The answer is the ForAllValues:StringEquals condition set operator, which blocks Scan operations because it requires all leading keys to match a single value, an impossible condition for a Scan that reads across multiple partitions. The dynamodb:LeadingKeys IAM condition key is designed to restrict access to specific partition key values, but when combined with ForAllValues:StringEquals, it demands that every item in the request share the same leading key. Since a Scan operation does not specify a single partition key—it iterates over all items—the condition can never be satisfied, resulting in an AccessDeniedException. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of how IAM condition keys interact with DynamoDB operations, particularly the nuance that ForAllValues acts as a universal quantifier. A common trap is confusing it with ForAnyValue, which would allow a Scan if any item matched. Memory tip: think “ForAllValues = all items must match, Scan = all items, so they conflict.”
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.
Refer to the exhibit. An IAM policy is attached to a user who is attempting to run a Scan operation on the Orders table using the AWS CLI. The Scan operation fails with an AccessDeniedException. What is the most likely reason?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Why wrong: The ARN includes the table name 'Orders'.
B
The Scan action is not allowed in the policy.
Why wrong: Scan is listed in the Action array.
C
The condition requires the partition key to be 'CustomerID', but the Scan operation does not specify a partition key.
Why wrong: The condition 'LeadingKeys' applies to the partition key, but the issue is the use of 'ForAllValues'.
D
The 'ForAllValues:StringEquals' condition set operator prevents the Scan operation because it requires all leading keys to match a single value, which is impossible for a Scan.
'ForAllValues' evaluates to false if the request has no leading keys (as in Scan) or multiple keys.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The 'ForAllValues:StringEquals' condition set operator prevents the Scan operation because it requires all leading keys to match a single value, which is impossible for a Scan.
Option D is correct. The condition 'dynamodb:LeadingKeys' applies only to Query and Scan operations when the condition key is used to restrict partition key values. However, the condition 'ForAllValues:StringEquals' requires that all leading keys in the request match the specified value. For a Scan operation without a specific partition key, the condition cannot be satisfied, leading to denial. Option A is incorrect because the resource ARN includes the table name, so it is valid. Option B is incorrect because the policy allows Scan action. Option C is incorrect because the condition is on LeadingKeys, not on the table.
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 resource ARN does not include the table name.
Why it's wrong here
The ARN includes the table name 'Orders'.
✗
The Scan action is not allowed in the policy.
Why it's wrong here
Scan is listed in the Action array.
✗
The condition requires the partition key to be 'CustomerID', but the Scan operation does not specify a partition key.
Why it's wrong here
The condition 'LeadingKeys' applies to the partition key, but the issue is the use of 'ForAllValues'.
✓
The 'ForAllValues:StringEquals' condition set operator prevents the Scan operation because it requires all leading keys to match a single value, which is impossible for a Scan.
Why this is correct
'ForAllValues' evaluates to false if the request has no leading keys (as in Scan) or multiple keys.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
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.
Monitoring and Troubleshooting — This question tests Monitoring and Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The 'ForAllValues:StringEquals' condition set operator prevents the Scan operation because it requires all leading keys to match a single value, which is impossible for a Scan. — Option D is correct. The condition 'dynamodb:LeadingKeys' applies only to Query and Scan operations when the condition key is used to restrict partition key values. However, the condition 'ForAllValues:StringEquals' requires that all leading keys in the request match the specified value. For a Scan operation without a specific partition key, the condition cannot be satisfied, leading to denial. Option A is incorrect because the resource ARN includes the table name, so it is valid. Option B is incorrect because the policy allows Scan action. Option C is incorrect because the condition is on LeadingKeys, not on the table.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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