DEA-C01 Data Store Management Practice Test 18 — 15 Questions

Question 1

A company is using AWS Glue to run ETL jobs that write data to an Amazon S3 data lake. The jobs are failing with '503 Slow Down' errors. The data engineering team has already implemented retries. What is the BEST long-term solution?

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

Accepted Answer

Implement a backoff strategy to reduce the request rate.. The '503 Slow Down' error from Amazon S3 indicates that the request rate is too high and S3 is throttling the requests. The best long-term solution is to implement a backoff strategy (exponential backoff) to reduce the request rate, which allows the Glue job to automatically slow down and retry with increasing delays, aligning with S3's request rate limits and avoiding sustained throttling.

Answer

Enable S3 Transfer Acceleration.

Answer

Use S3 multipart upload for all objects.

Answer

Increase the number of retries in the Glue job.

Question 2

A company wants to use Amazon Redshift Spectrum to query data in Amazon S3. The data is in Parquet format and partitioned by date. Which step is required to enable Redshift Spectrum?

Accepted Answer

Create an external schema and external table in the AWS Glue Data Catalog.. Redshift Spectrum allows querying data directly in Amazon S3 without loading it into Redshift. To use Spectrum, you must define an external schema and external table in the AWS Glue Data Catalog (or an external Hive metastore) that points to the S3 location and specifies the Parquet format and partition structure. This enables Redshift to read the data in place using the Spectrum engine.

Answer

Load the data into Redshift tables using the COPY command.

Answer

Create a separate Redshift Spectrum cluster.

Answer

Copy the data from S3 to Redshift-managed storage.

Question 3

A company is using Amazon RDS for PostgreSQL with Multi-AZ deployment. The primary instance fails and a failover occurs. After the failover, the application cannot connect to the database. What is the MOST likely cause?

Accepted Answer

The application is using the old primary instance endpoint instead of the RDS CNAME.. After a Multi-AZ failover in Amazon RDS for PostgreSQL, the DNS CNAME record automatically updates to point to the new primary instance in the standby Availability Zone. If the application hardcodes the old primary instance's endpoint (specific IP or DNS name) instead of using the RDS CNAME (which remains constant), it will attempt to connect to the failed instance, causing connectivity loss. The CNAME is the stable connection point that always resolves to the current primary instance.

Answer

The database instance is in a 'stopped' state after failover.

Answer

The Multi-AZ failover requires manual intervention to complete.

Answer

The security group for the RDS instance was not updated during failover.

Question 4

A company is using Amazon ElastiCache for Redis to cache frequently accessed data. The cache hit ratio is low, and the engineering team suspects that the eviction policy is causing important data to be removed. Which eviction policy should be used to minimize eviction of the most frequently accessed keys?

Accepted Answer

allkeys-lfu. The allkeys-lfu (Least Frequently Used) eviction policy is the correct choice because it explicitly tracks and retains keys that are accessed most frequently across the entire keyspace. Since the cache hit ratio is low due to eviction of important data, LFU ensures that frequently accessed keys are evicted last, directly addressing the problem of important data being removed.

Answer

allkeys-lru

Answer

noeviction

Answer

volatile-lru

Question 5

A company is designing a data lake on Amazon S3 for analytics. The data includes sensitive personally identifiable information (PII). Which TWO actions should the company take to protect the data? (Choose TWO.)

Accepted Answer

Enable S3 Block Public Access.. S3 Block Public Access (Option A) prevents any public access to S3 buckets and objects, which is critical for protecting PII from unintended exposure. Default encryption with SSE-KMS (Option E) ensures that all data written to S3 is encrypted at rest using AWS KMS-managed keys, providing both encryption and centralized key management for sensitive data.

Answer

Enable Requester Pays.

Answer

Enable S3 Transfer Acceleration.

Answer

Enable cross-region replication.

Question 6

A company is using Amazon Kinesis Data Streams to ingest real-time clickstream data. The data must be stored in Amazon S3 in near real-time with minimal overhead. Which THREE steps should the data engineer take to achieve this? (Choose THREE.)

Accepted Answer

Configure a Lambda function to transform data before delivery to S3.. A Lambda function can be used as a data transformation step within a Kinesis Data Firehose delivery stream. This allows the clickstream data to be transformed (e.g., parsed, enriched, or reformatted) before being delivered to Amazon S3, enabling near real-time storage with minimal operational overhead.

Answer

Use Kinesis Data Analytics to process and store data in S3.

Answer

Enable S3 cross-region replication for the destination bucket.

Question 7

A company is evaluating Amazon DynamoDB for a new application. The application requires single-digit millisecond latency for read and write operations. Which TWO DynamoDB features should the company enable to achieve this? (Choose TWO.)

Accepted Answer

Use DAX with Write-Through caching.. DAX with Write-Through caching ensures that every write to DynamoDB is also written to the DAX cache, so subsequent reads of the same item are served from the in-memory cache with single-digit millisecond latency. Option D is correct because DynamoDB Accelerator (DAX) is a fully managed, highly available, in-memory cache that reduces read response times from single-digit milliseconds to microseconds, directly meeting the latency requirement for read operations.

Answer

Enable DynamoDB Global Tables.

Answer

Enable DynamoDB Streams.

Answer

Enable auto-scaling for read and write capacity.

Question 8

The exhibit shows the lifecycle configuration for an S3 bucket. Objects in the bucket are 200 days old on average. What will happen to the objects?

Accepted Answer

Objects are in GLACIER now and will be deleted after 365 days from creation.. The lifecycle configuration shows a current version action to transition to GLACIOR (a misspelling of GLACIER) immediately (0 days after creation) and an expiration action to permanently delete the object 365 days after creation. Since the objects are already 200 days old on average, they have already been transitioned to GLACIER storage class. The expiration rule will delete them 365 days from their creation date, not from the current time.

Answer

Objects will be transitioned to GLACIER after 90 days and deleted after 365 days.

Answer

Objects will be transitioned to GLACIER after 200 days and deleted after 365 days.

Answer

Objects will be deleted after 90 days.

Question 9

The exhibit shows the output of describe-table for a DynamoDB table. The application is experiencing throttling errors when reading data. What is the MOST likely cause?

Accepted Answer

The table's provisioned read capacity is too low.. The describe-table output shows the table has provisioned read capacity set to 5, but the application is experiencing throttling errors. Throttling occurs when read requests exceed the provisioned read capacity units (RCUs). Increasing the read capacity or implementing retries with exponential backoff would resolve this. The throttling is directly caused by insufficient provisioned read capacity for the workload.

Answer

The sort key is not used correctly for queries.

Answer

The table has a hot partition due to the HASH key.

Answer

The table size is too large, causing slow reads.

Question 10

A company is using Amazon S3 to store sensitive data. They need to automatically transition objects to S3 Glacier Deep Archive after 90 days and delete them after 7 years. Which S3 lifecycle configuration action should be used?

Accepted Answer

Transition. The S3 lifecycle 'Transition' action is specifically designed to move objects between storage classes. To automatically move objects to S3 Glacier Deep Archive after 90 days, you define a transition rule with a 'Days' value of 90 and a 'StorageClass' of 'DEEP_ARCHIVE'. This action directly meets the requirement for transitioning data to a colder storage tier.

Answer

AbortIncompleteMultipartUpload

Answer

Expiration

Answer

NoncurrentVersionExpiration

Question 11

A data engineer is designing a data store for a time-series application that requires sub-millisecond read latency for the latest data and high ingestion rates. Which AWS service is most suitable?

Accepted Answer

Amazon Timestream. Amazon Timestream is purpose-built for time-series data, offering sub-millisecond read latency for recent data via its in-memory store and supporting high ingestion rates with automatic partitioning and tiering. It is the most suitable choice because it natively handles time-series workloads without requiring manual tuning or schema optimization.

Answer

Amazon DynamoDB

Answer

Amazon ElastiCache for Redis

Answer

Amazon RDS for PostgreSQL

Question 12

A company is migrating an on-premises Hadoop cluster to AWS. The data is stored in HDFS and needs to be accessible by both Amazon EMR and Amazon Redshift Spectrum. Which storage solution is most cost-effective and scalable?

Accepted Answer

Amazon Simple Storage Service (S3). Amazon S3 is the most cost-effective and scalable storage solution for this use case because it provides native integration with both Amazon EMR (via S3A connector or EMRFS) and Amazon Redshift Spectrum (via external tables). Unlike HDFS, S3 decouples compute from storage, allowing you to pay only for the data stored and the compute resources used, with virtually unlimited scalability and 99.999999999% durability.

Answer

Amazon FSx for HDFS

Answer

Amazon Elastic Block Store (EBS)

Answer

Amazon Elastic File System (EFS)

Question 13

A company is using Amazon RDS for MySQL and needs to reduce read latency for a global user base. Which AWS feature should be implemented?

Accepted Answer

Read Replicas. Amazon RDS Read Replicas allow you to offload read traffic from the primary DB instance to one or more read-only copies, which can be placed in different AWS Regions to reduce read latency for a global user base. Unlike Multi-AZ, which is designed for high availability, Read Replicas directly address read performance and latency by distributing read queries closer to users. Cross-Region Replication for RDS MySQL is achieved through Read Replicas, making option C the correct choice for reducing read latency globally.

Answer

Multi-AZ deployment

Answer

Aurora Auto Scaling

Answer

Cross-Region Replication

Question 14

A data engineer is troubleshooting an Amazon Redshift cluster that is experiencing slow query performance. The engineer notices that the disk space is heavily utilized and queries are spilling to disk. What is the most cost-effective solution to improve performance?

Accepted Answer

Resize the cluster to a larger node type or add nodes. When queries spill to disk due to heavy disk utilization, the root cause is insufficient memory or compute capacity relative to the workload. Resizing the cluster (adding nodes or moving to a larger node type) directly increases available memory and CPU, reducing or eliminating disk spill and improving query performance. This is the most cost-effective solution because it scales resources proportionally without requiring manual tuning or schema changes.

Answer

Run VACUUM command to reclaim space

Answer

Change distribution style to KEY

Answer

Apply compression encoding to tables

Question 15

A company needs to store streaming data from IoT devices with a retention period of 7 days for real-time analysis. Which AWS service is most suitable?

Accepted Answer

Amazon Kinesis Data Streams. Amazon Kinesis Data Streams is the most suitable service because it is designed for real-time ingestion and processing of streaming data, such as IoT device telemetry, with a default retention period of 24 hours, extendable up to 365 days. The requirement for a 7-day retention period for real-time analysis aligns perfectly with Kinesis Data Streams' ability to retain data for exactly that duration, allowing consumers to process records in near real-time using the Kinesis Client Library (KCL) or AWS Lambda.

Answer

Amazon DynamoDB

Answer

Amazon Kinesis Data Firehose

Answer

Amazon S3