Removing the overly permissive rule is necessary to restrict access.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Add an inbound rule to the RDS security group referencing the security group ID of the EC2 instances.
Why this is correct
Referencing the EC2 security group allows traffic only from instances using that security group, following best practices.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Modify the DB subnet group to place the RDS instance in a public subnet with a route to the EC2 instance.
Why it's wrong here
Placing the database in a public subnet is insecure and unnecessary; subnet group changes do not affect security group rules.
- ✗
Add an inbound rule to the RDS security group allowing traffic from the VPC CIDR on port 3306.
Why it's wrong here
This would still allow any resource in the VPC, which is broader than needed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse network ACLs with security groups, thinking that modifying the NACL at the subnet level is sufficient, but they overlook that NACLs are stateless and less granular, while security group referencing provides precise, stateful control for instance-to-instance communication.
Detailed technical explanation
How to think about this question
Security group referencing works by allowing traffic based on the source security group's ID, which is resolved dynamically as instances are added or removed; this is more secure than using IP addresses because it automatically adapts to instance scaling and avoids the need for manual IP updates. Under the hood, AWS evaluates security group rules in a stateful manner, meaning that if inbound traffic is allowed from a security group, the corresponding outbound return traffic is automatically permitted, simplifying rule management. In a real-world scenario, this approach is critical for microservices architectures where EC2 instances may have dynamic private IPs due to auto-scaling, ensuring consistent database access without security gaps.
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.
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FAQ
Questions learners often ask
What does this DBS-C01 question test?
Database Security — This question tests Database Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Remove the inbound rule for 0.0.0.0/0 on the RDS security group. — Option B is correct because removing the overly permissive inbound rule for 0.0.0.0/0 on the RDS security group eliminates unrestricted access, which is a direct violation of the security requirement. Option C is correct because adding an inbound rule that references the security group ID of the EC2 instances allows traffic only from those instances, leveraging security group referencing for granular, stateful access control within the same VPC.
What should I do if I get this DBS-C01 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 →
Same concept, more angles
1 more ways this is tested on DBS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses Amazon RDS for PostgreSQL and needs to ensure that only specific IP addresses can connect to the database. Which configuration should be used?
medium- A.Configure the DB subnet group to allow only specific IP addresses.
- B.Set the rds.force_ssl parameter in the DB parameter group.
- C.Create an IAM policy that restricts access to the RDS API based on source IP.
- ✓ D.Modify the VPC security group associated with the DB instance to allow inbound traffic only from specific IP addresses.
Why D: Option C is correct because security group rules control inbound traffic based on IP addresses or other security groups. Option A is wrong because DB subnet groups define subnets, not IP filtering. Option B is wrong because parameter groups control database engine parameters, not network access. Option D is wrong because IAM policies control permissions for AWS actions, not network-level access.
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Last reviewed: Jun 11, 2026
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.
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