This DBS-C01 practice question tests your understanding of database security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: explicit Deny. 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.
The user can delete any database except 'prod-db'.
Why wrong: Incorrect. The user cannot delete any database because there is no allow for DeleteDBInstance. The explicit deny on 'prod-db' is redundant but does not grant delete on other databases.
B
The user can describe all databases except 'prod-db'.
Why wrong: Incorrect. The user can describe all databases, including 'prod-db', because DescribeDBInstances is allowed on all resources.
C
The user can modify 'prod-db' but cannot delete it.
Correct. The user can modify all databases because ModifyDBInstance is allowed, but cannot delete 'prod-db' due to the explicit deny. For other databases, deletion is also denied implicitly.
D
The user can modify any database except 'prod-db'.
Why wrong: Incorrect. The user can modify 'prod-db' as ModifyDBInstance is allowed on all resources, not excluded.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The user can modify 'prod-db' but cannot delete it.
The correct answer is C. The IAM policy allows DescribeDBInstances and ModifyDBInstance on all resources, but explicitly denies DeleteDBInstance on the database 'prod-db'. Since an explicit deny overrides any allow, the user cannot delete 'prod-db'. However, the policy does not allow DeleteDBInstance on any database, so the user cannot delete any database. For 'prod-db', the user can still modify and describe it because the deny is only for the delete action. Thus, the user can modify 'prod-db' but cannot delete it.
Key principle: Explicit Deny
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 can delete any database except 'prod-db'.
Why it's wrong here
Incorrect. The user cannot delete any database because there is no allow for DeleteDBInstance. The explicit deny on 'prod-db' is redundant but does not grant delete on other databases.
✗
The user can describe all databases except 'prod-db'.
Why it's wrong here
Incorrect. The user can describe all databases, including 'prod-db', because DescribeDBInstances is allowed on all resources.
✓
The user can modify 'prod-db' but cannot delete it.
Why this is correct
Correct. The user can modify all databases because ModifyDBInstance is allowed, but cannot delete 'prod-db' due to the explicit deny. For other databases, deletion is also denied implicitly.
Related concept
Explicit Deny
✗
The user can modify any database except 'prod-db'.
Why it's wrong here
Incorrect. The user can modify 'prod-db' as ModifyDBInstance is allowed on all resources, not excluded.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap is that the explicit deny on DeleteDBInstance for 'prod-db' might be misinterpreted as also blocking ModifyDBInstance for that database, but it only affects the delete action.
Detailed technical explanation
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Explicit Deny
Implicit Deny
IAM Policy Evaluation
Resource-Level Permissions
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
Explicit Deny
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.
Review explicit Deny, then practise related DBS-C01 questions on the same topic to reinforce the concept.
The correct answer is: The user can modify 'prod-db' but cannot delete it. — The correct answer is C. The IAM policy allows DescribeDBInstances and ModifyDBInstance on all resources, but explicitly denies DeleteDBInstance on the database 'prod-db'. Since an explicit deny overrides any allow, the user cannot delete 'prod-db'. However, the policy does not allow DeleteDBInstance on any database, so the user cannot delete any database. For 'prod-db', the user can still modify and describe it because the deny is only for the delete action. Thus, the user can modify 'prod-db' but cannot delete it.
What should I do if I get this DBS-C01 question wrong?
Review explicit Deny, then practise related DBS-C01 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Explicit Deny
About these practice questions
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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. Refer to the exhibit. An IAM policy is attached to a user. What is the effect when the user attempts to delete the RDS DB instance named 'prod-db'?
medium
A.The user can delete any other instance except 'prod-db'.
B.The user can delete the instance because the Deny statement only applies to snapshots.
✓ C.The user cannot delete the instance because of the explicit Deny statement.
D.The user can delete the instance because of the Allow on DescribeDBInstances.
Why C: The policy explicitly denies the rds:DeleteDBInstance action on the specific resource. Even though there is an Allow on other actions, an explicit Deny overrides any Allow. The user cannot delete the instance. Option A is wrong because the Deny takes precedence. Option B is wrong because the policy explicitly prevents deletion. Option D is wrong because the Deny is on the specific instance.
Variation 2. An IAM policy is attached to a user. What is the effect of this policy on the user's ability to delete the DB instance named prod-db?
hard
A.The user can delete the DB instance only after creating a final snapshot.
B.The user can delete the DB instance because the Allow statement grants all actions.
✓ C.The user cannot delete the DB instance because the Deny statement explicitly denies it.
D.The user can delete the DB instance because the Allow statement is broader and applies to all resources.
Why C: The question does not include the IAM policy text. Without the policy, it is impossible to determine whether there is an explicit Deny or Allow that affects the ability to delete the DB instance. Therefore, none of the provided options can be confirmed as correct based on the information given.
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Question Discussion
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