DEA-C01 Practice Test 19 — 15 Questions

Question 1

A data streaming application uses Kinesis Data Streams with 10 shards. The data producer is throttled frequently. Which action should be taken to resolve this issue?

Accepted Answer

Increase the number of shards. Throttling in Kinesis Data Streams occurs when the write throughput exceeds the shard limits. Each shard supports up to 1 MB/s or 1,000 records/s for writes. With 10 shards, the total write capacity is 10 MB/s or 10,000 records/s. Increasing the number of shards (Option D) directly increases the write capacity, resolving the throttling issue by distributing the load across more shards.

Answer

Decrease the data retention period

Answer

Use enhanced fan-out for consumers

Answer

Enable server-side encryption

Question 2

Which TWO actions can help optimize Amazon S3 storage costs for a data lake? (Choose two.)

Accepted Answer

Use S3 Intelligent-Tiering for unpredictable access patterns. S3 Intelligent-Tiering automatically moves objects between two access tiers (frequent and infrequent) when access patterns change, with no retrieval fees and a small monthly monitoring fee. This is ideal for a data lake where access patterns are unpredictable, as it optimizes costs without requiring manual lifecycle rule adjustments.

Answer

Enable S3 Replication to another region

Answer

Use S3 Select to retrieve only needed data

Answer

Enable S3 Transfer Acceleration

Question 3

A company uses AWS Lambda to process events from an S3 bucket. The Lambda function writes transformed data to another S3 bucket. Occasionally, the Lambda invocation fails with 'ResourceNotFoundException'. What is the MOST likely cause?

Accepted Answer

The destination S3 bucket does not exist or the Lambda function's IAM role lacks permissions.. The destination bucket may not exist or the Lambda function's IAM role lacks permissions to write to it. Option A is wrong because Lambda timeouts would cause 'Timeout' error. Option C is wrong because S3 event notifications are reliable. Option D is wrong because the source bucket exists since it triggered the event.

Answer

The Lambda function timed out.

Answer

The S3 event notification is misconfigured.

Answer

The source S3 bucket has versioning disabled.

Question 4

A data engineer needs to ensure that an Amazon Redshift cluster only accepts encrypted connections. Which parameter should be modified?

Accepted Answer

require_SSL. Setting the `require_SSL` parameter to `true` forces all connections to the Amazon Redshift cluster to use SSL/TLS encryption, ensuring that data in transit is encrypted. This parameter is modified in the cluster's parameter group and applies to both JDBC and ODBC connections, as well as the Redshift Query Editor.

Answer

enable_user_activity_logging

Answer

max_concurrency_scaling_clusters

Answer

wlm_json_configuration

Question 5

A company uses AWS Glue ETL jobs to transform data from Amazon RDS to Amazon S3 daily. The job recently started failing with memory errors. The data volume has grown 3x in the past month. Which change should the data engineer make to resolve the issue?

Accepted Answer

Increase the number of DPUs allocated to the Glue job. The Glue job is failing with memory errors due to a 3x increase in data volume. Increasing the number of DPUs (Data Processing Units) allocated to the job provides more memory and compute resources, directly addressing the out-of-memory condition without changing the job logic or architecture.

Answer

Increase the size of the Amazon RDS instance

Answer

Switch the Glue job type from Python Shell to Spark

Answer

Partition the output data in Amazon S3 by date

Question 6

A data engineering team is responsible for an Amazon RDS for PostgreSQL instance that stores financial data. The database is 500 GB in size. The team needs to create a read replica in a different AWS Region for disaster recovery. The source database has automated backups enabled with a retention period of 7 days. The team initiates the cross-region read replica creation. After several hours, the replica status shows 'Replication Lag' of 30 minutes and is increasing. What should the team do to reduce the replication lag?

Accepted Answer

Modify the source DB instance to use a larger instance class.. Modifying the source DB instance to a larger instance class provides more compute and memory resources. If the source instance is resource-constrained, this can reduce I/O contention and allow it to generate and ship write-ahead logs (WAL) more efficiently, potentially decreasing the replication lag to the cross-region read replica. Enabling Multi-AZ on the source database adds a synchronous standby in a different Availability Zone, which does not offload cross-region replication tasks and can increase write latency and resource overhead on the primary, possibly exacerbating replication lag. Deleting and recreating the replica from a snapshot or increasing backup retention does not address ongoing replication performance.

Answer

Delete the replica and create a new one from a snapshot.

Answer

Increase the backup retention period to 35 days.

Answer

Enable Multi-AZ on the source database instance.

Question 7

A startup is building a real-time analytics application using Amazon Kinesis Data Streams and Amazon Kinesis Data Analytics. The application processes clickstream data from a website. The data is also stored in Amazon S3 for historical analysis. The company uses an S3 bucket with a lifecycle policy that transitions objects to Amazon S3 Glacier Deep Archive after 30 days. The data engineering team has configured a Kinesis Data Firehose delivery stream to write data to the S3 bucket. The team notices that the data in S3 is not being transitioned to Glacier Deep Archive after 30 days. The lifecycle policy is correctly configured and has been verified. What is the most likely cause of this issue?

Accepted Answer

The S3 lifecycle rule is configured with a filter that does not match the prefix used by Kinesis Data Firehose.. The most likely cause is that the S3 lifecycle rule has a filter that does not match the prefix used by Kinesis Data Firehose. Firehose writes objects with a specific prefix pattern (e.g., 'year/month/day/hour/...'), and if the lifecycle rule is configured with a different prefix filter, the rule will not apply to those objects. Option A is correct. Option B is incorrect because the minimum 90-day storage period for Glacier Deep Archive is a billing consideration, not a restriction on lifecycle transitions; objects can be transitioned after 30 days, but early deletion fees may apply. Option C is incorrect because S3 Intelligent-Tiering is not required for lifecycle transitions to Glacier Deep Archive; any S3 bucket can have lifecycle rules. Option D is incorrect because S3 Batch Operations are not involved in lifecycle transitions; they are used for bulk operations like copying or restoring objects.

Answer

The Glacier Deep Archive storage class requires a minimum 90-day storage period, so the lifecycle policy cannot transition objects after 30 days.

Answer

The S3 bucket is not enabled for S3 Intelligent-Tiering, which is required for lifecycle transitions to Glacier Deep Archive.

Answer

The S3 bucket does not have S3 Batch Operations enabled to invoke the lifecycle policy.

Question 8

A data pipeline ingests streaming data from Kinesis Data Streams into S3 via Kinesis Data Firehose. Occasionally, small files are written to S3, increasing downstream processing costs. What is the most efficient way to reduce the number of small files?

Accepted Answer

Increase the Firehose buffering interval to 300 seconds and buffering size to 64 MB.. Kinesis Data Firehose allows you to configure buffering hints (size and interval) to control when data is delivered to S3. By increasing the buffering interval to 300 seconds and the buffering size to 64 MB, Firehose accumulates more records before writing, which reduces the number of small files. This is the most efficient approach as it requires no additional infrastructure or post-processing.

Answer

Use a Lambda function to aggregate records before sending to Firehose.

Answer

Use the Kinesis Client Library (KCL) to write larger batches to S3 directly.

Answer

Run a daily AWS Glue job to concatenate small files.

Question 9

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 10

A company is designing a data store for IoT sensor data that is written once and never updated. The data must be stored with high durability and low cost. Which TWO AWS storage services are most suitable? (Choose TWO.)

Accepted Answer

Amazon S3. Amazon S3 is correct because it provides 99.999999999% (11 9's) durability, is designed for write-once-read-many (WORM) workloads, and offers low-cost storage tiers suitable for IoT sensor data that is never updated. S3's object storage model and lifecycle policies allow automatic transition to colder storage, making it ideal for immutable data at scale.

Answer

Amazon ElastiCache

Answer

Amazon EBS

Answer

Amazon DynamoDB

Question 11

A data engineering team needs to transform CSV files to Parquet format after they land in an S3 bucket. The transformation should be triggered automatically as soon as a new file arrives. Which AWS service is best suited for this task?

Accepted Answer

AWS Lambda function triggered by S3 event. AWS Lambda functions can be directly triggered by S3 events (e.g., `s3:ObjectCreated:*`) to process newly uploaded CSV files. This serverless approach provides near-instantaneous, event-driven transformation to Parquet without managing any infrastructure, making it the most cost-effective and simplest solution for this specific use case.

Answer

AWS Batch job submitted by S3 event

Answer

Amazon EMR cluster running continuously

Answer

AWS Glue ETL job scheduled every 5 minutes

Question 12

A company uses Amazon Kinesis Data Analytics for Apache Flink to process streaming data. The application reads from a Kinesis data stream, performs a 1-minute tumbling window aggregation, and writes results to an S3 bucket. Recently, the application started experiencing checkpoint failures and increasing processing delay. Which action should the engineer take FIRST to diagnose the issue?

Accepted Answer

Monitor CPU and memory utilization of the Flink application using Amazon CloudWatch metrics.. Checkpoint failures are often due to insufficient resources (CPU/memory) for the Flink job. Monitoring CPU and memory utilization via CloudWatch metrics directly helps identify resource bottlenecks. Option A (increasing parallelism) is a tuning step that might help but is not diagnostic. Option C (switching to KCL) is not relevant for Flink checkpointing. Option D (increasing checkpoint interval) might reduce checkpoint frequency but does not address the root cause of checkpoint failures. The first step is to check resource utilization.

Answer

Increase the parallelism of the Flink application.

Answer

Switch to the Kinesis Client Library (KCL) for checkpointing.

Answer

Increase the checkpoint interval to reduce checkpoint frequency.

Question 13

A company wants to ingest real-time data from a social media API into Amazon S3 for analysis. The API provides data as JSON records. Which AWS service is best suited for this ingestion?

Accepted Answer

Amazon Kinesis Data Firehose. Amazon Kinesis Data Firehose is the best choice because it is a fully managed service designed to ingest real-time streaming data, such as JSON records from a social media API, and automatically load it into Amazon S3 with optional data transformation and compression. It handles scaling, buffering, and delivery without requiring custom code or infrastructure management, making it ideal for this use case.

Answer

AWS Glue

Answer

Amazon Simple Queue Service (SQS)

Answer

Amazon DataZone

Question 14

Which THREE factors should be considered when selecting a data ingestion service for a high-volume, real-time streaming pipeline that requires exactly-once processing semantics? (Choose 3.)

Accepted Answer

Ability to replay records from a checkpoint. In high-volume streaming pipelines, the ability to replay records from a checkpoint is essential for achieving exactly-once processing semantics. Services like Amazon Kinesis Data Streams and Apache Kafka allow consumers to reset to a specific sequence number or offset, enabling reprocessing of unacknowledged records after a failure without data loss or duplication.

Answer

Support for schema evolution

Answer

Ability to transform data in-flight

Question 15

Refer to the exhibit. A data engineer is creating an IAM policy for an application that sends data to a Kinesis stream and stores processed data in S3. The policy is attached to an IAM role used by an EC2 instance. The application fails to write to S3 with an access denied error. What is the cause?

Accepted Answer

The policy does not allow s3:ListBucket on the bucket.. The error occurs because the IAM policy grants s3:PutObject but not s3:ListBucket on the target S3 bucket. When the application writes to S3, the AWS SDK often performs a ListBucket operation first to verify bucket existence or to handle multipart uploads, and without s3:ListBucket permission, the request is denied with an access denied error.

Answer

The IAM role is not attached to the EC2 instance profile.

Answer

The policy does not allow kinesis:PutRecord on the stream.

Answer

The EC2 instance does not have an internet gateway to reach S3.