DynamoDB IAM LeadingKeys Condition — Restrict Access to Specific Partition Key
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
✓
Read and write items only where the partition key equals 'customer_123'
The IAM policy uses a condition key `dynamodb:LeadingKeys` with a condition operator `ForAllValues:StringEquals` to restrict access to items where the partition key equals 'customer_123'. This allows the user to perform read and write operations only on items matching that specific partition key value, enforcing fine-grained access control at the item level.
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.
✓
Read and write items only where the partition key equals 'customer_123'
Why this is correct
The condition restricts operations to items with LeadingKeys 'customer_123'.
Related concept
Read the scenario before looking for a memorised answer.
✗
Read and write any item in the Orders table
Why it's wrong here
The condition restricts access to a specific partition key value.
✗
Scan the entire Orders table
Why it's wrong here
Scan is not allowed because the policy only allows GetItem and PutItem.
✗
Perform all DynamoDB actions on the Orders table
Why it's wrong here
Only GetItem and PutItem are allowed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume a policy restricting access to a specific partition key still allows a full table Scan, but DynamoDB's fine-grained access control with `dynamodb:LeadingKeys` explicitly denies any operation that does not specify the allowed partition key, including Scans.
Detailed technical explanation
How to think about this question
Under the hood, the `dynamodb:LeadingKeys` condition key evaluates the partition key value of the item being accessed. For a Query operation, DynamoDB checks the condition against the specified partition key; for GetItem, it checks the key of the requested item. This mechanism is part of AWS IAM's fine-grained access control, which uses condition keys to enforce row-level security without requiring a separate table per user. In real-world scenarios, this is commonly used in multi-tenant applications where each customer's data is isolated by partition key.
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: Read and write items only where the partition key equals 'customer_123' — The IAM policy uses a condition key `dynamodb:LeadingKeys` with a condition operator `ForAllValues:StringEquals` to restrict access to items where the partition key equals 'customer_123'. This allows the user to perform read and write operations only on items matching that specific partition key value, enforcing fine-grained access control at the item level.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses the IAM policy shown in the exhibit to control access to a DynamoDB table. The table has a partition key user_id and a sort key timestamp. The application uses the AWS SDK to query items. When a user tries to query items with a filter condition, they receive an AccessDeniedException. What is the most likely cause?
medium
A.The aws:userid variable is not being resolved correctly.
✓ B.The query does not specify a partition key that matches the user's LeadingKeys condition.
C.The policy is missing a Condition element with dynamodb:Select.
D.The policy does not allow the Query action.
Why B: The IAM policy uses a `Condition` block with `ForAllValues:StringEquals` on `dynamodb:LeadingKeys` to restrict access to items where the partition key (`user_id`) matches the caller's IAM user ID (`${aws:userid}`). When a query does not specify a partition key that satisfies this condition, the request fails with an `AccessDeniedException`. The error occurs because the query must include a partition key equal to the user's ID to pass the leading keys restriction.
Variation 2. A company is implementing fine-grained access control for a DynamoDB table named UserSessions. The table has a partition key of 'user_id'. The above IAM policy is attached to an IAM role assumed by the application. What does this policy achieve?
easy
A.Allows the application to perform all operations on the UserSessions table without restrictions
✓ B.Restricts the application to access only items where the partition key matches the user's AWS user ID
C.Allows the application to read but not write items in the UserSessions table
D.Allows the application to access only the UserSessions table but not other tables
Why B: The IAM policy uses a condition key `dynamodb:LeadingKeys` with a value of `${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.
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.