The correct answer is that the IAM policy explicitly restricts the resource to a specific DB instance ARN in us-east-1, and the command specifies a different region. This fails because IAM resource restrictions are evaluated based on the ARN of the resource being accessed; when you run `aws rds describe-db-instances --region us-west-2`, the API call targets resources in that region, but the policy’s Allow statement only grants access to an ARN containing us-east-1, creating a region mismatch that denies the request. On the AWS Certified Database Specialty DBS-C01 exam, this tests your understanding of how IAM policy resource elements interact with regional endpoints—a common trap is assuming that a wildcard resource in a separate statement overrides an explicit ARN restriction, but IAM evaluates all statements and the explicit resource limitation effectively blocks cross-region access. A quick memory tip: “Explicit ARN locks the region, so a different region gets a denial.”
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 database administrator has the IAM policy shown above attached to their user. When they try to run the AWS CLI command `aws rds describe-db-instances --region us-west-2`, they receive an access denied error. Why does this fail?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The policy explicitly restricts the resource to a specific DB instance ARN in us-east-1, and the command specifies a different region.
Option B is correct. The resource statement in the first Allow explicitly limits access to the specific DB instance ARN in us-east-1. The second Allow allows rds:DescribeDBInstances on any resource, but the explicit resource restriction in the first statement does not grant access to resources in other regions. Since the command specifies us-west-2, the instance is not in that region, and the policy does not allow DescribeDBInstances on any resource in us-west-2. Option A is wrong because DescribeDBInstances is allowed on the specific resource, but not in us-west-2. Option C is wrong because there is no condition. Option D is wrong because the policy does not require MFA.
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.
✗
The user must use multi-factor authentication (MFA) to perform the describe action.
The user does not have permission to describe DB instances in any region.
Why it's wrong here
The policy allows DescribeDBInstances on the specific instance in us-east-1.
✗
The policy includes a condition key that denies access when the region is not us-east-1.
Why it's wrong here
No condition is present.
✓
The policy explicitly restricts the resource to a specific DB instance ARN in us-east-1, and the command specifies a different region.
Why this is correct
The resource ARN includes region us-east-1, so it does not apply to us-west-2.
Related concept
Read the scenario before looking for a memorised answer.
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.
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.
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: The policy explicitly restricts the resource to a specific DB instance ARN in us-east-1, and the command specifies a different region. — Option B is correct. The resource statement in the first Allow explicitly limits access to the specific DB instance ARN in us-east-1. The second Allow allows rds:DescribeDBInstances on any resource, but the explicit resource restriction in the first statement does not grant access to resources in other regions. Since the command specifies us-west-2, the instance is not in that region, and the policy does not allow DescribeDBInstances on any resource in us-west-2. Option A is wrong because DescribeDBInstances is allowed on the specific resource, but not in us-west-2. Option C is wrong because there is no condition. Option D is wrong because the policy does not require MFA.
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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