DEA-C01 Data Store Management Practice Test 19 — 15 Questions

Question 1

A data engineer needs to store JSON documents that are frequently read and written by a web application. The data has a flexible schema and requires low-latency queries on primary key lookups. Which AWS service is MOST suitable?

Accepted Answer

Amazon DynamoDB. Option B is correct because DynamoDB is a NoSQL database designed for low-latency key-value lookups with flexible schema. Option A is wrong because RDS is relational and requires fixed schema. Option C is wrong because S3 is object storage, not designed for low-latency primary key lookups. Option D is wrong because Redshift is a data warehouse for analytics, not transactional workloads.

Answer

Amazon Redshift

Answer

Amazon S3

Answer

Amazon RDS for MySQL

Question 2

A company runs a critical transactional database on Amazon RDS for PostgreSQL. They need to achieve high availability with automatic failover to a different AWS Region in case of a regional outage. Which solution meets these requirements?

Accepted Answer

Use Amazon Aurora Global Database with a primary cluster in one Region and a secondary in another.. Option D is correct because Amazon Aurora Global Database provides cross-region replication with failover capabilities. Option A is wrong because Multi-AZ only protects against AZ failures, not regional. Option B is wrong because Read Replicas are for read scaling, not automatic failover. Option C is wrong because manual snapshot restore takes too long for high availability.

Answer

Create a cross-Region Read Replica and promote it during a disaster.

Answer

Take daily automated snapshots and restore them in another Region.

Answer

Deploy the RDS instance in a Multi-AZ configuration.

Question 3

A data engineer is designing a data lake on Amazon S3. The data is ingested from multiple sources in Parquet format, and the schema evolves over time. Which approach allows querying the data with Amazon Athena while supporting schema evolution?

Accepted Answer

Use AWS Glue Data Catalog with crawlers to automatically update the table schema.. AWS Glue Data Catalog with crawlers automatically infers and updates the table schema as new Parquet files with evolving schemas are ingested into S3. This allows Athena to query the data using the latest schema without manual intervention, making it the ideal solution for schema evolution in a data lake.

Answer

Define Hive-style partitions in Athena and manually update the schema.

Answer

Use S3 Select to query the data directly without a schema.

Answer

Use Amazon Redshift Spectrum with external tables and update the schema manually.

Question 4

A company needs to store relational data that requires complex joins and transactional consistency. The workload is predictable and the data size is less than 500 GB. Which AWS service is MOST cost-effective for this use case?

Accepted Answer

Amazon RDS for PostgreSQL. Option B is correct because Amazon RDS provides managed relational databases with support for complex joins and transactions. Option A is wrong because DynamoDB is NoSQL and does not support complex joins. Option C is wrong because Redshift is for analytics and is overkill for 500 GB. Option D is wrong because S3 is not a relational database.

Answer

Amazon Redshift

Answer

Amazon S3

Answer

Amazon DynamoDB

Question 5

A company uses Amazon DynamoDB for a gaming leaderboard. The table has a partition key of 'GameId' and a sort key of 'Score'. The application needs to query the top 10 scores for a given game. Which DynamoDB feature should be used for optimal performance?

Accepted Answer

Create a Global Secondary Index with the same partition key and sort key, then query with ScanIndexForward false.. Option C is correct because a Global Secondary Index with 'GameId' as partition key and 'Score' as sort key allows efficient querying with ScanIndexForward=false to get top scores. Option A is wrong because the base table's sort key is 'Score', but querying by 'GameId' and sorting descending would work but is less efficient if the table has other attributes. However, GSI is specifically for this access pattern. Option B is wrong because DynamoDB Streams is for change data capture, not querying. Option D is wrong because DAX is a caching layer, not a querying feature.

Answer

Use a Query operation on the base table with ScanIndexForward set to false.

Answer

Enable DynamoDB Streams and use a Lambda function to compute the leaderboard.

Answer

Use DynamoDB Accelerator (DAX) to cache the results of a Scan operation.

Question 6

A company is migrating an on-premises Hadoop cluster to AWS. The cluster processes large files in CSV format using Apache Spark. Which data store should be used as the primary storage for the data lake to optimize cost and performance?

Accepted Answer

Amazon S3. Option C is correct because Amazon S3 is the best choice for data lake storage due to its durability, scalability, and cost-effectiveness. Option A is wrong because EBS is block storage for EC2 instances, not suitable for large-scale data lakes. Option B is wrong because EMRFS is a connector for S3, not a separate storage. Option D is wrong because RDS is relational and not designed for large file storage.

Answer

Amazon EMR File System (EMRFS) backed by HDFS

Answer

Amazon RDS for MySQL

Answer

Amazon EBS volumes attached to the EMR cluster

Question 7

A company has an Amazon Redshift cluster with a mix of frequently accessed hot data and rarely accessed cold data. They want to reduce storage costs without affecting query performance for the hot data. Which strategy is MOST effective?

Accepted Answer

Use RA3 nodes with managed storage to automatically offload cold data to Amazon S3.. RA3 nodes with managed storage automatically separate compute and storage, offloading cold data to Amazon S3 while keeping hot data on local SSD for fast queries. This reduces storage costs without manual intervention or affecting hot data performance.

Answer

Reduce the number of nodes and increase the number of slices.

Answer

Create external tables in Redshift Spectrum to query cold data in S3.

Answer

Use Dense Compute nodes and unload cold data to Amazon S3 manually.

Question 8

A company needs to store archival logs that must be retained for 10 years. The logs are accessed infrequently, but when accessed, retrieval must occur within 12 hours. Which storage class is MOST cost-effective?

Accepted Answer

Amazon S3 Glacier Deep Archive. Option D is correct because S3 Glacier Deep Archive is the lowest-cost storage class with retrieval times within 12 hours. Option A is wrong because S3 Standard is expensive for long-term archival. Option B is wrong because S3 Intelligent-Tiering is designed for unknown access patterns, not pure archival. Option C is wrong because S3 One Zone-IA is less durable and not cost-effective for 10-year retention due to frequent access fees if retrieved.

Answer

Amazon S3 Intelligent-Tiering

Answer

Amazon S3 Standard

Answer

Amazon S3 One Zone-Infrequent Access

Question 9

A company is using Amazon S3 to store sensitive financial data. They need to ensure that all objects are encrypted at rest. Which TWO methods can achieve this? (Choose TWO.)

Accepted Answer

Use SSE-KMS to encrypt objects with AWS KMS.. Options A and B are correct. SSE-S3 and SSE-KMS both provide encryption at rest. Option C is wrong because client-side encryption is not managed by S3. Option D is wrong because bucket policies do not enforce encryption; they require encryption. Option E is wrong because S3 Transfer Acceleration is for speed, not encryption.

Answer

Enable S3 Transfer Acceleration on the bucket.

Answer

Apply a bucket policy that denies PutObject without encryption.

Answer

Use client-side encryption before uploading objects.

Question 10

A company is designing a multi-Region disaster recovery solution for Amazon DynamoDB. They need to ensure that data is replicated across Regions with minimal latency and that applications can read from any Region. Which THREE steps should be taken? (Choose THREE.)

Accepted Answer

Configure application to read from any Region using the DynamoDB endpoint.. Options A, C, and E are correct. Global Tables replicate data across Regions. DynamoDB Streams capture changes for replication. Applications can read from any Region. Option B is wrong because DAX is not required for global replication. Option D is wrong because TTL is for expiration, not replication.

Answer

Configure Time to Live (TTL) to automatically expire old data.

Answer

Deploy DynamoDB Accelerator (DAX) in each Region.

Question 11

A company is using Amazon RDS for MySQL and wants to automate backups for point-in-time recovery. Which TWO actions should be taken? (Choose TWO.)

Accepted Answer

Enable automated backups with a retention period.. Options B and D are correct. Automated backups are enabled by default, and the retention period can be set up to 35 days. Option A is wrong because manual snapshots are not automated. Option C is wrong because Multi-AZ is for high availability, not backups. Option E is wrong because AWS Backup is an optional service but not required; RDS native backups suffice.

Answer

Use AWS Backup to schedule backups.

Answer

Enable Multi-AZ deployment.

Answer

Take manual snapshots daily.

Question 12

Refer to the exhibit. A data engineer configured the lifecycle policy shown. The 'logs/' prefix contains important audit logs. After 365 days, what happens to the objects?

Accepted Answer

Objects are permanently deleted.. Option D is correct because the expiration action deletes objects after 365 days. Option A is wrong because the policy transitions to Glacier, not Deep Archive. Option B is wrong because the transition to Standard IA occurs at 30 days, not 365. Option C is wrong because the transition to Glacier occurs at 90 days, not 365.

Answer

Objects are transitioned to Glacier Deep Archive.

Answer

Objects are transitioned to Glacier.

Answer

Objects are transitioned to Standard-IA.

Question 13

Refer to the exhibit. An IAM policy is attached to an IAM role used by an application. The application needs to decrypt objects in an S3 bucket using a customer managed KMS key. What is the effect of this policy?

Accepted Answer

The application can decrypt objects only when accessing them through S3.. The IAM policy grants the `kms:Decrypt` permission with a `kms:ViaService` condition key set to `s3.amazonaws.com`. This condition restricts the decryption operation to only when the request is made through the S3 service. Therefore, the application can decrypt objects only when accessing them through S3, not via direct KMS API calls or other services.

Answer

The application cannot perform any KMS operations.

Answer

The application can decrypt objects from any service.

Answer

The application can encrypt but not decrypt objects.

Question 14

Refer to the exhibit. A data engineer notices that the Redshift cluster 'mycluster' does not have automated backups beyond 7 days. However, the compliance team requires a minimum of 35 days of backup retention. What should the engineer do?

Accepted Answer

Modify the cluster's automated snapshot retention period to 35 days.. Option D is correct because Amazon Redshift allows you to modify the automated snapshot retention period for a cluster up to 35 days. The engineer can use the AWS Management Console, CLI, or API to change the `automated_snapshot_retention_period` parameter from the current 7 days to 35 days, meeting the compliance requirement without additional manual intervention.

Answer

Change the node type to ra3.xlplus to enable automatic backups for 35 days.

Answer

Enable audit logging to capture changes for recovery.

Answer

Take manual snapshots every day and retain them for 35 days.

Question 15

A company stores sensitive data in an S3 bucket. To meet compliance requirements, they must ensure that all objects are encrypted at rest using server-side encryption with AWS KMS. Which bucket policy statement should be applied to deny uploads that do not use the required encryption?

Accepted Answer

{"Effect":"Deny","Principal":"*","Action":"s3:PutObject","Resource":"arn:aws:s3:::bucketname/*","Condition":{"StringNotEquals":{"s3:x-amz-server-side-encryption":"aws:kms"}}}. Option D is correct because the condition 's3:x-amz-server-side-encryption': 'aws:kms' ensures that only objects encrypted with SSE-KMS are allowed. Option A uses SSE-S3, which is not KMS. Option B uses the wrong header. Option C uses SSE-C, which is not allowed. Option D correctly denies if the encryption is not 'aws:kms'.

Answer

{"Effect":"Deny","Principal":"*","Action":"s3:PutObject","Resource":"arn:aws:s3:::bucketname/*","Condition":{"StringNotEquals":{"s3:x-amz-server-side-encryption":"AES256"}}}

Answer

{"Effect":"Deny","Principal":"*","Action":"s3:PutObject","Resource":"arn:aws:s3:::bucketname/*","Condition":{"StringNotEquals":{"s3:x-amz-server-side-encryption-aws-kms-key-id":"arn:aws:kms:us-east-1:123456789012:key/abc123"}}}

Answer

{"Effect":"Deny","Principal":"*","Action":"s3:PutObject","Resource":"arn:aws:s3:::bucketname/*","Condition":{"Null":{"s3:x-amz-server-side-encryption":"true"}}}