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

Question 1

A company is using an Amazon RDS for MySQL database for its e-commerce platform. During a recent flash sale, the database experienced high read traffic, causing slow query performance. The company needs a solution that offloads read traffic with minimal application changes. Which action should be taken?

Accepted Answer

Create an Amazon RDS read replica in the same region.. Creating an Amazon RDS read replica in the same region offloads read traffic from the primary DB instance by directing read queries to a read-only copy. This requires minimal application changes—only modifying the database connection string to point read queries to the replica endpoint. RDS read replicas use MySQL's native asynchronous replication, making them ideal for scaling read-heavy workloads like flash sales.

Answer

Enable DynamoDB Accelerator (DAX) on the RDS instance.

Answer

Migrate the database to Amazon Aurora and enable Aurora Global Database.

Answer

Implement Amazon ElastiCache for Redis to cache database queries.

Question 2

A data engineering team is designing a data lake on Amazon S3. They need to store raw data in its original format and transformed data in Parquet. The data is accessed by multiple analytics services, including Amazon Athena and Amazon Redshift Spectrum. Compliance requirements mandate that all data be encrypted at rest with AWS KMS and that the encryption keys be rotated every 90 days. Which S3 bucket configuration meets these requirements?

Accepted Answer

Use SSE-KMS with a customer-managed KMS key that has automatic key rotation enabled.. Option A is correct because SSE-KMS with a customer-managed KMS key allows you to enable automatic key rotation, which meets the 90-day rotation requirement. AWS KMS automatically rotates customer-managed keys annually, but you can also configure a custom rotation period (e.g., 90 days) using a Lambda function or AWS Config rule. This setup ensures raw and Parquet data are encrypted at rest, and the key rotation satisfies compliance mandates.

Answer

Use SSE-C with client-managed keys and rotate them manually.

Answer

Use a bucket policy to enforce encryption and rely on default S3 encryption.

Answer

Use SSE-S3 with default encryption enabled.

Question 3

A company uses Amazon DynamoDB as the primary data store for a gaming application. The application stores user profiles and game state. During peak hours, the application experiences throttling on writes to the UserProfiles table. The table's read capacity is underutilized. Which solution should resolve the write throttling?

Accepted Answer

Increase the provisioned write capacity units for the table.. Write throttling occurs when the number of write requests exceeds the provisioned write capacity units (WCUs) for the DynamoDB table. Since the read capacity is underutilized, the correct solution is to increase the provisioned WCUs to accommodate the peak write traffic. This directly addresses the capacity deficit without affecting read operations.

Answer

Enable DynamoDB Accelerator (DAX) on the table.

Answer

Add a global secondary index (GSI) to the table.

Answer

Configure auto scaling for read capacity units.

Question 4

A company is running a data warehouse on Amazon Redshift. The data engineering team notices that query performance has degraded over time. They suspect that data distribution is causing excessive data movement between nodes. The table is joined frequently on the customer_id column. Which column should be chosen as the distribution key to optimize join performance?

Accepted Answer

customer_id. The correct answer is B (customer_id) because Redshift distributes data across nodes based on the distribution key. When two tables are joined on customer_id, using it as the distribution key ensures that matching rows from both tables are co-located on the same node, eliminating the need for data redistribution (broadcast or shuffle) during the join. This minimizes network traffic and reduces query latency, directly addressing the performance degradation caused by excessive data movement.

Answer

AUTO distribution

Answer

order_date

Answer

EVEN distribution

Question 5

A company uses Amazon S3 to store sensitive financial data. The security team requires that all objects be encrypted at rest using AWS KMS with a customer-managed key. Additionally, they want to audit all KMS decrypt calls for compliance. Which configuration should be used to meet these requirements?

Accepted Answer

Use SSE-KMS with a customer-managed KMS key and enable CloudTrail data events for the key.. Option C is correct because SSE-KMS with a customer-managed key allows the company to control the encryption key lifecycle and meet the requirement for customer-managed keys. Enabling CloudTrail data events for the KMS key captures all decrypt API calls, providing the necessary audit trail for compliance.

Answer

Enable default encryption on the bucket with SSE-KMS using an AWS managed key.

Answer

Use SSE-S3 with a bucket policy that denies uploads without encryption.

Answer

Use SSE-C with client-managed keys and log S3 API calls.

Question 6

A data engineer needs to store time-series data from IoT devices. The data is write-heavy and requires low-latency queries by device ID and timestamp. The data volume is expected to grow to terabytes. Which AWS database service is most suitable?

Accepted Answer

Amazon Timestream. Amazon Timestream is purpose-built for time-series data, offering automatic tiered storage (in-memory for recent data and magnetic for historical) to handle write-heavy IoT workloads at scale. It supports low-latency queries by device ID and timestamp via its SQL-compatible query engine, making it the most suitable choice for terabytes of time-series data.

Answer

Amazon RDS for MySQL

Answer

Amazon ElastiCache for Redis

Answer

Amazon DynamoDB

Question 7

A company is migrating its on-premises Oracle database to Amazon Aurora PostgreSQL. The migration must have minimal downtime. The source database is 2 TB and runs on a single server. Which AWS service should be used for the migration?

Accepted Answer

AWS Database Migration Service (DMS). AWS Database Migration Service (DMS) is the correct choice because it supports homogeneous migrations from Oracle to Amazon Aurora PostgreSQL with minimal downtime using ongoing replication (change data capture). DMS can handle a 2 TB source database by performing a full load followed by continuous replication of changes from the Oracle redo logs, allowing the target Aurora database to stay nearly in sync until cutover.

Answer

AWS DataSync

Answer

Amazon S3 Transfer Acceleration

Answer

AWS Snowball Edge

Question 8

A company is using Amazon DynamoDB with auto scaling enabled. During a marketing campaign, write traffic spikes, and some write requests fail with ProvisionedThroughputExceededException. The auto scaling policy has a target utilization of 70% and a maximum capacity that is high enough. What is the most likely cause of the throttling?

Accepted Answer

Auto scaling cannot react quickly enough to sudden traffic spikes.. Auto scaling in DynamoDB adjusts capacity based on the average utilization over a period (typically 5-10 minutes). When a sudden traffic spike occurs, the write requests can exceed the current provisioned capacity before the auto scaling policy has time to react and increase the capacity. This delay causes ProvisionedThroughputExceededException errors, even though the maximum capacity is set high enough.

Answer

The table has a global secondary index that is throttling.

Answer

The table does not have enough maximum capacity.

Answer

The auto scaling policy is not configured correctly.

Question 9

A company is designing a data lake on Amazon S3. The data engineering team needs to implement a lifecycle policy to manage costs. Which TWO actions should be taken to reduce storage costs?

Accepted Answer

Transition objects to S3 Glacier Deep Archive after 90 days.. Option A is correct because transitioning objects to S3 Glacier Deep Archive after 90 days significantly reduces storage costs for data that is rarely accessed and can tolerate a retrieval time of 12 hours. This lifecycle policy is a standard cost-optimization strategy for data lakes where historical or cold data does not require immediate access.

Answer

Transition objects to S3 One Zone-IA after 30 days.

Answer

Enable S3 Intelligent-Tiering.

Answer

Transition objects to S3 Standard-IA after 30 days.

Question 10

A company is using Amazon Redshift for its data warehouse. The data engineering team needs to improve query performance for a large fact table that is frequently joined with multiple dimension tables. Which THREE strategies should be considered?

Accepted Answer

Define sort keys on columns used in WHERE clauses.. Option A is correct because defining sort keys on columns used in WHERE clauses allows Amazon Redshift to use zone maps to skip large blocks of data that do not satisfy the filter condition, dramatically reducing the amount of data scanned. This is especially effective for large fact tables where selective filters can prune entire disk blocks, improving query performance without additional hardware.

Answer

Use DISTSTYLE EVEN to distribute data evenly.

Answer

Increase the number of nodes in the cluster.

Question 11

A data engineer is setting up Amazon S3 bucket policies for a data lake. The security team requires that all objects uploaded to the bucket be encrypted at rest using server-side encryption. Which TWO methods can enforce encryption at upload time?

Accepted Answer

Enable S3 default encryption on the bucket.. Option D is correct because enabling S3 default encryption on the bucket automatically applies server-side encryption (SSE-S3 or SSE-KMS) to all objects uploaded without an encryption header, ensuring encryption at rest. Option E is correct because a bucket policy with a Deny effect on PutObject when the x-amz-server-side-encryption header is missing enforces encryption at upload time by rejecting unencrypted uploads, providing a complementary enforcement mechanism.

Answer

Enable S3 Transfer Acceleration.

Answer

Enable AWS CloudTrail to monitor uploads.

Answer

Enable AWS KMS automatic key rotation.

Question 12

A data engineer runs the AWS CLI command to retrieve the lifecycle configuration of the 'my-data-lake' bucket. The output is shown in the exhibit. What is the effect of this lifecycle policy?

Accepted Answer

Objects in the 'logs/' prefix are moved to S3 Standard-IA after 30 days, to Glacier after 90 days, and deleted after 365 days.. Option C is correct because the lifecycle policy explicitly applies to the 'logs/' prefix, transitioning objects to S3 Standard-IA after 30 days, then to Glacier after 90 days, and finally expiring (deleting) them after 365 days. The 'Expiration' action with 'Days: 365' permanently removes the objects, while the 'Transitions' define the storage class changes at the specified intervals.

Answer

Objects in the 'logs/' prefix are deleted after 365 days and their delete markers are removed.

Answer

All objects in the bucket are moved to STANDARD_IA after 30 days.

Answer

Objects in the 'logs/' prefix are moved to Glacier after 90 days and expired after 90 days.

Question 13

A company runs a real-time analytics platform on AWS. Data is ingested from thousands of IoT devices into Amazon Kinesis Data Streams. A Lambda function consumes the stream, processes the data, and writes the results to an Amazon DynamoDB table. The DynamoDB table has a provisioned write capacity of 1000 WCU, and the read capacity is set to 200 RCU. Recently, the company noticed that the Lambda function is failing with ProvisionedThroughputExceededException on DynamoDB writes. The Lambda function is configured with a batch size of 100 and a concurrency limit of 10. The Kinesis shard count is 4. The number of devices has increased, but the data volume per device has remained the same. The company needs to resolve the write throttling without increasing the DynamoDB write capacity. Which action should the data engineer take?

Accepted Answer

Reduce the batch size of the Lambda function to 10.. Reducing the batch size from 100 to 10 decreases the number of records processed per Lambda invocation, which reduces the burst of write requests to DynamoDB per invocation. This helps stay within the 1000 WCU limit without increasing capacity, as the same total throughput is spread across more invocations with smaller batches.

Answer

Increase the number of Kinesis shards to 8.

Answer

Increase the Lambda concurrency limit to 20.

Answer

Increase the batch size to 200.

Question 14

A company stores its application logs in Amazon S3. The logs are generated daily and need to be retained for 3 years for compliance. The logs are accessed frequently for the first 30 days, occasionally for the next 6 months, and rarely after that. The data engineering team wants to minimize storage costs while ensuring that logs are available for retrieval within 12 hours for the first 6 months and within 48 hours after that. The team also wants to automatically delete logs after 3 years. Which lifecycle policy should the team implement?

Accepted Answer

Transition to S3 Standard-IA after 30 days, to S3 Glacier Deep Archive after 6 months, delete after 3 years.. Option D is correct because it aligns with the access patterns and retrieval requirements: S3 Standard-IA after 30 days for occasional access with immediate retrieval, then S3 Glacier Deep Archive after 6 months for rare access with a 12-hour retrieval time (via expedited or standard retrieval), and deletion after 3 years. This minimizes storage costs while meeting the 48-hour retrieval window for older logs.

Answer

Transition to S3 One Zone-IA after 30 days, delete after 6 months.

Answer

Transition to S3 Standard-IA after 30 days, delete after 3 years.

Answer

Transition to S3 Standard-IA after 30 days, to S3 Glacier after 6 months, delete after 3 years.

Question 15

A company is migrating its on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 5 TB in size and supports a critical application that requires less than 30 minutes of downtime. The company has a 1 Gbps network connection to AWS. The data engineering team plans to use AWS Database Migration Service (DMS) with change data capture (CDC) to keep the target in sync. During the full load phase, DMS is taking longer than expected, and the team is concerned about meeting the downtime window. Which action should the team take to speed up the full load?

Accepted Answer

Create multiple DMS tasks to load different tables in parallel.. Creating multiple DMS tasks to load different tables in parallel (Option D) is the correct action because DMS performs full load sequentially within a single task. By splitting tables across multiple tasks, the team can parallelize the data transfer, utilizing the 1 Gbps network more efficiently and reducing the overall full load time to meet the 30-minute downtime window.

Answer

Increase the compute capacity of the target RDS instance.

Answer

Enable DMS validation to ensure data integrity.

Answer

Use AWS Snowball Edge to transfer the data offline.