DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. 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 security engineer created the IAM policy above for an application that reads from a DynamoDB table named UserSessions. The application reports that it cannot query the table using a Global Secondary Index (GSI). The table's GSI is named GSI_UserSessions. Why is the application unable to query the index?
The Query action is not allowed on the index because the Allow statement only applies to the table, not the index.
Correct. The Allow statement only applies to the table, not the index, so the Query action is implicitly denied on the index.
B
The Deny statement explicitly denies all DynamoDB actions on the index resource, overriding the Allow statement.
Why wrong: Incorrect. Although a Deny statement would block access, the question's scenario does not specify that a Deny exists; the core issue is the missing Allow on the index resource.
C
The application is using GetItem instead of Query to access the index.
Why wrong: Incorrect. The application is using Query, not GetItem, as stated in the question.
D
The policy allows Query on the table, which automatically includes the index.
Why wrong: Incorrect. Allowing Query on the table does not automatically extend to the index; indexes require separate permissions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Query action is not allowed on the index because the Allow statement only applies to the table, not the index.
The IAM policy's Allow statement grants the Query action only on the table resource (arn:aws:dynamodb:...:table/UserSessions) but not on the index resource (arn:aws:dynamodb:...:table/UserSessions/index/GSI_UserSessions). In DynamoDB, a Global Secondary Index is a separate subresource, and IAM policies must explicitly include the index ARN to allow operations like Query on that index. Without an explicit Allow on the index, the default implicit deny prevents the query. Option B is incorrect because while a Deny statement would override any Allow, the primary reason the application fails is the lack of an Allow on the index; the Deny statement, if present, is an additional but not necessary condition.
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 Query action is not allowed on the index because the Allow statement only applies to the table, not the index.
Why this is correct
Correct. The Allow statement only applies to the table, not the index, so the Query action is implicitly denied on the index.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Deny statement explicitly denies all DynamoDB actions on the index resource, overriding the Allow statement.
Why it's wrong here
Incorrect. Although a Deny statement would block access, the question's scenario does not specify that a Deny exists; the core issue is the missing Allow on the index resource.
✗
The application is using GetItem instead of Query to access the index.
Why it's wrong here
Incorrect. The application is using Query, not GetItem, as stated in the question.
✗
The policy allows Query on the table, which automatically includes the index.
Why it's wrong here
Incorrect. Allowing Query on the table does not automatically extend to the index; indexes require separate permissions.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume that granting permissions on a DynamoDB table automatically covers its Global Secondary Indexes, but AWS IAM treats indexes as separate resources requiring explicit ARN-based permissions.
Trap categories for this question
Scenario analysis trap
Incorrect. Although a Deny statement would block access, the question's scenario does not specify that a Deny exists; the core issue is the missing Allow on the index resource.
Detailed technical explanation
How to think about this question
In DynamoDB IAM policies, table and index ARNs are distinct: a table ARN is arn:aws:dynamodb:region:account-id:table/TableName, while an index ARN is arn:aws:dynamodb:region:account-id:table/TableName/index/IndexName. When a Query operation targets a GSI, DynamoDB evaluates permissions against the index ARN, not the table ARN. This means a policy that only grants Query on the table will fail for index queries, even if the table itself is accessible. A common real-world scenario is when developers assume that table-level permissions cascade to indexes, leading to unexpected access denied errors.
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.
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
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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Workload-Specific Database Design — This question tests Workload-Specific Database Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Query action is not allowed on the index because the Allow statement only applies to the table, not the index. — The IAM policy's Allow statement grants the Query action only on the table resource (arn:aws:dynamodb:...:table/UserSessions) but not on the index resource (arn:aws:dynamodb:...:table/UserSessions/index/GSI_UserSessions). In DynamoDB, a Global Secondary Index is a separate subresource, and IAM policies must explicitly include the index ARN to allow operations like Query on that index. Without an explicit Allow on the index, the default implicit deny prevents the query. Option B is incorrect because while a Deny statement would override any Allow, the primary reason the application fails is the lack of an Allow on the index; the Deny statement, if present, is an additional but not necessary condition.
What should I do if I get this DBS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.