DEA-C01 Data Store Management Practice Test 8 — 15 Questions

Question 1

A data engineer needs to store event data from IoT devices that arrives in bursts. The data is key-value and requires single-digit millisecond read and write latency. The engineer also needs to run complex analytical queries on the data for reporting. Which TWO services should be used together? (Choose TWO.)

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is correct because it provides single-digit millisecond read and write latency at any scale, making it ideal for IoT event data arriving in bursts. Its key-value data model matches the requirement, and it can serve as the operational data store for fast ingestion while supporting complex analytical queries when integrated with Amazon Redshift.

Answer

Amazon ElastiCache for Redis

Answer

Amazon S3

Answer

Amazon RDS for MySQL

Question 2

A company is using Amazon S3 for a data lake. The data engineer needs to ensure that all new objects are automatically encrypted with a customer-managed KMS key and that the bucket policy enforces encryption. Which THREE steps should be taken? (Choose THREE.)

Accepted Answer

Configure default encryption on the bucket to use SSE-KMS.. Option A is correct because configuring default encryption on the S3 bucket to use SSE-KMS ensures that any object uploaded without an explicit encryption header is automatically encrypted with the specified customer-managed KMS key. This satisfies the requirement for automatic encryption of all new objects.

Answer

Use a lifecycle policy to apply encryption to existing objects.

Answer

Enable AWS CloudTrail to monitor encryption.

Question 3

A company uses Amazon RDS for MySQL with Multi-AZ deployment. The primary instance fails, and automatic failover occurs. After failover, the data engineer notices that the new primary instance has a different DNS endpoint. Which TWO statements are true about this scenario? (Choose TWO.)

Accepted Answer

The DNS CNAME record is updated to point to the new primary.. Option C is correct because when Amazon RDS performs automatic failover in a Multi-AZ deployment, it updates the DNS CNAME record for the primary DB instance to point to the new primary (formerly the standby). This ensures that applications using the original endpoint are transparently redirected to the new primary without manual intervention.

Answer

The standby instance is created in the same Availability Zone as the failed primary.

Answer

A manual DNS update is required to connect to the new primary.

Answer

The endpoint changes to the standby instance's endpoint.

Question 4

Refer to the exhibit. A data engineer is troubleshooting write throttling on the Orders table. The table has a composite primary key (OrderID as partition key, CustomerID as sort key). The engineer notices that writes are throttled even though the write capacity is not fully utilized. What is the most likely cause?

Accepted Answer

Writes are concentrated on a single partition key value.. D is correct because write throttling on an Amazon DynamoDB table occurs when requests exceed the provisioned throughput for a specific partition, even if the overall table write capacity is underutilized. With a composite primary key where OrderID is the partition key, writes concentrated on a single OrderID value (e.g., a hot key) will hit that partition's 3,000 WCU or 1,000 WCU (on-demand) limit, causing throttling while other partitions remain idle.

Answer

The table is empty and has no items.

Answer

A global secondary index (GSI) is consuming write capacity.

Answer

The read capacity units are too low.

Question 5

Refer to the exhibit. A data engineer has attached this bucket policy to an S3 bucket named data-lake-bucket. The engineer wants to allow only GET requests from the corporate network (10.0.0.0/16) over HTTPS. However, users report that they cannot access objects even when connected to the corporate network. What is the issue?

Accepted Answer

The Deny statement blocks all requests that are not using HTTPS, including those from the corporate network.. Option D is correct because the Deny statement with `aws:SecureTransport` set to `false` blocks all HTTP requests. Since the Allow statement only permits GET requests from the corporate network (10.0.0.0/16) but does not require HTTPS, any request from that network that uses HTTP is denied by the explicit Deny. The Deny statement overrides the Allow, so even legitimate corporate users are blocked if they use HTTP.

Answer

The Deny statement should include a condition on the source IP.

Answer

The Allow statement should include a condition for SecureTransport.

Answer

The Allow statement should specify s3:GetObject instead of s3:GetObject.

Question 6

Refer to the exhibit. A data engineer needs to connect to the Redshift cluster from an EC2 instance in the same VPC. The engineer can ping the EC2 instance but cannot connect to Redshift using the endpoint address and port 5439. What is the most likely cause?

Accepted Answer

The security group for the Redshift cluster does not allow inbound traffic on port 5439 from the EC2 instance.. The most likely cause is that the security group associated with the Redshift cluster does not have an inbound rule allowing TCP traffic on port 5439 from the security group or IP address of the EC2 instance. Since the engineer can ping the EC2 instance (ICMP works), but cannot connect to Redshift on port 5439, this points to a firewall or security group rule blocking the specific port, not a network reachability issue.

Answer

The Redshift cluster is in a different VPC.

Answer

The Redshift cluster is not in an available state.

Answer

The Redshift cluster is publicly accessible and requires an internet gateway.

Question 7

A data engineer needs to store semi-structured JSON logs from multiple microservices in a cost-effective manner for ad-hoc querying using SQL. Which AWS service should be used?

Accepted Answer

Amazon Athena with data in S3. Amazon Athena is the correct choice because it allows you to query semi-structured JSON logs stored in S3 directly using standard SQL, without needing to load or transform the data. Athena's schema-on-read approach and pay-per-query pricing make it highly cost-effective for ad-hoc analysis of large volumes of log data, as you only pay for the data scanned during queries.

Answer

Amazon DynamoDB

Answer

Amazon RDS for MySQL

Answer

Amazon Kinesis Data Analytics

Question 8

A company uses Amazon S3 as its data lake. A data engineer needs to enforce encryption of data at rest using server-side encryption with AWS KMS. Which S3 bucket property should be configured?

Accepted Answer

Default encryption. Option A is correct because configuring default encryption on an S3 bucket ensures that all objects stored in the bucket are encrypted at rest using server-side encryption. When AWS KMS is specified as the encryption type, S3 automatically encrypts objects with a KMS key (SSE-KMS) upon upload, even if the upload request does not include encryption headers. This enforces encryption at rest without requiring changes to client applications.

Answer

Server access logging

Answer

Versioning

Answer

Bucket policy

Question 9

A data engineer notices that an Amazon Redshift cluster’s storage usage is increasing rapidly due to many UPDATE and DELETE operations. The engineer needs to reclaim storage space and improve query performance. Which action should be taken?

Accepted Answer

Run VACUUM command. The VACUUM command in Amazon Redshift reclaims disk space occupied by deleted or updated rows and re-sorts the data according to the table's sort keys. This directly addresses the storage increase from UPDATE/DELETE operations and improves query performance by restoring the physical order of rows, which reduces the number of blocks scanned.

Answer

UNLOAD the table to S3 and reload

Answer

Increase cluster node count

Answer

Run ANALYZE command

Question 10

A company wants to store historical financial data for 7 years with immediate access for the first year and then infrequent access. After 7 years, the data must be automatically deleted. Which S3 lifecycle policy should be configured?

Accepted Answer

Transition to S3 Glacier Deep Archive after 365 days, expire after 2555 days. Option D is correct because it meets all requirements: immediate access for the first year (no transition before 365 days), then transition to S3 Glacier Deep Archive for infrequent access and cost savings, with automatic deletion after 7 years (2555 days). S3 Glacier Deep Archive is the most cost-effective storage class for long-term archival data that is rarely accessed, and the 2555-day expiration ensures compliance with the 7-year retention policy.

Answer

Transition to S3 Standard-IA after 30 days, expire after 2555 days

Answer

Transition to S3 Glacier Flexible Retrieval after 365 days, expire after 2555 days

Answer

Transition to S3 One Zone-IA after 90 days, expire after 365 days

Question 11

A data engineer is designing a data store for real-time analytics on high-velocity clickstream data. The data must be stored in a schema-on-read format and support SQL queries with sub-second latency. Which service should be used?

Accepted Answer

Amazon Kinesis Data Firehose to S3 with Athena. Amazon Kinesis Data Firehose can ingest high-velocity clickstream data and deliver it to Amazon S3, where it is stored in a schema-on-read format (e.g., Parquet or ORC). Amazon Athena then allows SQL queries directly on the data in S3 with sub-second latency when using partitions, columnar formats, and optimizations like AWS Glue Catalog. This combination meets the requirements for real-time analytics without predefining a schema.

Answer

Amazon Redshift

Answer

Amazon Kinesis Data Analytics

Answer

Amazon DynamoDB

Question 12

A data engineer is troubleshooting an Amazon Redshift cluster that is running out of disk space. The engineer runs STV_PARTITIONS and notices that some slices have significantly more data than others. What is the most likely cause and solution?

Accepted Answer

Data distribution skew due to uneven distribution style; change distribution style to EVEN or correct KEY. B is correct because STV_PARTITIONS shows per-slice disk usage, and significant variation indicates data distribution skew. Uneven distribution causes some slices to fill faster, leading to premature disk-full errors. Changing the distribution style to EVEN (for tables without join keys) or correcting the KEY distribution style (using a high-cardinality, evenly distributed column) rebalances data across slices.

Answer

Poorly chosen sort keys; redefine sort keys

Answer

Some nodes are underutilized; add more nodes

Answer

Concurrency scaling is disabled; enable concurrency scaling

Question 13

A data engineer needs to store transaction data that requires strong consistency, ACID transactions, and complex join queries. Which AWS service is most appropriate?

Accepted Answer

Amazon RDS for PostgreSQL. Amazon RDS for PostgreSQL is the most appropriate choice because it provides full ACID transaction support, strong consistency, and the ability to perform complex join queries using standard SQL. Unlike NoSQL or data warehouse solutions, PostgreSQL is a relational database that excels at enforcing referential integrity and supporting multi-table joins with advanced indexing.

Answer

Amazon DynamoDB

Answer

Amazon S3

Answer

Amazon Redshift

Question 14

A company has an S3 bucket with millions of objects. The data engineer needs to identify which objects are not accessed for 90 days to move them to a lower-cost storage class. Which feature should be used?

Accepted Answer

S3 Storage Class Analysis. S3 Storage Class Analysis (SCA) is the correct feature because it monitors access patterns across objects and provides recommendations for transitioning data to lower-cost storage classes based on last-access dates. SCA can analyze objects that have not been accessed for 90 days and generate a report to inform lifecycle policy creation, directly addressing the requirement to identify objects for cost optimization.

Answer

S3 Inventory

Answer

S3 Server Access Logs

Answer

S3 Event Notifications

Question 15

A data engineer is designing a multi-Region disaster recovery solution for an Amazon DynamoDB table. The table must be available in a secondary Region with minimal data loss and automatic failover. Which feature should be used?

Accepted Answer

DynamoDB global tables. DynamoDB global tables provide a fully managed, multi-Region, multi-active database solution that replicates data automatically across selected AWS Regions. This ensures automatic failover with eventual consistency and minimal data loss, meeting the disaster recovery requirements for high availability and automatic failover without manual intervention.

Answer

DynamoDB on-demand backup and restore in the secondary Region

Answer

DynamoDB point-in-time recovery (PITR)

Answer

DynamoDB cross-Region snapshot export to S3