DEA-C01 Data Store Management Practice Test 33 — 15 Questions

Question 1

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.

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Amazon Redshift

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Amazon Neptune

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Amazon RDS for MySQL

Question 2

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.

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Enable cross-region replication

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Enable versioning to keep multiple versions

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Enable MFA Delete for extra security

Question 3

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.

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Disable archiving on the source database

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Perform a full load migration without change data capture

Question 4

A data engineer needs to migrate an on-premises Apache Hadoop cluster to AWS. The cluster stores data in HDFS and runs MapReduce jobs. The company wants to minimize operational overhead and leverage serverless technologies where possible. Which AWS service should the data engineer use to replace HDFS storage?

Accepted Answer

Amazon S3. Amazon S3 is the correct replacement for HDFS because it provides highly durable, scalable, and serverless object storage that can be used as the primary storage layer for Amazon EMR. Unlike HDFS, S3 decouples storage from compute, eliminating the need to manage cluster storage and allowing jobs to run on ephemeral clusters, which minimizes operational overhead. S3 integrates with EMR via the EMR File System (EMRFS), enabling MapReduce jobs to read/write data directly from S3 as if it were HDFS.

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Amazon EBS

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Amazon EMR

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Amazon Redshift

Question 5

A data engineer is designing a data lake on AWS using Amazon S3. The data consists of CSV files generated by IoT devices. The data is accessed by multiple analytics jobs, and the engineer needs to ensure that new files are immediately visible to all consumers after writing. What S3 consistency model applies?

Accepted Answer

Strong consistency for all operations.. Amazon S3 now provides strong consistency for all operations. After a successful write of a new object (or overwrite of an existing object), any subsequent read request immediately receives the latest version of the object, and list operations are also strongly consistent. Therefore, for new CSV files written to S3, the applicable model is strong consistency for all operations.

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Consistent reads require S3 Object Lock.

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Eventual consistency for all operations.

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Read-after-write consistency for new object PUTS.

Question 6

A company has an Amazon RDS for PostgreSQL DB instance with a large table that is frequently updated. The data engineer needs to reduce storage costs by archiving old records that are no longer accessed. The archived records must be retained for 7 years due to compliance requirements. Which solution is MOST cost-effective?

Accepted Answer

Export old records using pg_dump and store in S3 Glacier Deep Archive.. Exporting old records via pg_dump and storing them in S3 Glacier Deep Archive provides the lowest-cost storage for data that must be retained for 7 years but is never accessed. S3 Glacier Deep Archive offers retrieval times of 12–48 hours at a storage cost of approximately $0.00099/GB/month, far cheaper than any RDS storage tier. This approach removes the archived data from the RDS instance, reducing provisioned storage costs while meeting compliance requirements.

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Use RDS native backup and restore to keep a separate backup.

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Enable storage autoscaling on the RDS instance.

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Move old records to a separate table in the same RDS instance.

Question 7

A data engineer is designing a multi-region disaster recovery plan for an Amazon DynamoDB table. The table stores critical user profile data and must have a Recovery Point Objective (RPO) of less than 1 minute and a Recovery Time Objective (RTO) of less than 5 minutes. Which solution meets these requirements?

Accepted Answer

Use DynamoDB global tables to replicate data to another region.. DynamoDB global tables provide active-active multi-region replication with sub-second latency, ensuring that data written in one region is automatically replicated to other regions within seconds. This meets the RPO of less than 1 minute and RTO of less than 5 minutes because the table is already available in the secondary region for immediate reads and writes, with no manual restore or failover steps required.

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Configure DynamoDB Streams and a Lambda function to replicate data to another region.

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Use DynamoDB on-demand backup and restore to another region.

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Enable point-in-time recovery (PITR) and restore to another region.

Question 8

A company uses Amazon S3 to store customer documents. The data engineer needs to ensure that all objects uploaded to a specific S3 bucket are automatically encrypted with a customer-managed AWS KMS key. What should the data engineer do?

Accepted Answer

Set default encryption on the bucket to use SSE-KMS with the customer-managed key.. Setting default encryption on the S3 bucket to SSE-KMS with the customer-managed key ensures that all objects uploaded without explicit encryption headers are automatically encrypted using that KMS key. This satisfies the requirement without relying on client-side behavior, as S3 applies the encryption server-side at the time of write.

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Use pre-signed URLs for all uploads that include encryption parameters.

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Create a bucket policy that denies uploads without encryption.

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Enable S3 Versioning on the bucket.

Question 9

A company stores sensitive financial data in an Amazon Redshift cluster. The data engineer must ensure that all queries are logged for audit purposes and that the logs are stored in Amazon S3 with server-side encryption. Which THREE steps should the data engineer take to meet these requirements?

Accepted Answer

Configure audit logs to be stored in an Amazon S3 bucket.. Amazon Redshift audit logs can be configured to be stored directly in an Amazon S3 bucket, which is a native feature for exporting connection logs, user logs, and query logs. This satisfies the requirement to log all queries for audit purposes without relying on external services.

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Enable encryption on the Redshift cluster.

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Enable AWS CloudTrail to log Redshift queries.

Question 10

A data engineer is optimizing an Amazon RDS for MySQL database that experiences high write throughput. The engineer wants to improve write performance and reduce latency. Which TWO database-level configuration changes can help achieve this?

Accepted Answer

Use Provisioned IOPS (io1 or io2) storage.. Provisioned IOPS (io1 or io2) storage delivers consistent and predictable I/O performance by guaranteeing a specified number of I/O operations per second, which directly reduces latency and improves write throughput for high-write workloads. This is the most effective storage-level change for write-intensive RDS for MySQL databases.

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Reduce the backup retention period to 1 day.

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Create a Read Replica to offload writes.

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Enable Multi-AZ for high availability.

Question 11

A company is using Amazon RDS for MySQL with Multi-AZ deployment. The primary DB instance experiences a hardware failure, causing automatic failover to the standby. After the failover, the application reports that the database endpoint is unreachable for about 60 seconds. What is the MOST likely cause?

Accepted Answer

The DNS record for the DB instance endpoint needed to update to point to the new primary.. After an automatic failover in Amazon RDS Multi-AZ, the DNS record for the DB instance endpoint is updated to point to the new primary. This DNS change can take up to 60 seconds to propagate, during which the application may receive 'unreachable' errors if it caches the old DNS resolution. The 60-second outage aligns with the typical TTL (Time To Live) of 30 seconds for RDS DNS records plus propagation delays.

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The standby instance took longer than expected to promote to primary.

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The standby instance was not in a synchronized state and required a manual promotion.

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The application was using the wrong endpoint and needed to be reconfigured.

Question 12

A company stores critical financial data in Amazon DynamoDB. To meet compliance requirements, the data must be encrypted at rest with a customer-managed key. Which solution should the data engineer implement?

Accepted Answer

Configure the DynamoDB table to use a customer managed key from AWS KMS.. AWS DynamoDB integrates with AWS KMS to support encryption at rest using customer-managed keys (CMKs). By selecting a customer-managed key from KMS during table creation or via an update, the company can meet compliance requirements for controlling the encryption key lifecycle, including rotation and access policies. This approach ensures that the data is encrypted using AES-256 encryption, with the key material managed by the customer rather than AWS.

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Use AWS CloudHSM to generate a key and import it into DynamoDB.

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Enable default encryption on the DynamoDB table using S3-managed keys.

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Use AWS Certificate Manager to issue a certificate and configure TLS.

Question 13

A company uses Amazon Redshift for analytics. The data engineer notices that queries are slow and the system is experiencing high disk usage. The engineer suspects that the distribution style is suboptimal. Which action should the engineer take to improve query performance?

Accepted Answer

Use the DISTSTYLE AUTO setting and analyze query patterns to let Redshift choose.. DISTSTYLE AUTO allows Amazon Redshift to automatically assign distribution styles (KEY, EVEN, or ALL) based on query patterns and table size, optimizing data distribution for improved query performance. This is particularly effective when the engineer suspects suboptimal distribution but lacks detailed knowledge of the ideal key, as Redshift analyzes workload patterns to reduce data movement and disk usage.

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Convert all tables to use SORTKEY on the most frequently filtered column.

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Increase the number of nodes in the cluster to distribute data across more slices.

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Set all tables to DISTSTYLE EVEN to distribute data evenly.

Question 14

A data engineer needs to store semi-structured JSON data from IoT devices. The data is written frequently and read occasionally. Which AWS service is MOST cost-effective for this use case?

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is the most cost-effective choice because it is a fully managed NoSQL key-value and document database that natively supports semi-structured JSON data, offers single-digit millisecond latency for frequent writes, and provides a pay-per-request pricing model ideal for workloads with occasional reads. Its on-demand capacity mode automatically scales to handle high write throughput without provisioning, making it cheaper than provisioned alternatives for spiky or unpredictable IoT ingestion patterns.

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Amazon ElastiCache for Redis

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Amazon RDS for MySQL

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Amazon Redshift

Question 15

A company is using Amazon S3 to store sensitive customer data. The security team requires that all data be encrypted in transit and at rest. Additionally, they want to prevent any accidental public access. Which combination of actions should the data engineer take?

Accepted Answer

Enable default encryption with SSE-S3, enforce HTTPS only via bucket policy, and enable S3 Block Public Access.. Enabling default encryption with SSE-S3 ensures data is encrypted at rest automatically, enforcing HTTPS only via bucket policy ensures encryption in transit by rejecting HTTP requests, and enabling S3 Block Public Access prevents any accidental public exposure regardless of bucket policies or ACLs. This combination satisfies all security requirements: encryption in transit, encryption at rest, and prevention of public access.

Answer

Enable default encryption with SSE-KMS, allow both HTTP and HTTPS, and set bucket ACLs to private.

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Use client-side encryption, enforce HTTPS via bucket policy, and enable S3 Block Public Access.

Answer

Enable default encryption with SSE-S3, allow HTTP and HTTPS, and use bucket ACLs to block public access.