The answer is to modify the security group to allow inbound traffic on port 3306 from the client IP. This is required because Amazon RDS instances are launched within a VPC and, by default, all inbound traffic is blocked at the security group level, which acts as a virtual firewall. Even if the RDS instance is publicly accessible with a public DNS endpoint, the security group must explicitly permit traffic on the MySQL port (3306) from the specific client IP address to establish a connection. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of network-level access controls versus authentication or DNS resolution—a common trap is confusing a public endpoint with open network access. Remember that a public DNS does not bypass security group rules; you must still open the port. Memory tip: "Port 3306 must be fixed, or the connection gets nixed."
DBS-C01 Deployment and Migration Practice Question
This DBS-C01 practice question tests your understanding of deployment and migration. 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.
Network Topology
Refer to the exhibit. A company is migrating from an on-premises MySQL database to Amazon RDS for MySQL. The DBA wants to connect to the RDS instance using the endpoint shown. What additional step is required to allow the DBA's client to connect?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Modify the security group to allow inbound traffic on port 3306 from the client IP
Option C is correct because by default, RDS instances do not allow inbound traffic; a security group must allow traffic on port 3306. Option A is wrong because the endpoint is already public if the instance is public. Option B is wrong because the user already exists. Option D is wrong because the DNS endpoint is already provided.
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 security group to allow inbound traffic on port 3306 from the client IP
Why this is correct
Security group rules control inbound traffic; port 3306 must be open.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create a Route 53 record for the endpoint
Why it's wrong here
The endpoint DNS is already provided; no additional Route 53 record is needed.
✗
Create a MySQL user that matches the client's IP
Why it's wrong here
A MySQL user is needed, but that is part of setup, not the connection issue.
✗
Change the RDS instance to be publicly accessible
Why it's wrong here
The instance may already be public; the endpoint is shown, but security group still needs to allow access.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Trap categories for this question
Command / output trap
The instance may already be public; the endpoint is shown, but security group still needs to allow access.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 DBS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Deployment and Migration — This question tests Deployment and Migration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Modify the security group to allow inbound traffic on port 3306 from the client IP — Option C is correct because by default, RDS instances do not allow inbound traffic; a security group must allow traffic on port 3306. Option A is wrong because the endpoint is already public if the instance is public. Option B is wrong because the user already exists. Option D is wrong because the DNS endpoint is already provided.
What should I do if I get this DBS-C01 question wrong?
Identify which DBS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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