DEA-C01 Data Store Management Practice Test 29 — 15 Questions

Question 1

A company runs an Amazon RDS for PostgreSQL instance that stores financial data. The company requires point-in-time recovery (PITR) with a retention period of 35 days. Additionally, the company needs to create a new database from a specific snapshot every night for testing. Which combination of actions should the data engineer take to meet these requirements?

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

Accepted Answer

Enable automated backups with a 35-day retention period and create a manual snapshot each night for testing.. Automated backups in Amazon RDS for PostgreSQL support a maximum retention period of 35 days, which satisfies the PITR requirement. Additionally, creating a manual snapshot each night provides a stable, independent copy for testing without interfering with the automated backup schedule or the source database's performance.

Answer

Create a read replica and promote it to a new instance for testing each night.

Answer

Enable Multi-AZ and use the standby instance for testing.

Answer

Disable automated backups to reduce storage costs and take manual snapshots with 35-day retention.

Question 2

A data engineer needs to store log files from multiple applications in a central S3 bucket. The logs must be stored cost-effectively for long-term retention (7 years). The logs are accessed infrequently after the first 30 days. Which storage class should the engineer use for objects older than 30 days?

Accepted Answer

S3 Standard-IA. D is correct because S3 Standard-IA (Infrequent Access) is designed for data accessed less frequently but requires rapid access when needed, with a lower storage cost than S3 Standard and a 30-day minimum storage duration charge. After the first 30 days, logs are infrequently accessed, making Standard-IA the most cost-effective option that still provides millisecond first-byte latency for occasional retrieval needs over the 7-year retention period.

Answer

S3 Glacier Deep Archive

Answer

S3 Standard

Answer

S3 One Zone-IA

Question 3

A data engineer is designing a data store for a real-time analytics application that requires sub-millisecond read and write latency for time-series data. The data volume is expected to grow to hundreds of terabytes. Which TWO AWS services should the engineer consider? (Choose TWO.)

Accepted Answer

Amazon DynamoDB with Time-to-Live (TTL). Amazon DynamoDB with TTL is correct because it provides single-digit millisecond read and write latency at any scale, making it suitable for real-time time-series data. The TTL feature automatically expires old records, which helps manage the hundreds of terabytes of data without manual intervention, keeping storage costs predictable.

Answer

Amazon Redshift

Answer

Amazon ElastiCache for Redis

Answer

Amazon RDS for PostgreSQL

Question 4

A company has an S3 bucket with versioning enabled that stores critical data. The security team requires that once an object is deleted, it cannot be recovered by anyone, including the root user. Additionally, the company wants to ensure that objects cannot be overwritten for a specified period. Which THREE actions should the data engineer take to meet these requirements? (Choose THREE.)

Accepted Answer

Enable S3 Object Lock in compliance mode.. S3 Object Lock in compliance mode prevents objects from being deleted or overwritten by any user, including the root user, for the duration of the retention period. This meets the requirement that once an object is deleted, it cannot be recovered, because compliance mode locks are immutable and cannot be removed or shortened by anyone. Setting a retention period on the bucket using Object Lock ensures that objects cannot be overwritten for the specified period. Enabling S3 Versioning is necessary because Object Lock requires versioning to be enabled on the bucket to track object versions and enforce retention settings.

Answer

Enable MFA Delete on the bucket.

Answer

Configure a lifecycle policy to expire noncurrent versions after 1 day.

Question 5

Refer to the exhibit. A data engineer is analyzing a query performance issue on an Amazon Redshift table. The table 'sales' has 100 million rows. The query is performing a full table scan. Which optimization should the engineer apply to improve query performance?

Accepted Answer

Use a compound sort key on (sale_date, region).. The query is performing a full table scan, which indicates that Redshift cannot efficiently prune blocks. A compound sort key on (sale_date, region) orders rows by sale_date first, then by region, allowing Redshift to skip large portions of data when filtering on the leading column (sale_date). This minimizes the number of blocks scanned and dramatically improves query performance for range-based or equality filters on the leading column.

Answer

Change DISTKEY to region.

Answer

Use an interleaved sort key on (sale_date, region).

Answer

Change DISTSTYLE to ALL.

Question 6

A media company stores video files in an S3 bucket. The files are processed by a fleet of EC2 instances that read the files, add watermarks, and write the output back to the same bucket. Recently, the processing jobs have been failing with '500 Internal Server Error' and '503 Slow Down' errors. The data engineer checks the S3 bucket metrics and sees that the PUT/GET request rate is consistently above 5,500 requests per second for a single prefix. The engineer needs to resolve the errors with minimal changes to the application code. Which course of action should the engineer take?

Accepted Answer

Modify the application to add a random hash prefix to the object keys to distribute load across multiple prefixes.. S3 supports up to 5,500 GET/HEAD requests per second per prefix (and 3,500 PUT requests). By adding a random hash prefix to object keys, the load is distributed across multiple prefixes, effectively increasing the aggregate request rate limit. Option A (S3 Batch Operations) is designed for large-scale batch operations, not for real-time processing, and would not resolve the immediate request rate errors. Option B (increasing EC2 instances) would increase the request rate, potentially worsening the problem. Option C (S3 Transfer Acceleration) improves transfer speed over long distances but does not affect the per-prefix request rate limits.

Answer

Use S3 Batch Operations to process the files.

Answer

Increase the number of EC2 instances to process files in parallel.

Answer

Enable S3 Transfer Acceleration on the bucket to improve throughput.

Question 7

A financial services company has an Amazon DynamoDB table named 'Transactions' with provisioned read capacity of 10,000 RCU and write capacity of 5,000 WCU. The table stores transaction records for the past 90 days. The application performs point reads by transaction ID (partition key) and range queries by customer ID and timestamp (GSI). Recently, the company started a new marketing campaign, causing a sudden spike in write traffic. The write capacity is now at 4,500 WCU, and the application is experiencing occasional throttling on writes. The data engineer needs to ensure that writes are not throttled during future campaigns, while keeping costs low. The table currently has auto scaling enabled with a maximum capacity of 10,000 WCU. Which solution should the engineer implement?

Accepted Answer

Switch the table to DynamoDB on-demand capacity mode.. DynamoDB on-demand capacity mode automatically scales to accommodate traffic spikes, eliminating throttling without manual intervention and without fixed capacity limits, making it cost-effective for unpredictable traffic. Option B is wrong because DAX is a read cache and does not handle write throttling. Option C is wrong because using SQS adds latency and complexity; not ideal for real-time writes. Option D is wrong because increasing the maximum write capacity still has a limit and may not react quickly enough to sudden spikes, and may increase costs.

Answer

Use DynamoDB Accelerator (DAX) to cache write requests.

Answer

Implement an Amazon SQS queue to buffer write requests and process them in batches.

Answer

Increase the maximum write capacity in the auto scaling configuration to 20,000 WCU.

Question 8

A company runs an Amazon RDS for PostgreSQL instance that stores financial data. The company requires point-in-time recovery (PITR) with a retention period of 35 days. Additionally, the company needs to create a new database from a specific snapshot every night for testing. Which combination of actions should the data engineer take to meet these requirements?

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

Accepted Answer

Change the storage type to General Purpose SSD (gp3).. D is correct because gp3 storage provides a baseline performance that is higher than gp2 for the same storage size, and it allows you to independently provision IOPS and throughput without needing to increase storage. This directly addresses the write-intensive workload's high latency and storage bottleneck by offering up to 4,000 IOPS at no additional cost (compared to gp2's 3,000 IOPS baseline for larger volumes), and you can scale IOPS up to 16,000 without changing the instance class.

Answer

Create a read replica and offload writes to it.

Answer

Switch the storage type to Provisioned IOPS SSD (io1).

Answer

Enable Multi-AZ deployment for high availability.

Question 9

A company stores its application logs in an Amazon S3 bucket. The logs are accessed frequently for the first 30 days, after which they are rarely accessed but must be retained for 7 years for compliance. The company wants to optimize storage costs while maintaining immediate retrieval availability for the first 30 days and the ability to retrieve logs within 12 hours after that. Which lifecycle policy should the data engineer configure?

Accepted Answer

Transition objects to S3 Standard-IA after 30 days and then to S3 Glacier Deep Archive after 1 year.. It uses S3 Standard-IA for the first 30 days (frequent access, immediate retrieval) and then transitions to S3 Glacier Deep Archive after 1 year, which provides retrieval within 12 hours at the lowest cost for long-term retention. This meets the compliance requirement of 7-year retention while optimizing costs by moving data to progressively cheaper storage classes based on access patterns.

Answer

Delete objects after 30 days to minimize storage costs.

Answer

Transition objects to S3 One Zone-IA after 30 days and delete after 7 years.

Answer

Transition objects to S3 Glacier Flexible Retrieval after 30 days and delete after 7 years.

Question 10

A data engineering team is using Amazon DynamoDB to store user session data for a web application. The application experiences sudden spikes in traffic, causing throttling on the DynamoDB table. The team wants to minimize throttling without over-provisioning read/write capacity. Which solution should the team implement?

Accepted Answer

Enable DynamoDB Accelerator (DAX) caching layer.. DynamoDB Accelerator (DAX) is a fully managed, in-memory cache that reduces read latency from single-digit milliseconds to microseconds. By caching frequently accessed items, DAX offloads read requests from the DynamoDB table, directly reducing the read capacity consumption and thus minimizing throttling during traffic spikes without requiring over-provisioning of read capacity units.

Answer

Enable DynamoDB Time to Live (TTL) to automatically delete expired items.

Answer

Disable auto scaling and manually set a high provisioned capacity.

Answer

Use Amazon RDS read replicas to offload read traffic.

Question 11

A company uses Amazon S3 to store large datasets for analytics. Each dataset is stored in a separate prefix and consists of thousands of small objects (1-10 KB each). The company notices that listing objects in a prefix takes several seconds, slowing down data processing. Which solution would MOST improve listing performance?

Accepted Answer

Use S3 Inventory to generate a daily listing of objects.. S3 Inventory provides a scheduled CSV/Parquet file listing all objects in a bucket or prefix, including metadata like size and last modified date. By querying this inventory file instead of issuing real-time ListObject API calls, you avoid the latency of enumerating thousands of small objects, dramatically improving listing performance for analytics workflows.

Answer

Add a lifecycle policy to transition objects to S3 Glacier.

Answer

Use S3 Select to filter objects during listing.

Answer

Increase the number of parallel requests by using more prefixes.

Question 12

A company is migrating an on-premises MySQL database to Amazon RDS for MySQL. The database is 500 GB in size. The migration must have minimal downtime and must be completed within a week. Which AWS service should the data engineer use to perform 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. DMS can perform a full load of the 500 GB MySQL database and then continuously replicate ongoing changes from the on-premises source to the Amazon RDS target using change data capture (CDC), allowing the migration to complete within a week with near-zero downtime.

Answer

Amazon S3 Transfer Acceleration.

Answer

AWS Snowball Edge.

Answer

AWS DataSync.

Question 13

A data engineer needs to store clickstream data from a web application in Amazon S3. Each event is about 5 KB, and the application generates 1 million events per hour. The data is used for real-time analytics and also for batch processing. The engineer wants to minimize storage costs while ensuring that data is available for real-time queries as soon as it is written. Which storage class should the engineer use for the S3 bucket?

Accepted Answer

S3 Standard.. S3 Standard is the correct choice because it offers low-latency (milliseconds) first-byte-out performance, making data available for real-time queries immediately after writing. It also supports both real-time analytics and batch processing without retrieval fees, and at 5 KB per event with 1 million events per hour (approximately 5 GB/hour or 120 GB/day), the storage cost is manageable compared to the frequent access pattern. S3 Standard is optimized for frequently accessed data and provides the durability and availability needed for clickstream analytics.

Answer

S3 Intelligent-Tiering.

Answer

S3 Standard-IA.

Answer

S3 Glacier Instant Retrieval.

Question 14

A company uses Amazon DynamoDB to store metadata for a document management system. The table has a partition key of document_id and a sort key of version. The application frequently queries for the latest version of a document by document_id. The data engineer notices that these queries are consuming a lot of read capacity. How can the engineer optimize the read performance and reduce read capacity consumption?

Accepted Answer

Create a global secondary index (GSI) and use DynamoDB Accelerator (DAX).. Creating a Global Secondary Index (GSI) with document_id as the partition key and version as the sort key, combined with DynamoDB Accelerator (DAX), allows the application to query the latest version efficiently. The GSI can be configured to project only the necessary attributes, reducing read capacity consumption, while DAX provides an in-memory cache that offloads repeated read requests from the DynamoDB table, significantly lowering read capacity units (RCUs) consumed.

Answer

Change the sort key to store version in descending order.

Answer

Enable DynamoDB Streams and use a read replica.

Answer

Decrease the ReadCapacityUnits of the table to force caching.

Question 15

A data engineer is designing a data lake on Amazon S3 that will store sensitive financial data. The engineer needs to implement encryption at rest and ensure that only authorized users can access the data. Which TWO actions should the engineer take to meet these requirements? (Choose TWO.)

Accepted Answer

Configure a bucket policy that denies writes if the object is not encrypted.. A bucket policy with a condition that denies writes if the object is not encrypted (e.g., using `s3:x-amz-server-side-encryption` or `s3:PutObject` with `aws:SecureTransport`) enforces encryption at rest at the time of upload. This ensures that all objects written to the bucket are encrypted, meeting the encryption requirement without relying on client-side behavior.

Answer

Use server-side encryption with customer-provided keys (SSE-C).

Answer

Enable S3 Transfer Acceleration for the bucket.

Answer

Enable object-level access control lists (ACLs).