The answer is that the Deny statement overrides the Allow statement, blocking all DynamoDB actions. This occurs because AWS IAM policy evaluation logic gives an explicit Deny absolute precedence over any Allow, regardless of the order in which the statements appear. Even if a specific action like PutItem is allowed, a separate Deny statement targeting all DynamoDB actions will immediately revoke that permission. On the AWS Certified Database Specialty DBS-C01 exam, this concept frequently appears in troubleshooting scenarios where a developer’s application fails to write to DynamoDB or RDS despite having an Allow statement—testing your understanding that Deny is the ultimate override. A common trap is assuming the most specific resource or action wins, but in IAM, Deny always trumps Allow. Remember the mnemonic: Deny Defeats All—once a Deny is in place, no Allow can rescue it.
DBS-C01 Monitoring and Troubleshooting Practice Question
This DBS-C01 practice question tests your understanding of monitoring and troubleshooting. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 developer is troubleshooting an application that is unable to write to a DynamoDB table. The above IAM policy is attached to the IAM role used by the application. What is the likely cause?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Deny statement overrides the Allow statement, blocking all DynamoDB actions.
Option B is correct because the Deny statement for all DynamoDB actions overrides the Allow for PutItem. Deny statements always take precedence. Option A is wrong because the table name is correct. Option C is wrong because the role is assumed. Option D is wrong because the user exists.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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 Deny statement overrides the Allow statement, blocking all DynamoDB actions.
Why this is correct
Correct. An explicit Deny overrides any Allow, so PutItem is blocked.
Related concept
Standard ACLs match source addresses.
✗
The table name in the Resource ARN is incorrect.
Why it's wrong here
Incorrect. The ARN appears correct.
✗
The IAM user does not exist.
Why it's wrong here
Incorrect. The policy is attached to a role, not a user.
✗
The role is not correctly assumed by the application.
Why it's wrong here
Incorrect. The role assumption is not indicated by the policy.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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 ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DBS-C01 ACL questions on filtering logic and placement.
Monitoring and Troubleshooting — This question tests Monitoring and Troubleshooting — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The Deny statement overrides the Allow statement, blocking all DynamoDB actions. — Option B is correct because the Deny statement for all DynamoDB actions overrides the Allow for PutItem. Deny statements always take precedence. Option A is wrong because the table name is correct. Option C is wrong because the role is assumed. Option D is wrong because the user exists.
What should I do if I get this DBS-C01 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DBS-C01 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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. The user reports that they cannot delete the production-db database. Which statement best explains the behavior?
hard
✓ A.An explicit Deny statement prevents the deletion of the production-db instance
B.The user needs additional permissions to delete any DB instance
C.The user does not have permission to describe DB instances
D.The user does not have permission to create a DB instance
Why A: Option C is correct because an explicit Deny overrides any Allow. The Deny statement specifically denies DeleteDBInstance on that resource. Option A is wrong because the policy allows CreateDBInstance. Option B is wrong because DescribeDBInstances is allowed. Option D is wrong because the Deny is explicitly on the production-db ARN.
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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.
Question Discussion
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