DEA-C01 Data Store Management Practice Test 20 — 15 Questions

Question 1

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.. Enabling automated backups in Amazon RDS for MySQL allows point-in-time recovery (PITR) to any second within the retention period. Option C is correct because setting the backup retention period to the desired number of days (1–35 days) defines how far back you can perform PITR, and it must be explicitly configured to enable automated backups.

Answer

Use AWS Backup to schedule backups.

Answer

Enable Multi-AZ deployment.

Answer

Take manual snapshots daily.

Question 2

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.. The lifecycle policy shown has a single rule that expires objects in the 'logs/' prefix after 365 days. In Amazon S3, an 'expiration' action permanently deletes the objects once the specified number of days has passed since object creation. There is no transition action configured, so objects are not moved to any storage class; they are simply deleted.

Answer

Objects are transitioned to Glacier Deep Archive.

Answer

Objects are transitioned to Glacier.

Answer

Objects are transitioned to Standard-IA.

Question 3

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 4

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.. 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 5

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"}}}. It uses the `s3:x-amz-server-side-encryption` condition key with `StringNotEquals` set to `aws:kms`, which denies any `s3:PutObject` request where the encryption header does not specify `aws:kms`. This ensures all uploaded objects are encrypted at rest using server-side encryption with AWS KMS, meeting the compliance requirement.

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"}}}

Question 6

A data engineer is designing a data lake on Amazon S3. The data is accessed frequently for the first 30 days, then rarely accessed after 90 days, and must be archived after 1 year. Which S3 lifecycle policy configuration meets these requirements with the lowest cost?

Accepted Answer

Transition to S3 Standard-IA after 30 days, then to S3 Glacier Deep Archive after 365 days.. It transitions data to S3 Standard-IA after 30 days (when frequent access drops), then to S3 Glacier Deep Archive after 365 days for archival, minimizing cost while meeting all access patterns. Standard-IA offers lower storage cost than Standard for infrequent access, and Glacier Deep Archive is the cheapest storage class for long-term archival.

Answer

Transition to S3 One Zone-IA after 30 days, then to S3 Glacier Deep Archive after 365 days.

Answer

Transition to S3 Glacier Flexible Retrieval after 90 days.

Answer

Transition to S3 Glacier Instant Retrieval after 30 days, then expire after 365 days.

Question 7

A company uses Amazon Redshift for its data warehouse. The data engineering team notices that queries against a large fact table are slow. The table is distributed using DISTSTYLE EVEN and has multiple sort keys. After analyzing the query plans, they find that most queries filter on a specific column, 'customer_id'. Which change would most likely improve query performance for these filter operations?

Accepted Answer

Change to DISTSTYLE KEY on the 'customer_id' column.. Changing to DISTSTYLE KEY on 'customer_id' ensures that rows with the same customer_id are co-located on the same node slice. This allows the Redshift query engine to perform filter operations on a single slice rather than scanning all slices, dramatically reducing data movement and improving query performance for queries that filter on that column.

Answer

Add a secondary sort key on 'customer_id'.

Answer

Change to DISTSTYLE EVEN with a different sort key.

Answer

Change to DISTSTYLE ALL for the fact table.

Question 8

A data engineer needs to migrate an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB and has a continuous stream of write operations. The migration should minimize downtime. Which AWS service should be used?

Accepted Answer

AWS Database Migration Service (DMS). AWS Database Migration Service (DMS) is the correct choice because it supports ongoing replication (change data capture) from an on-premises PostgreSQL source to Amazon RDS for PostgreSQL, enabling a near-zero downtime migration. DMS can handle the 2 TB dataset and continuous write stream by performing a full load followed by continuous replication of changes until the cutover. Other services lack the ability to perform live, transactional replication with minimal interruption.

Answer

AWS DataSync

Answer

AWS Snowball Edge

Answer

AWS Glue

Question 9

A company uses Amazon DynamoDB for a gaming application. The table has a partition key of 'user_id' and a sort key of 'game_timestamp'. The application frequently queries by 'user_id' and filters by 'game_timestamp' within a specific date range. The queries are slow. The table has a global secondary index (GSI) on 'game_timestamp'. What is the most likely cause of the slow queries?

Accepted Answer

A hot partition exists due to uneven access pattern on 'user_id'.. The slow queries are most likely caused by a hot partition on the base table. Even though the query uses 'user_id' as the partition key, if a small number of 'user_id' values receive a disproportionate amount of traffic, those specific partitions become overloaded, causing throttling and high latency. The GSI on 'game_timestamp' is not used for these queries because the filter is on the sort key of the base table, and DynamoDB can efficiently query by partition key and filter by sort key without needing a GSI.

Answer

The GSI has insufficient read capacity.

Answer

The GSI is used instead of the base table for queries on 'user_id'.

Answer

The sort key is not used in the query.

Question 10

A data engineer needs to store semi-structured JSON data that is accessed infrequently but requires millisecond retrieval latency. The data is immutable once written. Which AWS service is most cost-effective?

Accepted Answer

Amazon S3 (Standard-IA) with S3 Select. Amazon S3 Standard-IA with S3 Select is the most cost-effective choice because it provides infrequent access storage at low cost while S3 Select enables server-side filtering to retrieve only the required subset of JSON data, achieving millisecond latency for small queries on immutable data without the overhead of a full database.

Answer

Amazon DynamoDB with on-demand capacity

Answer

Amazon ElastiCache for Redis

Answer

Amazon RDS for PostgreSQL with JSONB

Question 11

A company runs a critical application on Amazon RDS for MySQL. To ensure high availability and automatic failover, the database is deployed as a Multi-AZ DB instance. The application uses read-heavy workloads. Which additional configuration should be used to offload read traffic without impacting write performance?

Accepted Answer

Create one or more Read Replicas in different AZs.. Amazon RDS Read Replicas are designed to offload read traffic from the primary DB instance without affecting write performance. Unlike the Multi-AZ standby instance, which is not accessible for reads, Read Replicas can be placed in different Availability Zones and serve read queries independently, improving read scalability while the primary handles writes.

Answer

Use the Multi-AZ standby instance for read queries.

Answer

Use Amazon ElastiCache to cache read queries.

Answer

Change to a Single-AZ deployment with a larger instance size.

Question 12

A data engineer is troubleshooting an Amazon Redshift cluster that has been experiencing slow query performance. The engineer checks the system tables and finds that many queries are waiting on 'wlm_queued' time. The cluster has 10 nodes and uses automatic WLM. What is the most likely cause?

Accepted Answer

The number of concurrent queries exceeds the available query slots.. When queries show 'wlm_queued' time in Amazon Redshift, it indicates they are waiting in the Workload Management (WLM) queue before execution. With automatic WLM, the system dynamically manages concurrency, but if the number of concurrent queries exceeds the available query slots (determined by the cluster's memory and concurrency scaling settings), queries will be queued. This is the most direct cause of 'wlm_queued' wait events, as WLM queues queries when all slots are occupied.

Answer

Network bandwidth saturation between nodes.

Answer

Sorting operations are too expensive.

Answer

Insufficient disk space on the cluster.

Question 13

A company uses Amazon S3 to store large datasets. The data engineering team needs to provide access to specific objects in the bucket to external partners using presigned URLs. Each URL should expire after 12 hours. The team wants to ensure that the presigned URLs cannot be used to access other objects in the bucket. Which approach should be taken?

Accepted Answer

Generate presigned URLs using the AWS SDK, specifying the exact object key and expiration time.. Presigned URLs generated via the AWS SDK allow you to specify the exact object key and expiration time, ensuring that the URL grants access only to that specific object for the defined 12-hour period. This approach uses the secret key of the IAM user or role to sign the URL, and the signature is tied to the object key, so the URL cannot be reused to access other objects in the bucket.

Answer

Create an IAM role for each partner and attach a policy that grants access to specific objects.

Answer

Use a bucket policy that allows access only from the partner's IP address range.

Answer

Use CloudFront signed URLs with a custom policy that restricts access to specific objects.

Question 14

Which TWO of the following are valid approaches to implement fine-grained access control for Amazon DynamoDB items based on user attributes? (Choose 2.)

Accepted Answer

Use Amazon Cognito identity pools with IAM roles that include conditions based on user attributes.. Amazon Cognito identity pools can be configured to assume IAM roles with fine-grained policies that use condition keys such as `dynamodb:LeadingKeys` or custom attribute-based conditions. This allows access to DynamoDB items to be restricted based on user-specific attributes (e.g., user ID) without hardcoding permissions per user.

Answer

Enable row-level security in DynamoDB using AWS Lake Formation.

Answer

Configure a VPC endpoint with a bucket policy to restrict access to specific items.

Answer

Store user-specific items in separate S3 buckets and use IAM policies to restrict bucket access.

Question 15

Which THREE of the following are best practices for managing data storage costs in Amazon S3? (Choose 3.)

Accepted Answer

Use S3 Lifecycle policies to transition objects to S3 Glacier Deep Archive after a specified period.. S3 Lifecycle policies allow you to automatically transition objects to lower-cost storage classes like S3 Glacier Deep Archive after a specified period, reducing storage costs for infrequently accessed data. Option C is correct because combining S3 Object Lock with a lifecycle policy to expire objects after the retention period ensures that objects are automatically deleted when they are no longer needed, preventing unnecessary storage costs. Option E is correct because S3 Intelligent-Tiering automatically moves data between access tiers based on changing patterns, optimizing costs without manual intervention. Options A and D are not best practices for cost management: storing all data in S3 Standard is costly, and creating multiple replicas increases storage costs.

Answer

Store all data in S3 Standard for maximum durability.

Answer

Create multiple bucket replicas in different regions to ensure availability.