DEA-C01 Data Store Management Practice Test 25 — 15 Questions

Question 1

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?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Objects are deleted after 365 days.. The lifecycle configuration is set to expire objects after 365 days, which means the S3 service will automatically delete the objects once they reach that age. Since the question states the engineer wants to ensure deletion after 365 days and the current behavior matches that, option A is correct. No transition actions are defined, so objects remain in the original storage class until expiration.

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 2

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. Amazon RDS for MySQL Read Replicas offload read traffic from the primary DB instance, directly improving read performance for a read-heavy workload. With a 2 TB database, Read Replicas can be created in the same or different regions, providing horizontal read scaling without impacting the primary instance's write capacity. Multi-AZ deployment already provides high availability but does not improve read performance, as the standby instance is not used for reads.

Answer

Use Amazon ElastiCache to cache database queries

Answer

Increase the instance size to 16xlarge

Answer

Enable Multi-AZ on additional instances

Question 3

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. S3 Standard-IA (Infrequent Access) is the most cost-effective choice because it offers low per-GB storage costs for data accessed infrequently, while still providing millisecond retrieval latency for immediate access when needed. This matches the requirement of storing large amounts of data that is rarely accessed but must be available instantly.

Answer

S3 Intelligent-Tiering

Answer

S3 One Zone-IA

Answer

S3 Glacier Deep Archive

Question 4

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

Switch to provisioned capacity with Auto Scaling. Switching from on-demand to provisioned capacity with Auto Scaling allows you to set a higher minimum and maximum read/write capacity, ensuring that the table can handle spikes up to 50,000 write requests per second without throttling. This change is made at the table level via the AWS console or CLI and does not require any application code modifications. In contrast, enabling DAX (Option D) would require updating the application to use the DAX client, violating the requirement to avoid application changes. Options A and B are ineffective or incompatible: writing data to S3 does not address DynamoDB write throttling, and increasing provisioned read capacity is not applicable for an on-demand table without switching capacity modes first.

Answer

Write data to Amazon S3 and use S3 Select

Answer

Increase the provisioned read capacity units

Answer

Enable DynamoDB Accelerator (DAX)

Question 5

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. Enabling default encryption on the S3 bucket with SSE-S3 automatically encrypts all objects at rest using AES-256, managed entirely by AWS. This requires no additional configuration or key management, providing the least operational overhead while meeting the encryption requirement for PII.

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)

Question 6

A company needs to migrate an on-premises 10 TB PostgreSQL database to Amazon RDS for PostgreSQL with minimal downtime. 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 is specifically designed for migrating databases to AWS with minimal downtime. It supports continuous replication from an on-premises PostgreSQL source to Amazon RDS for PostgreSQL using change data capture (CDC), allowing the source database to remain operational during the migration.

Answer

AWS Storage Gateway

Answer

AWS Snowball Edge

Answer

AWS DataSync

Question 7

A company is using Amazon Redshift for analytics. The cluster has 20 nodes and the data is evenly distributed. Query performance has degraded over time. The data engineer suspects that table maintenance is needed. Which set of operations should be performed to improve query performance?

Accepted Answer

Run VACUUM and ANALYZE commands on all tables. Over time, Amazon Redshift tables accumulate deleted rows and unsorted data due to UPDATE and DELETE operations, which degrades query performance. Running VACUUM reclaims space and re-sorts data according to the table's sort key, while ANALYZE updates table statistics used by the query optimizer. Together, these operations restore data layout and enable efficient query planning, directly addressing the performance degradation.

Answer

Run VACUUM FULL on all tables

Answer

Run REINDEX on all tables

Answer

Run ALTER TABLE APPEND to reorganize data

Question 8

A data engineer is setting up an Amazon S3 lifecycle policy to transition objects to S3 Glacier after 90 days and delete after 365 days. The objects are stored in the S3 Standard storage class. Which lifecycle rule configuration meets the requirements?

Accepted Answer

Transition to Glacier after 90 days and expire after 365 days. It specifies a transition action to S3 Glacier after 90 days and a separate expiration action after 365 days, which directly matches the requirements. S3 lifecycle policies allow independent transition and expiration actions, and the expiration action must be set to a value greater than the transition action to keep objects accessible in Glacier until deletion.

Answer

Transition to Glacier after 90 days and expire after 90 days

Answer

Transition to Glacier after 90 days and expire after 90 days

Answer

Transition to Glacier after 365 days and expire after 365 days

Question 9

A company needs to store JSON documents that are accessed by a key-value pattern. The data is 500 GB and requires single-digit millisecond latency. Which AWS database is most suitable?

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is the most suitable choice because it is a fully managed NoSQL key-value and document database that delivers single-digit millisecond latency at any scale, making it ideal for storing and retrieving JSON documents via a key-value access pattern. It supports document data types natively and can handle 500 GB of data efficiently with consistent low-latency performance.

Answer

Amazon Redshift

Answer

Amazon Neptune

Answer

Amazon RDS for MySQL

Question 10

A company is using Amazon RDS for SQL Server with Multi-AZ. The database has a 500 GB data file and 100 GB log file. The application experiences high latency during peak hours. Monitoring shows high WriteIOPS on the primary. Which change will reduce latency without losing the ability to failover?

Accepted Answer

Increase the provisioned IOPS on the RDS instance. The high WriteIOPS on the primary indicates that the storage layer is saturated, causing latency. Increasing provisioned IOPS on the RDS instance directly addresses the bottleneck by providing more I/O capacity, and since Multi-AZ is already enabled, the standby remains synchronized and failover capability is preserved.

Answer

Reduce the log file size by changing recovery model

Answer

Create a Read Replica in a different Availability Zone

Answer

Switch to Multi-AZ with two readable standbys

Question 11

Which TWO actions can reduce the cost of an Amazon S3 bucket that stores infrequently accessed data? (Choose 2.)

Accepted Answer

Use lifecycle policies to expire objects after a certain period. Lifecycle policies allow you to define rules that automatically expire (delete) objects after a specified period, which directly reduces storage costs by removing data that is no longer needed. For infrequently accessed data, deleting obsolete objects prevents paying for unnecessary storage over time.

Answer

Enable cross-region replication

Answer

Enable versioning to keep multiple versions

Answer

Enable MFA Delete for extra security

Question 12

Which THREE steps are recommended for migrating an on-premises Oracle database to Amazon RDS for Oracle with minimal downtime? (Choose 3.)

Accepted Answer

Set up a VPN or Direct Connect between on-premises and AWS. Establishing a VPN or Direct Connect provides a secure, private, and low-latency network connection between the on-premises environment and AWS. This is essential for minimizing downtime during a migration, as it ensures reliable and fast data transfer for both the initial full load and ongoing replication, reducing the risk of network interruptions that could extend the migration window.

Answer

Disable archiving on the source database

Answer

Perform a full load migration without change data capture

Question 13

Which THREE are valid Amazon Redshift distribution styles? (Choose 3.)

Accepted Answer

ALL. All three distribution styles—ALL, AUTO, and KEY—are valid in Amazon Redshift. AUTO lets Redshift choose the distribution style based on table size and query patterns, ALL copies the entire table to every node for small dimension tables, and KEY distributes rows based on a specified column. The options HASH and RANDOM are not valid distribution styles.

Answer

HASH

Answer

RANDOM

Question 14

A company is running a production Amazon RDS for MySQL Multi-AZ DB instance. The database experiences a sudden spike in read requests, causing performance degradation. The company needs to improve read scalability with minimal application changes. Which solution should the data engineer recommend?

Accepted Answer

Create an Amazon RDS Read Replica and update the application to use it for read queries.. Amazon RDS Read Replicas allow you to offload read traffic from the primary DB instance by creating asynchronous replicas that can serve read queries. This directly addresses the spike in read requests with minimal application changes—only the connection string for read queries needs to be updated. Multi-AZ is for high availability, not read scaling, and increasing instance size is a vertical scaling approach that doesn't leverage the horizontal read scalability of replicas.

Answer

Implement DynamoDB Accelerator (DAX) in front of the database.

Answer

Enable Multi-AZ on the existing DB instance.

Answer

Increase the DB instance size to a larger instance class.

Question 15

A data engineer needs to store semi-structured JSON data that is accessed infrequently but must be retrievable within 5 minutes. The data is immutable once stored. Which storage solution is MOST cost-effective?

Accepted Answer

Amazon S3 Glacier Instant Retrieval. Amazon S3 Glacier Instant Retrieval is the most cost-effective choice for long-term archival of infrequently accessed, immutable data with a 5-minute retrieval requirement. It offers a storage cost of $0.004/GB/month, significantly lower than One Zone-IA at $0.01/GB/month, and retrieval times of milliseconds to minutes, easily meeting the 5-minute requirement. One Zone-IA is cheaper than S3 Standard but more expensive than Glacier Instant Retrieval, and its single-AZ design introduces availability risk. Glacier Deep Archive has a higher retrieval cost and typically takes hours, exceeding the 5-minute requirement.

Answer

Amazon S3 Glacier Deep Archive

Answer

Amazon S3 Standard

Answer

Amazon S3 One Zone-IA