DEA-C01 Data Store Management Practice Test 28 — 15 Questions

Question 1

A data engineer needs to store semi-structured JSON data that is accessed infrequently but requires immediate retrieval when needed. The data must be durable and cost-effective. Which Amazon S3 storage class should be used?

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

Accepted Answer

S3 Standard-IA. S3 Standard-IA is the correct choice because it offers the same durability and low-latency retrieval as S3 Standard but at a lower storage cost, making it ideal for infrequently accessed data that still needs immediate retrieval when requested. The scenario specifies 'infrequently accessed' and 'immediate retrieval,' which aligns with Standard-IA's design for data accessed less than once a month but with millisecond first-byte latency.

Answer

S3 Glacier

Answer

S3 Standard

Answer

S3 One Zone-IA

Question 2

A company uses Amazon DynamoDB with global tables in three AWS Regions. The data engineer needs to ensure that writes to the table in us-east-1 are replicated to other regions with minimal latency. Which DynamoDB feature should be used?

Accepted Answer

DynamoDB Global Tables. DynamoDB Global Tables is the correct feature because it provides multi-region, multi-master replication, automatically replicating writes from us-east-1 to other regions with sub-second latency. This is achieved through DynamoDB Streams and a last-writer-wins conflict resolution mechanism, ensuring data consistency across regions without requiring custom replication logic.

Answer

DynamoDB Time to Live (TTL)

Answer

DynamoDB Streams

Answer

DynamoDB Accelerator (DAX)

Question 3

Which TWO options are valid ways to reduce storage costs for an Amazon S3 data lake that stores historical data rarely accessed after 30 days? (Choose TWO.)

Accepted Answer

Create a lifecycle policy to transition objects to S3 Standard-IA after 30 days.. S3 Standard-IA (Infrequent Access) is designed for data accessed less frequently but requires rapid access when needed. Transitioning objects to Standard-IA after 30 days reduces storage costs compared to S3 Standard while maintaining low-latency retrieval, making it ideal for a data lake where historical data is rarely accessed after the first month.

Answer

Enable S3 Transfer Acceleration for all uploads.

Answer

Create a lifecycle policy to delete objects after 30 days.

Answer

Enable S3 Versioning to preserve all object versions.

Question 4

Which THREE factors should a data engineer consider when choosing between Amazon RDS and Amazon DynamoDB for a new application? (Choose THREE.)

Accepted Answer

Requirement for ACID transactions across multiple tables.. Amazon RDS (with engines like PostgreSQL or MySQL) supports ACID transactions across multiple tables, ensuring atomicity, consistency, isolation, and durability for complex operations. DynamoDB, while supporting transactions, is limited to a single AWS account and region, and its transactional API has constraints on item sizes and throughput, making RDS the better choice for multi-table ACID compliance.

Answer

Ability to encrypt data at rest.

Answer

Support for multi-region disaster recovery.

Question 5

Which TWO AWS services can be used to automatically back up an Amazon RDS for SQL Server DB instance? (Choose TWO.)

Accepted Answer

Amazon RDS automated backups. Amazon RDS automated backups are a built-in feature of RDS that automatically creates daily snapshots of the DB instance and backs up transaction logs every 5 minutes, enabling point-in-time recovery to any second within the retention period. This is the native, no-cost mechanism for backing up an RDS for SQL Server DB instance without additional configuration beyond setting the backup retention window.

Answer

AWS Database Migration Service (DMS)

Answer

AWS Data Pipeline

Answer

Amazon S3

Question 6

A company runs a streaming application on Amazon EC2 instances that writes data to an Amazon DynamoDB table (us-east-1). The data is later consumed by a reporting job that runs every hour. Recently, the reporting job has been failing with ProvisionedThroughputExceededException errors during peak hours. The DynamoDB table uses provisioned capacity with 1000 read capacity units (RCU) and 500 write capacity units (WCU). The reporting job performs scans and reads using eventually consistent reads. The application's write traffic is steady, but the reporting job's reads spike at the top of the hour. The data engineer needs to resolve the throughput exceptions without affecting the application's writes. Which solution should the data engineer implement?

Accepted Answer

Create a global secondary index (GSI) with enough RCU for the reporting job and have the job query the index instead of scanning the table.. The reporting job is failing due to ProvisionedThroughputExceededException because it performs full table scans, consuming read capacity from the table's provisioned RCU. Since the write traffic is steady and must not be affected, increasing the table's RCU (Option B) is not ideal because it would also allow more reads, potentially impacting writes if capacity is shared. Switching to on-demand (Option D) would eliminate throttling but could significantly increase costs and does not provide dedicated read capacity for the reporting job. A read replica (Option C) is not a native DynamoDB feature. Creating a global secondary index (GSI) with its own provisioned read capacity dedicated for the reporting job (Option A) offloads the read traffic from the main table, preventing interference with writes. The job can query the GSI with eventually consistent reads, effectively using the allocated RCU on the GSI without affecting the table's capacity.

Answer

Increase the table's RCU to 2000.

Answer

Create a read replica of the DynamoDB table in a different region.

Answer

Switch the table to on-demand capacity mode.

Question 7

A data engineer is managing an Amazon Redshift cluster used for analytics. The cluster has a single node of type dc2.large. The engineer notices that queries are slowing down as data volume grows. The cluster's disk space is at 70% usage. The engineer needs to improve query performance and accommodate future growth. The budget allows for moderate cost increase. Which action should the engineer take?

Accepted Answer

Add another dc2.large node to the cluster.. The dc2.large node is a dense compute node with limited storage. Adding another dc2.large node (option A) increases both compute capacity and storage, which directly addresses the slowdown and provides room for growth at a moderate cost. Option B (resizing to a single ds2.xlarge node) increases storage but may not improve compute performance proportionally, as ds2 nodes are dense storage. Option C (single ra3.xlplus with managed storage) separates compute and storage but still has a single compute endpoint, and the cost is higher. Option D (concurrency scaling) adds cost without resolving the single-node bottleneck. Therefore, option A is the best choice.

Answer

Resize the cluster to a single ds2.xlarge node.

Answer

Migrate the cluster to a single ra3.xlplus node with managed storage.

Answer

Enable concurrency scaling and maintain the current cluster.

Question 8

A company uses Amazon S3 to store images that are accessed by a web application. The application generates presigned URLs for users to download images. Recently, the application has been experiencing errors when generating presigned URLs for objects that were uploaded using multipart upload. The errors indicate that the presigned URL does not work. The data engineer needs to ensure that presigned URLs work for all objects, including those uploaded via multipart upload. What should the data engineer do?

Accepted Answer

Ensure that the IAM user or role used to generate the presigned URL has s3:GetObject permission for the object.. Presigned URLs work regardless of whether the object was uploaded via single-part or multipart upload. The error typically occurs because the IAM user or role used to generate the presigned URL lacks the s3:GetObject permission for the object. Option B is correct. Option A (changing signing algorithm) is unnecessary; SigV4 is the default and works for all cases. Option C (enabling versioning) does not affect presigned URL generation. Option D (re-uploading) is not required as multipart uploads do not break presigned URLs.

Answer

Use a different signing algorithm when generating the presigned URL.

Answer

Enable S3 Versioning on the bucket.

Answer

Re-upload the objects using single-part upload instead of multipart upload.

Question 9

A company runs a production Amazon RDS for MySQL database with Multi-AZ deployment. The database experiences high read latency during peak hours. The company wants to improve read performance with minimal application changes. Which solution should a data engineer recommend?

Accepted Answer

Create one or more read replicas in a different Availability Zone.. Creating read replicas in a different Availability Zone offloads read traffic from the primary DB instance, reducing read latency during peak hours. Read replicas in Amazon RDS for MySQL are asynchronous replicas that can serve SELECT queries, requiring minimal application changes (only a new connection endpoint). This directly addresses high read latency without altering the existing Multi-AZ setup.

Answer

Use Amazon DynamoDB Accelerator (DAX) as a caching layer.

Answer

Increase the DB instance size to a larger instance class.

Answer

Enable Multi-AZ on the existing instance.

Question 10

A data engineer needs to store semi-structured JSON data that is accessed infrequently but requires immediate retrieval when needed. The data must be durable and cost-effective. Which Amazon S3 storage class should be used?

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

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is the correct choice because it is a fully managed NoSQL key-value and document database that natively supports semi-structured JSON data, schema-less design, and automatic scaling. Its partition key (device ID) and sort key (timestamp) enable low-latency, single-millisecond queries by device ID and timestamp, making it ideal for high-throughput IoT log ingestion.

Answer

Amazon RDS for PostgreSQL

Answer

Amazon Redshift

Answer

Amazon S3

Question 11

Refer to the exhibit. A data engineer is troubleshooting an IAM policy attached to a user. The user reports that they cannot upload objects to the S3 bucket 'data-lake-bucket' unless they explicitly specify the 'x-amz-server-side-encryption' header with value 'AES256'. The engineer wants to modify the policy to allow uploads without requiring encryption headers, but still enforce encryption on the bucket itself. Which change should the engineer make?

Accepted Answer

Remove the entire Deny statement.. Removing the Deny statement eliminates the explicit denial that blocks uploads without the 'x-amz-server-side-encryption' header set to 'AES256'. The Allow statement already grants s3:PutObject, and by removing the Deny, users can upload without specifying encryption headers. The bucket's default encryption setting (e.g., AES256) will then automatically encrypt objects at rest, enforcing encryption without requiring the header in the request.

Answer

Remove the Condition block from the Allow statement.

Answer

Change the Condition in the Allow statement to use aws:kms instead of AES256.

Answer

Set the bucket's default encryption to AES256 and keep the policy unchanged.

Question 12

A company stores sensitive data in an Amazon S3 bucket. A compliance requirement mandates that all data must be encrypted at rest with a key that is automatically rotated every year. The company also needs to maintain an audit trail of who used the key. Which solution meets these requirements?

Accepted Answer

Use AWS KMS customer managed keys (SSE-KMS) with automatic key rotation enabled.. AWS KMS customer managed keys (SSE-KMS) with automatic key rotation enabled satisfies both requirements: it encrypts data at rest in S3 and automatically rotates the KMS key every year. Additionally, KMS integrates with AWS CloudTrail to log every API call (e.g., Decrypt, GenerateDataKey) that uses the key, providing an audit trail of who used the key and when.

Answer

Use customer-provided encryption keys (SSE-C) and rotate keys manually.

Answer

Use S3 managed keys (SSE-S3) and enable S3 server access logs.

Answer

Configure a bucket policy to enforce encryption using the 'aws:SecureTransport' condition.

Question 13

A company runs an Amazon Redshift cluster with 10 RA3 nodes. The data warehouse stores 50 TB of data. The company notices that queries are slow and the cluster's storage utilization is high. The data engineer needs to improve query performance and reduce storage costs without changing the cluster's node count. Which action should the engineer take?

Accepted Answer

Use Redshift Spectrum to offload historical data to Amazon S3 and query it in place.. Redshift Spectrum allows you to query data directly from Amazon S3 without loading it into the cluster. By offloading historical or less-frequently accessed data to S3, you reduce the storage utilization on the RA3 nodes, which frees up managed storage and can improve query performance. This approach also lowers storage costs because S3 is cheaper than Redshift managed storage, and it does not change the node count.

Answer

Change the distribution style of large tables to DISTSTYLE ALL.

Answer

Migrate the cluster to Dense Compute node types.

Answer

Enable concurrency scaling to handle more concurrent queries.

Question 14

A data engineer is designing a data lake on Amazon S3. The data lake will store raw data, transformed data, and curated datasets. The engineer needs to ensure that raw data is immutable (never overwritten or deleted) and that only authorized users can access the transformed data. Which combination of S3 features should the engineer use?

Accepted Answer

Enable S3 Object Lock in compliance mode on the raw data prefix and use bucket policies to restrict access to transformed data prefix.. S3 Object Lock in compliance mode enforces a write-once-read-many (WORM) model, preventing any user—including the root user—from overwriting or deleting raw data. Bucket policies then provide granular access control to restrict the transformed data prefix to authorized users only, meeting both immutability and access control requirements.

Answer

Use S3 Lifecycle policies to archive raw data to S3 Glacier and set bucket policies for transformed data.

Answer

Enable S3 Versioning and use S3 Access Points for each prefix.

Answer

Enable default encryption with SSE-KMS and use S3 bucket policies to restrict access.

Question 15

A company uses Amazon DynamoDB to store session data for a web application. The application experiences throttling errors during peak traffic. The data engineer observes that the table's read capacity is consistently at 100% and the write capacity is at 20%. The engineer needs to resolve the throttling with minimal cost. Which solution should the engineer implement?

Accepted Answer

Implement DynamoDB Accelerator (DAX) to cache read-heavy workloads.. The issue is read-heavy throttling with read capacity at 100% while write capacity is low. Implementing DynamoDB Accelerator (DAX) provides an in-memory cache that offloads read traffic from the table, reducing read capacity consumption and eliminating throttling without increasing provisioned capacity. This is the most cost-effective solution as it avoids scaling costs and leverages caching for repeated reads.

Answer

Increase the provisioned read capacity units for the table.

Answer

Enable DynamoDB auto scaling for read capacity.

Answer

Decrease the provisioned write capacity units to free up budget for reads.