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.
A company is implementing fine-grained access control for a DynamoDB table named UserSessions. The table has a partition key of 'user_id'. The above IAM policy is attached to an IAM role assumed by the application. What does this policy achieve?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Restricts the application to access only items where the partition key matches the user's AWS user ID
The IAM policy uses a condition key `dynamodb:LeadingKeys` with a value of `${aws:userid}`. This restricts access to items in the DynamoDB table where the partition key (`user_id`) matches the unique identifier of the IAM user or role that is making the request. This implements fine-grained access control, ensuring the application can only read or write items belonging to the authenticated user.
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.
✗
Allows the application to perform all operations on the UserSessions table without restrictions
Why it's wrong here
The condition restricts access based on the partition key; it does not grant unrestricted access.
✓
Restricts the application to access only items where the partition key matches the user's AWS user ID
Why this is correct
The condition uses 'aws:userid' to limit access to items with the corresponding partition key.
Related concept
Read the scenario before looking for a memorised answer.
✗
Allows the application to read but not write items in the UserSessions table
Why it's wrong here
The policy allows PutItem, UpdateItem, and DeleteItem, so write operations are permitted.
✗
Allows the application to access only the UserSessions table but not other tables
Why it's wrong here
The policy grants access to the UserSessions table only, but with the condition, it further restricts to specific items.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse `aws:userid` with the IAM user name or the partition key value, or they assume the policy grants full access (Option A) without noticing the condition that enforces row-level security.
Detailed technical explanation
How to think about this question
The `dynamodb:LeadingKeys` condition key evaluates the partition key value of the item being accessed against the provided expression. The `${aws:userid}` variable resolves to the unique ID of the IAM principal (e.g., `AROA...:role-session-name` for assumed roles). This mechanism is essential for multi-tenant applications where each user should only see their own data, and it works with both Query and GetItem operations but not with Scan unless a filter is applied, which can lead to unintended data exposure if not carefully implemented.
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: Restricts the application to access only items where the partition key matches the user's AWS user ID — The IAM policy uses a condition key `dynamodb:LeadingKeys` with a value of `${aws:userid}`. This restricts access to items in the DynamoDB table where the partition key (`user_id`) matches the unique identifier of the IAM user or role that is making the request. This implements fine-grained access control, ensuring the application can only read or write items belonging to the authenticated user.
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.
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Question Discussion
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