DEA-C01 Data Store Management Practice Test 26 — 15 Questions

Question 1

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 multi-region active-active replication with sub-second replication latency, meeting RPO < 1 minute and RTO < 5 minutes (by failing over to another region). Option A is wrong because on-demand backup and restore can take hours to restore. Option B is wrong because point-in-time recovery (PITR) restores to a new table, which can take minutes to hours. Option D is wrong because cross-region replication using Lambda is custom and may have higher latency.

Answer

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

Answer

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

Answer

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

Question 2

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 a default encryption policy on the bucket with SSE-KMS ensures all objects are encrypted with the specified KMS key. Option A is wrong because bucket policies can enforce encryption but don't automatically encrypt. Option B is wrong because enabling S3 Versioning doesn't enforce encryption. Option D is wrong because pre-signed URLs don't enforce encryption.

Answer

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

Answer

Create a bucket policy that denies uploads without encryption.

Answer

Enable S3 Versioning on the bucket.

Question 3

A data engineer is designing a data pipeline that ingests streaming data from IoT devices into Amazon S3 using Amazon Kinesis Data Firehose. The data must be transformed from JSON to Parquet format before storage. Which TWO actions should the data engineer take to achieve this?

Accepted Answer

Create a Glue Data Catalog table defining the schema and configure Firehose to use the table for Parquet conversion.. Kinesis Data Firehose can convert JSON to Parquet using a schema from a Glue Data Catalog table. Option C is correct because Firehose can use an AWS Lambda function for transformation. Option E is correct because Firehose can directly convert to Parquet if a schema is provided via Glue Data Catalog. Option A is wrong because Firehose does not support direct conversion to Avro without a schema. Option B is wrong because Kinesis Data Analytics is for real-time analytics, not format conversion. Option D is wrong because Firehose cannot directly convert to Parquet without a schema; it needs Glue Data Catalog.

Answer

Enable Firehose's built-in Parquet conversion without any additional configuration.

Answer

Use Amazon Kinesis Data Analytics to convert the data format.

Answer

Configure Firehose to convert the data to Apache Avro format.

Question 4

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.. To audit queries, enable audit logging, set the bucket to S3, and ensure encryption is enabled. Option A is correct because audit logging captures query logs. Option B is correct because audit logs are stored in S3. Option D is correct because enabling default encryption on the S3 bucket encrypts the logs. Option C is wrong because user activity logging in CloudTrail does not capture query logs. Option E is wrong because enabling encryption on the Redshift cluster encrypts data at rest, not the audit logs.

Answer

Enable encryption on the Redshift cluster.

Answer

Enable AWS CloudTrail to log Redshift queries.

Question 5

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.. Increasing the DB instance class provides more CPU and memory, which can improve write performance. Enabling Multi-AZ helps with availability but not write performance directly. Option C is correct because using Provisioned IOPS (io1/io2) storage provides consistent low-latency writes. Option D is wrong because Read Replicas are for read scaling. Option E is wrong because reducing retention period of automated backups frees up storage but doesn't improve write performance.

Answer

Reduce the backup retention period to 1 day.

Answer

Create a Read Replica to offload writes.

Answer

Enable Multi-AZ for high availability.

Question 6

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.. Option B is correct because during failover, the DNS record is updated to point to the standby instance, which takes about 60 seconds for propagation. Option A is wrong because failover itself typically takes 60-120 seconds, not longer. Option C is wrong because RDS automatically manages failover without manual promotion. Option D is wrong because RDS handles failover without needing a new endpoint.

Answer

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

Answer

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

Answer

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

Question 7

A data engineer is designing a data lake on Amazon S3. The data is ingested from multiple sources in Parquet format, partitioned by date. The engineer needs to ensure that queries using Amazon Athena are cost-effective and perform well. Which approach should the engineer take?

Accepted Answer

Use Parquet format with Snappy compression and partition by year, month, day.. Option C is correct because partitioning and columnar storage reduce data scanned. Option A increases cost due to many small files. Option B is less efficient than Parquet. Option D compresses but doesn't partition.

Answer

Store data in uncompressed CSV format and partition by year, month, day, hour.

Answer

Use JSON format with Snappy compression and partition by date only.

Answer

Use Gzip-compressed CSV files with no partitioning.

Question 8

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.. Option C is correct because DynamoDB supports encryption at rest using AWS KMS customer managed keys. Option A is for S3. Option B is for RDS. Option D is not a DynamoDB feature.

Answer

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

Answer

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

Answer

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

Question 9

A data engineer is migrating an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB in size and has a tight migration window. Which migration approach minimizes downtime?

Accepted Answer

Use AWS DMS with ongoing replication to capture changes during migration.. Option D is correct because AWS DMS with ongoing replication allows minimal downtime. Option A is full dump and restore, causing downtime. Option B is slow. Option C requires manual setup.

Answer

Use AWS Database Migration Service (DMS) with full load only.

Answer

Use pg_dump to export the database and pg_restore to import into RDS.

Answer

Create a read replica in RDS and promote it when ready.

Question 10

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.. Option B is correct because analyzing query patterns helps choose optimal distribution. Option A changes all tables, which may not be ideal. Option C is for storage, not distribution. Option D is for sort keys.

Answer

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

Answer

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

Answer

Set all tables to DISTSTYLE EVEN to distribute data evenly.

Question 11

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. Option A is correct because DynamoDB is designed for high write throughput and low-latency reads. Option B (RDS) is relational and more expensive. Option C (ElastiCache) is in-memory and costly for large data. Option D (Redshift) is for analytics.

Answer

Amazon ElastiCache for Redis

Answer

Amazon RDS for MySQL

Answer

Amazon Redshift

Question 12

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.. Option A is correct because it covers all requirements. Option B allows public access via bucket policy. Option C uses HTTPS but doesn't enforce it. Option D doesn't enforce HTTPS or block public access.

Answer

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

Answer

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.

Question 13

A data engineer is designing a data store for a real-time leaderboard application that requires sub-millisecond read and write latency. The leaderboard stores scores for millions of users and needs to be sorted by score. Which AWS service should the engineer use?

Accepted Answer

Amazon ElastiCache for Redis with a sorted set. Option C is correct because ElastiCache for Redis with sorted sets provides sub-millisecond latency and sorted data. Option A (DynamoDB) is fast but not designed for sorted sets. Option B (RDS) is slower. Option D (Neptune) is graph database.

Answer

Amazon RDS for PostgreSQL with an index on score

Answer

Amazon DynamoDB with a global secondary index on score

Answer

Amazon Neptune with a graph model

Question 14

A data engineer needs to store archival data that is rarely accessed but must be retained for 7 years. The data should be retrievable within 12 hours. Which Amazon S3 storage class is MOST cost-effective?

Accepted Answer

S3 Glacier Deep Archive. Option C is correct because Glacier Deep Archive is the cheapest storage class with retrieval within 12 hours. Option A (Standard) is expensive. Option B (Glacier Flexible Retrieval) is more expensive. Option D (Intelligent-Tiering) may not archive automatically.

Answer

S3 Intelligent-Tiering

Answer

S3 Glacier Flexible Retrieval

Answer

S3 Standard

Question 15

Which TWO actions can help improve the read performance of an Amazon DynamoDB table that is experiencing throttling? (Choose two.)

Accepted Answer

Increase the provisioned read capacity units (RCUs) for the table.. Options A and D are correct. Adding a GSI distributes read load, and increasing read capacity directly addresses throttling. Option B is for writes. Option C reduces latency but not throttling. Option E is for cost reduction.

Answer

Enable DynamoDB Accelerator (DAX) for write-heavy workloads.

Answer

Use eventually consistent reads instead of strongly consistent reads.

Answer

Enable auto-scaling with a lower minimum capacity.