DEA-C01 Data Store Management Practice Test 6 — 15 Questions

Question 1

A company is migrating its on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB in size and has a 24-hour maintenance window. The migration must have minimal downtime. Which AWS service should be used for the migration?

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

Accepted Answer

AWS Database Migration Service (DMS). AWS Database Migration Service (DMS) is the correct choice because it supports heterogeneous migrations (Oracle to RDS for Oracle) with minimal downtime using ongoing replication via Oracle LogMiner or binary reader. DMS can perform a full load of the 2 TB database and then continuously replicate changes from the source to the target during the 24-hour maintenance window, allowing a final cutover with only seconds of downtime.

Answer

Amazon RDS native backup and restore

Answer

Amazon S3 Transfer Acceleration

Answer

AWS Snowball Edge

Question 2

A financial services company is designing a data store for transaction records that must be immutable and auditable. The data must be stored for 7 years. Which AWS services can be combined to meet these requirements? (Choose TWO.)

Accepted Answer

Amazon S3 Glacier Deep Archive. Option B, Amazon S3 with Object Lock enabled, is correct because S3 Object Lock provides WORM (write once, read many) protection, making objects immutable and preventing deletion or overwrite for a defined retention period, which directly satisfies the immutability and auditability requirements. Option A, Amazon S3 Glacier Deep Archive, is correct because it is the lowest-cost S3 storage class designed for long-term retention (default minimum 180 days) and can hold data for the required 7 years, and it can be used as the storage class for objects protected by Object Lock. Together, S3 Object Lock plus Glacier Deep Archive deliver immutable, auditable, cost-effective 7-year retention. Option C, Amazon EBS volume with snapshots, is not appropriate because EBS snapshots are mutable/deletable and EBS is block storage not designed for immutable long-term archival. Option D, Amazon RDS with automated backups, is not suitable because automated backups are retained for a limited period and can be deleted, and RDS does not provide WORM immutability. Option E, Amazon DynamoDB with point-in-time recovery, is not correct because PITR only allows restoring to any point in the last 35 days and does not enforce immutability or 7-year retention.

Answer

Amazon EBS volume with snapshots

Answer

Amazon RDS with automated backups

Answer

Amazon DynamoDB with point-in-time recovery

Question 3

A company uses Amazon DynamoDB for a gaming leaderboard. The table has a primary key of GameId (partition key) and Score (sort key). The application needs to retrieve the top 10 scores for a given game. Which strategies can improve query performance? (Choose TWO.)

Accepted Answer

Create a global secondary index with Score as sort key. Creating a global secondary index (GSI) with Score as the sort key allows efficient range queries on scores for a given GameId. DynamoDB can then use the GSI to retrieve the top 10 scores in sorted order without scanning the entire table, leveraging the index's sort key to fetch only the highest values.

Answer

Change the primary key to a single attribute

Answer

Use a Scan operation with a limit

Answer

Increase the write capacity units

Question 4

A data engineer is designing a data store for a real-time analytics application that requires sub-millisecond read and write latency. The data is accessed via a REST API. Which AWS services should the engineer consider? (Choose THREE.)

Accepted Answer

Amazon ElastiCache for Redis. Amazon ElastiCache for Redis (C) is correct because it is an in-memory data store that delivers sub-millisecond latency for both reads and writes, making it ideal for real-time analytics workloads. Amazon DynamoDB (D) is correct because it is a fully managed NoSQL key-value and document database designed for consistent single-digit millisecond latency at scale, and it can be accessed via REST APIs. DynamoDB Accelerator (E) is correct because DAX is an in-memory cache for DynamoDB that reduces read latency from milliseconds to microseconds, achieving sub-millisecond performance for read-heavy real-time applications. Amazon S3 (A) is not suitable because it is object storage with higher latency and is not designed for sub-millisecond read/write operations. Amazon RDS for MySQL (B) is not appropriate because it is a disk-based relational database that typically provides millisecond-level latency, not sub-millisecond, and is not optimized for the extreme low-latency requirements of real-time analytics.

Answer

Amazon S3

Answer

Amazon RDS for MySQL

Question 5

A data engineer runs the describe-table command shown in the exhibit. The application frequently queries by CustomerID alone. Currently, these queries result in full table scans. Which action should the engineer take to improve query performance?

Accepted Answer

Create a global secondary index on CustomerID. The `describe-table` output shows CustomerID is the partition key, but the application frequently queries by CustomerID alone, which currently causes full table scans because there is no index supporting that query pattern. Creating a global secondary index (GSI) on CustomerID allows efficient querying by CustomerID without scanning the entire table, as the GSI provides a separate data structure with its own read/write capacity that can be queried directly.

Answer

Change the sort key to OrderID

Answer

Create a local secondary index on CustomerID

Answer

Increase the read capacity units to 500

Question 6

A company uses Amazon RDS for MySQL with Multi-AZ deployment. During a recent failover, the application experienced a brief outage because it cached the old database endpoint. Which solution would minimize application disruption during future failovers?

Accepted Answer

Use the RDS cluster endpoint in the application configuration.. The RDS cluster endpoint (also known as the writer endpoint) automatically points to the primary instance in a Multi-AZ deployment. During a failover, DNS is updated to resolve the cluster endpoint to the new primary instance, so the application does not need to cache or change the endpoint. This minimizes disruption by ensuring the application always connects to the current primary without manual intervention.

Answer

Use Amazon ElastiCache to cache database queries and absorb the failover delay.

Answer

Create a read replica in another Availability Zone and promote it during failover.

Answer

Configure the application to connect using the RDS instance's private IP address.

Question 7

A data engineer needs to store time-series sensor data from thousands of IoT devices. The data is written once, read frequently for the last 24 hours, and rarely accessed after 30 days. Which storage solution is MOST cost-effective?

Accepted Answer

Amazon Timestream with a 30-day retention policy.. Amazon Timestream is purpose-built for time-series data, offering automatic storage tiering where recent data resides in memory for fast queries and historical data is moved to a cost-optimized magnetic store. A 30-day retention policy aligns perfectly with the requirement to keep data accessible for frequent reads over the last 24 hours while automatically expiring older data, minimizing storage costs without manual intervention.

Answer

Amazon Redshift with automatic compression and distribution keys.

Answer

Amazon DynamoDB with TTL to expire data after 30 days.

Answer

Amazon S3 with lifecycle policies to transition to S3 Glacier after 30 days.

Question 8

A data engineer notices that an Amazon Redshift cluster's storage utilization has grown unexpectedly. The cluster uses automatic compression and has a mix of fact and dimension tables. The engineer runs VACUUM and ANALYZE, but storage does not decrease. Which action is most likely to reduce storage consumption?

Accepted Answer

Perform a DEEP COPY on the largest tables.. DEEP COPY recreates the table with a fresh, optimally sorted and compressed storage layout, reclaiming space that VACUUM alone cannot recover. In Redshift, VACUUM reorganizes and reclaims space from deleted rows but does not re-apply compression or rebuild the underlying storage blocks; DEEP COPY (e.g., using CREATE TABLE AS or the DEEP COPY command) physically rewrites the data, eliminating fragmentation and applying the current compression encoding, which can significantly reduce storage consumption when automatic compression has left suboptimal encodings or when historical updates have bloated the table.

Answer

Run VACUUM with the BOOST option.

Answer

Run ANALYZE with the FULL keyword on all tables.

Answer

Modify the sort key on the largest tables to a more selective column.

Question 9

A company uses Amazon DynamoDB for a gaming application that requires single-digit millisecond read and write latencies. The application experiences throttling on the 'GameScores' table during peak hours. The table has a partition key of 'game_id' and a sort key of 'player_id'. The data engineer needs to improve performance without changing the table's provisioned capacity. Which THREE actions should the engineer take? (Choose THREE.)

Accepted Answer

Enable DynamoDB auto scaling to adjust capacity based on traffic patterns.. Option B is correct because DynamoDB auto scaling adjusts provisioned RCUs/WCUs in response to actual traffic patterns, which helps eliminate throttling during peak hours while still honoring the requirement not to manually change provisioned capacity. Option C is correct because adding a Global Secondary Index with a different partition key redistributes read traffic across additional partitions, reducing hot-partition pressure on the GameScores table and improving read performance. Option D is correct because DynamoDB Accelerator (DAX) is an in-memory cache that serves eventually consistent reads in microseconds, offloading repeated read requests from the table and reducing throttling on read-heavy gaming workloads. Option A is not correct because adaptive capacity is an automatic, always-on DynamoDB feature rather than an action the engineer must enable. Option E is not correct because increasing RCUs to twice the peak value changes the table's provisioned capacity, which the scenario explicitly forbids.

Answer

Enable DynamoDB adaptive capacity to allow more throughput per partition.

Answer

Increase the read capacity units (RCUs) to twice the peak observed value.

Question 10

A data engineer is migrating an on-premises Microsoft SQL Server database to Amazon RDS for SQL Server. The database is 2 TB in size and has a 4-hour maintenance window. The company needs to minimize downtime and ensure data consistency. Which TWO methods should the engineer use? (Choose TWO.)

Accepted Answer

Use AWS Database Migration Service (AWS DMS) with ongoing replication to minimize downtime.. Option A is correct because AWS DMS with ongoing (change data capture) replication performs a full load and then continuously applies ongoing changes from the source SQL Server to the RDS target, allowing the cutover to happen during the 4-hour maintenance window with minimal downtime while keeping data consistent. Option C is correct because RDS for SQL Server natively supports restoring a native backup (.bak) taken from an on-premises SQL Server into the RDS instance, which is a reliable, consistent way to migrate a large 2 TB database and can be combined with a short delta sync to fit the maintenance window. Option B is not appropriate because the SSMS Export Wizard is a manual, row-by-row client-side process that is impractical for a 2 TB database and does not provide ongoing replication or strong consistency guarantees. Option D is not appropriate because AWS SCT is designed for schema and code conversion between heterogeneous engines (for example, Oracle or SQL Server to PostgreSQL/MySQL), not for migrating a same-engine SQL Server database to RDS for SQL Server. Option E is not appropriate because exporting to CSV and using BULK INSERT is a slow, error-prone, manual approach that risks data inconsistency and cannot meet the minimal-downtime requirement for a 2 TB database.

Answer

Use SQL Server Management Studio (SSMS) export wizard to transfer data.

Answer

Use AWS Schema Conversion Tool (AWS SCT) to convert the schema and migrate data.

Answer

Export the database to CSV files and use BULK INSERT to load into RDS.

Question 11

A company stores sensitive customer data in Amazon S3. The security team requires that all objects be encrypted at rest using server-side encryption with customer-provided keys (SSE-C). Which bucket policy condition will enforce this requirement?

Accepted Answer

s3:x-amz-server-side-encryption-customer-key. The condition key `s3:x-amz-server-side-encryption-customer-key` is specifically used to enforce that objects uploaded to S3 must use server-side encryption with customer-provided keys (SSE-C). This condition key checks for the presence of the `x-amz-server-side-encryption-customer-key` header in the request, which is required for SSE-C encryption. Without this header, the request is denied, ensuring all objects are encrypted at rest using customer-provided keys.

Answer

s3:x-amz-server-side-encryption-aws-kms-key-id

Answer

s3:x-amz-server-side-encryption

Answer

s3:x-amz-server-side-encryption-customer-algorithm

Question 12

A data engineer needs to store semi-structured JSON data for a real-time analytics application. The data will be queried using SQL-like statements and must support high-speed ingestion with minimal latency. Which AWS service is best suited for this use case?

Accepted Answer

Amazon Kinesis Data Analytics. Amazon Kinesis Data Analytics is best suited because it natively processes streaming JSON data using SQL-like statements (via Kinesis Data Analytics for SQL applications) with sub-second latency, enabling real-time analytics on semi-structured data without requiring a separate storage layer for ingestion. It directly integrates with Kinesis Data Streams or Firehose for high-speed ingestion and supports in-application queries on JSON payloads using the `json_extract` function or schema discovery.

Answer

Amazon S3

Answer

Amazon Redshift

Answer

Amazon DynamoDB

Question 13

A company is running a MySQL database on Amazon RDS. The database size is 2 TB, and the company needs to migrate it to Amazon Aurora MySQL with minimal downtime. Which migration strategy is most appropriate?

Accepted Answer

Create an Aurora MySQL read replica from the RDS instance, then promote it.. Creating an Aurora MySQL read replica from the existing RDS MySQL instance allows the Aurora cluster to stay synchronized with the source using MySQL’s native binlog replication. Once the replica lag reaches zero, you can promote it to a standalone Aurora cluster with minimal downtime, typically just a few seconds to stop writes and redirect traffic. This approach avoids the lengthy export/import process and leverages Amazon’s managed replication for near-zero-downtime migration.

Answer

Use mysqldump to export the database and import it into Aurora.

Answer

Take a snapshot of the RDS instance and restore it as an Aurora cluster.

Answer

Use AWS Database Migration Service (DMS) with full load and ongoing replication.

Question 14

A company is using Amazon DynamoDB for a gaming application with high read and write throughput. The data engineer notices that the read latency is high during peak hours. The table has a partition key only (no sort key). The engineer wants to improve read performance by distributing reads across partitions more evenly. Which action should the engineer take?

Accepted Answer

Enable DynamoDB Accelerator (DAX).. DynamoDB Accelerator (DAX) is an in-memory cache that reduces read latency from single-digit milliseconds to microseconds by caching frequently accessed items. Since the issue is high read latency during peak hours and the table has only a partition key, DAX offloads reads from the underlying table, distributing the read load and improving response times without changing the table's key structure.

Answer

Increase the read capacity units of the table.

Answer

Add a sort key to the table.

Answer

Enable DynamoDB global tables.

Question 15

Which TWO options are valid ways to encrypt data at rest in Amazon S3? (Choose two.)

Accepted Answer

Server-Side Encryption with S3-Managed Keys (SSE-S3). Option C (Server-Side Encryption with S3-Managed Keys, SSE-S3) is correct because S3 encrypts objects at rest using AES-256 keys fully managed by Amazon S3, requiring only the x-amz-server-side-encryption: AES256 header or bucket default encryption. Option E (Server-Side Encryption with AWS KMS-Managed Keys, SSE-KMS) is correct because S3 encrypts objects at rest using AWS KMS customer master keys (CMKs), providing envelope encryption plus auditability via CloudTrail and granular key policies. Both are genuine data-at-rest encryption mechanisms applied to objects stored in S3 buckets. Option A (Client-Side Encryption) is not marked correct here because it encrypts data before upload on the client, so it is not an S3 server-side at-rest encryption method as scoped by this question. Option B (SSL/TLS Encryption) protects data in transit over HTTPS, not at rest. Option D (IAM Policy Encryption) is not a real encryption mechanism; IAM policies only control authorization and access, they do not encrypt data.

Answer

Client-Side Encryption

Answer

SSL/TLS Encryption

Answer

IAM Policy Encryption