DEA-C01 Data Store Management Practice Test 24 — 15 Questions

Question 1

A company uses Amazon Redshift for data warehousing. The data engineer notices that query performance has degraded over time. The tables are frequently updated with new data, and the data engineer suspects that the distribution style is causing data skew. Which distribution style should the data engineer use to minimize data skew?

Accepted Answer

EVEN distribution. Option A is correct because EVEN distribution distributes rows across slices evenly, minimizing skew when no good distribution key exists. Option B is wrong because KEY distribution can cause skew if the key is not unique. Option C is wrong because ALL distribution duplicates the table, which is not efficient for large tables. Option D is wrong because AUTO lets Redshift choose, but may not minimize skew if the key is poorly chosen.

Answer

KEY distribution on a column with high cardinality

Answer

AUTO distribution

Answer

ALL distribution

Question 2

A company is designing a data lake on Amazon S3. The data includes personal identifiable information (PII). The data engineer must ensure that only authorized users can access the data, and that access is logged for auditing. Which combination of services should the data engineer use?

Accepted Answer

S3 bucket policies with IAM policies and AWS CloudTrail with data events. Option C is correct because S3 bucket policies and IAM policies control access, and CloudTrail logs data events for auditing. Option A is wrong because KMS is for encryption, not access control or logging. Option B is wrong because VPC endpoints are for network isolation, not logging. Option D is wrong because Macie is for data discovery and classification, not access control.

Answer

Amazon S3 access points and VPC endpoints

Answer

Amazon Macie to discover PII and S3 Object Lock to prevent deletion

Answer

AWS KMS to encrypt data and AWS CloudTrail to log access

Question 3

A company is storing large amounts of log data in Amazon S3. The data is accessed frequently for the first 30 days, then rarely after that. The company wants to automatically transition the data to a lower-cost storage class after 30 days. Which S3 feature should the data engineer use?

Accepted Answer

S3 Lifecycle policies. Option B is correct because S3 Lifecycle policies automatically transition objects between storage classes. Option A is wrong because S3 Intelligent-Tiering monitors access patterns but may have monitoring costs. Option C is wrong because S3 replication is for copying data, not transitioning storage classes. Option D is wrong because S3 Batch Operations is for bulk actions, not automatic transitions.

Answer

S3 Intelligent-Tiering

Answer

S3 Cross-Region Replication

Answer

S3 Batch Operations

Question 4

A company is using Amazon DynamoDB to store session data for a web application. The data engineer needs to ensure that the data is encrypted at rest. Which action should the data engineer take?

Accepted Answer

Ensure encryption at rest is enabled on the DynamoDB table (default).. Option B is correct because DynamoDB supports encryption at rest using AWS KMS, and it is enabled by default. Option A is wrong because DynamoDB Accelerator (DAX) does not provide encryption at rest for the underlying table. Option C is wrong because enabling encryption on the client side is unnecessary and adds complexity. Option D is wrong because the question is about encryption at rest, not TTL.

Answer

Enable encryption at rest on the DynamoDB Accelerator (DAX) cluster.

Answer

Use client-side encryption before writing to DynamoDB.

Answer

Enable DynamoDB Time to Live (TTL) to encrypt data.

Question 5

A company is using Amazon S3 to store sensitive data. The security team requires that all data be encrypted at rest using a customer-managed AWS KMS key. The data engineer must ensure that only a specific IAM role can decrypt the data. Which policy should the data engineer attach to the KMS key?

Accepted Answer

A KMS key policy that allows the IAM role to perform kms:Decrypt. Option C is correct because the KMS key policy must grant the IAM role permission to decrypt. Option A is wrong because the IAM policy alone is not sufficient; KMS key policy must allow the role to decrypt. Option B is wrong because the S3 bucket policy controls access to S3, not KMS. Option D is wrong because the IAM user policy is less secure and doesn't address role-based access.

Answer

An IAM user policy that allows kms:Decrypt for the specific key

Answer

An IAM policy attached to the role that allows kms:Decrypt

Answer

An S3 bucket policy that denies access unless encryption is used

Question 6

Which TWO statements are true about Amazon Redshift distribution styles? (Choose TWO.)

Accepted Answer

ALL distribution copies the entire table to every node.. Option A is correct: EVEN distribution distributes rows evenly, reducing data movement. Option D is correct: ALL distribution copies entire table to every node, which can improve join performance but uses more storage. Option B is wrong because KEY distribution can cause skew. Option C is wrong because AUTO distribution lets Redshift choose. Option E is wrong because Redshift does not use ROUND ROBIN; it uses EVEN, KEY, ALL, AUTO.

Answer

KEY distribution is always the best choice to minimize data skew.

Answer

AUTO distribution always selects EVEN distribution.

Answer

Redshift automatically assigns a ROUND ROBIN distribution style by default.

Question 7

Which THREE actions can help improve read performance in Amazon DynamoDB? (Choose THREE.)

Accepted Answer

Use parallel scans to distribute read load across partitions.. Option A is correct: DAX provides in-memory caching for reads. Option C is correct: Using strongly consistent reads can improve performance for read-after-write scenarios, but eventually consistent reads are faster; however, the question asks for actions that help read performance; both consistent read types are supported; but note: strongly consistent reads may have higher latency. Actually, to improve performance, eventually consistent reads are faster. Wait, the question says 'help improve read performance' – using eventually consistent reads is better. But option C says 'Use strongly consistent reads' which is incorrect for performance. Let me re-evaluate. I think correct answers are A, D, E. Option B is wrong because global tables replicate writes, not improve read performance. Option C is wrong because strongly consistent reads are slower. Option D is correct: adjusting read capacity units improves performance. Option E is correct: using parallel scans improves performance. So I will mark A, D, E as correct. But the stem says 'Choose THREE', so I need exactly three. Let me set correct flags accordingly.

Answer

Use DynamoDB global tables to replicate data.

Answer

Use strongly consistent reads for all queries.

Question 8

Which TWO are benefits of using Amazon S3 Object Lock? (Choose TWO.)

Accepted Answer

Helps meet regulatory requirements for write-once-read-many (WORM) storage.. Option A is correct: Object Lock prevents object deletion for a specified retention period. Option D is correct: Object Lock helps meet regulatory requirements for WORM storage. Option B is wrong: Versioning is separate from Object Lock. Option C is wrong: Object Lock does not automatically transition data. Option E is wrong: Encryption is separate from Object Lock.

Answer

Encrypts objects at rest using AWS KMS.

Answer

Automatically transitions objects to lower-cost storage classes.

Answer

Enables automatic versioning of objects.

Question 9

A data engineer is analyzing a DynamoDB table for a session management application. The table currently has 10,000 items and is 1 MB in size. The application expects 1,000 writes per second during peak hours. What should the data engineer do to accommodate the write workload?

Accepted Answer

Increase the write capacity units (WCU) for the table.. Option C is correct because the table has 5 write capacity units (WCU), which allows only 5 writes per second. To handle 1,000 writes per second, the WCU must be increased. Option A is wrong because DAX is a read cache. Option B is wrong because global tables replicate writes, but don't increase capacity. Option D is wrong because reducing item size doesn't increase write capacity enough.

Answer

Reduce the item size to improve write performance.

Answer

Use global tables to distribute writes across regions.

Answer

Enable DynamoDB Accelerator (DAX) to offload writes.

Question 10

A data engineer is reviewing an IAM policy that controls access to an S3 bucket. The policy is attached to a user group. The engineer notices that users are unable to download objects from the bucket. What is the likely cause?

Accepted Answer

The objects are encrypted using SSE-KMS, not SSE-S3.. Option B is correct because the policy condition requires that objects be encrypted with SSE-S3 (AES256). If the objects are encrypted with SSE-KMS or not encrypted, the request fails. Option A is wrong because the policy allows s3:GetObject. Option C is wrong because the policy does not restrict bucket names. Option D is wrong because the policy is attached to a user group, not a role; but that is not the issue.

Answer

The policy is attached to a user group instead of an IAM role.

Answer

The policy does not specify the correct bucket ARN.

Answer

The policy does not allow the s3:GetObject action.

Question 11

A data engineer is reviewing the lifecycle configuration of an S3 bucket. The bucket stores log files. The engineer wants to ensure that objects are deleted after 365 days. What is the current behavior?

Accepted Answer

Objects are deleted after 365 days.. Option A is correct because the expiration rule deletes objects after 365 days. Option B is wrong because there is no transition to Glacier. Option C is wrong because objects transition to STANDARD_IA after 30 days, not immediately. Option D is wrong because noncurrent versions are not included.

Answer

Objects are transitioned to S3 Standard-IA immediately.

Answer

Objects are transitioned to S3 Glacier after 365 days.

Answer

Noncurrent versions of objects are deleted after 365 days.

Question 12

A company is using Amazon RDS for MySQL with Multi-AZ deployment. The database size is 2 TB and the workload is read-heavy. To improve read performance, which option should be used?

Accepted Answer

Create Read Replicas in the same or different regions. Option C is correct because Read Replicas offload read traffic from the primary instance. Option A is wrong because Multi-AZ is for high availability, not read scaling. Option B is wrong because increasing instance size helps but is less efficient than adding replicas. Option D is wrong because ElastiCache is for caching, not directly for MySQL read scaling.

Answer

Use Amazon ElastiCache to cache database queries

Answer

Increase the instance size to 16xlarge

Answer

Enable Multi-AZ on additional instances

Question 13

A data engineer needs to store large amounts of data that is accessed infrequently but must be retrieved immediately when needed. Which Amazon S3 storage class is most cost-effective?

Accepted Answer

S3 Standard-IA. Option A is correct because S3 Standard-IA is for infrequent access with immediate retrieval. Option B is wrong because S3 Glacier has retrieval delays. Option C is wrong because S3 One Zone-IA is for data that can be recreated. Option D is wrong because S3 Intelligent-Tiering monitors access patterns but may not be the most cost-effective if access pattern is known.

Answer

S3 Intelligent-Tiering

Answer

S3 One Zone-IA

Answer

S3 Glacier Deep Archive

Question 14

A company uses Amazon DynamoDB with on-demand capacity for a gaming leaderboard. The table has 100 GB of data and receives 10,000 write requests per second with spikes to 50,000. The application experiences throttling during spikes. Which action should be taken to reduce throttling without changing the application?

Accepted Answer

Enable DynamoDB Accelerator (DAX). Option D is correct because DynamoDB Accelerator (DAX) provides in-memory caching to absorb read spikes and reduce write throttling by offloading reads. Option A is wrong because increasing read capacity does not help write throttling. Option B is wrong because Auto Scaling is not available with on-demand mode. Option C is wrong because S3 is not suitable for real-time writes.

Answer

Write data to Amazon S3 and use S3 Select

Answer

Increase the provisioned read capacity units

Answer

Switch to provisioned capacity with Auto Scaling

Question 15

A data engineer is designing a data lake on Amazon S3. The data includes personally identifiable information (PII) that must be encrypted at rest. Which combination of actions meets the encryption requirement with the least operational overhead?

Accepted Answer

Enable default encryption on the S3 bucket using SSE-S3. Option B is correct because S3 managed keys (SSE-S3) provide encryption at rest with minimal management. Option A is wrong because client-side encryption requires application changes. Option C is wrong because KMS adds key management overhead. Option D is wrong because bucket policies do not encrypt data.

Answer

Apply a bucket policy that denies access to unencrypted requests

Answer

Use client-side encryption with AWS KMS

Answer

Use server-side encryption with AWS KMS (SSE-KMS)