The answer is that the Scan operation will fail because the explicit Deny on dynamodb:Scan overrides any Allow. In AWS IAM, an explicit Deny always takes precedence over an Allow, regardless of the order in which the policies are evaluated. This is a fundamental rule of IAM policy evaluation logic: by default, all requests are implicitly denied, an explicit Allow grants access, but an explicit Deny is a definitive block that cannot be overridden by any other permission. On the AWS Certified Database Specialty DBS-C01 exam, this concept frequently appears in scenarios involving DynamoDB access control, testing your understanding of how explicit Denies interact with resource-based or identity-based policies. A common trap is assuming that a broader Allow statement can bypass a specific Deny, but AWS’s explicit Deny is absolute. Remember the mnemonic: “Deny always wins—if it says no, the show won’t go.”
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Scan operation will fail because the explicit Deny on dynamodb:Scan overrides the Allow.
Option D is correct because the explicit Deny for dynamodb:Scan overrides any Allow. Option A is wrong because the Deny is explicit and not ambiguous. Option B is wrong because the policy explicitly denies Scan. Option C is wrong because the policy does not allow Scan; the explicit Deny applies.
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 Scan operation will succeed because the Deny is on all resources but the Allow is specific to the table.
Why it's wrong here
Deny applies to all resources including the table.
✗
The Scan operation will succeed because the policy allows other operations on the table.
Why it's wrong here
Explicit Deny overrides Allow.
✗
The Scan operation will fail because the policy does not explicitly allow Scan.
Why it's wrong here
Implicit Deny is not the only reason; there is an explicit Deny.
✓
The Scan operation will fail because the explicit Deny on dynamodb:Scan overrides the Allow.
Why this is correct
Explicit Deny always overrides Allow.
Related concept
Standard ACLs match source addresses.
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.
Workload-Specific Database Design — This question tests Workload-Specific Database Design — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The Scan operation will fail because the explicit Deny on dynamodb:Scan overrides the Allow. — Option D is correct because the explicit Deny for dynamodb:Scan overrides any Allow. Option A is wrong because the Deny is explicit and not ambiguous. Option B is wrong because the policy explicitly denies Scan. Option C is wrong because the policy does not allow Scan; the explicit Deny applies.
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.
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Question Discussion
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