The answer is that the policy fails because the Deny statement with `ForAllValues:StringNotEquals` does not block retrieval of all attributes when no `ProjectionExpression` is specified. This occurs because the condition only evaluates attributes explicitly requested; if a `GetItem` or `Query` call omits a `ProjectionExpression`, the request effectively asks for every attribute, and since no values are passed for comparison, the condition evaluates to true, meaning the Deny does not apply. On the AWS Certified Database Specialty DBS-C01 exam, this tests your understanding of how DynamoDB’s fine-grained access control interacts with attribute-level restrictions—a common trap is assuming a Deny on specific attributes automatically blocks full-item reads. Remember that `ForAllValues:StringNotEquals` acts like a filter on what is requested, not a blanket block on unrequested attributes. Memory tip: “No projection, no protection”—if you don’t specify attributes, the Deny won’t protect you.
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.
Refer to the exhibit. A DynamoDB table has a primary key of pk (partition key) and sk (sort key). An application needs to perform GetItem and Query operations but should only be allowed to retrieve the pk and sk attributes. The IAM policy above is applied to the application's IAM role. Why does the policy fail to achieve the goal?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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 does not prevent retrieval of all attributes when no ProjectionExpression is specified.
The Deny statement with the condition ForAllValues:StringNotEquals will deny a request if ANY requested attribute is not in the specified list. However, GetItem and Query can request specific attributes using ProjectionExpression. If the request does not specify any attributes, the condition evaluates to true (since no values to compare), and the Deny does not apply, allowing full item retrieval. Also, the condition uses StringNotEquals incorrectly; it should use StringEquals. The correct approach is to use a condition on dynamodb:Select or use a fine-grained access control with a condition on the requested attributes.
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 uses the wrong condition key; it should use 'dynamodb:Select' instead of 'dynamodb:Attributes'.
Why it's wrong here
While 'dynamodb:Select' is valid, the core issue is with 'ForAllValues:StringNotEquals' behavior.
✗
The policy should use 'dynamodb:ReturnValues' condition key.
Why it's wrong here
ReturnValues is for write operations like UpdateItem, not relevant here.
✓
The Deny statement does not prevent retrieval of all attributes when no ProjectionExpression is specified.
Why this is correct
If the request does not specify attributes, the condition has no values to compare, so the Deny is not applied, allowing full access.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
✗
The Allow statement should include 'dynamodb:Scan' to allow Query operations.
Why it's wrong here
Query does not require Scan permission; the Allow already includes Query.
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 Deny statement does not prevent retrieval of all attributes when no ProjectionExpression is specified. — The Deny statement with the condition ForAllValues:StringNotEquals will deny a request if ANY requested attribute is not in the specified list. However, GetItem and Query can request specific attributes using ProjectionExpression. If the request does not specify any attributes, the condition evaluates to true (since no values to compare), and the Deny does not apply, allowing full item retrieval. Also, the condition uses StringNotEquals incorrectly; it should use StringEquals. The correct approach is to use a condition on dynamodb:Select or use a fine-grained access control with a condition on the requested attributes.
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.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Standard ACLs match source addresses.
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