DEA-C01 Practice Exam 53 — 20 Questions

Question 1

A data engineer needs to transform JSON data from an S3 bucket into Parquet format for efficient querying with Amazon Athena. The transformation must be serverless and event-driven. Which approach meets these requirements?

Accepted Answer

Use S3 event notifications to invoke a Lambda function that runs PySpark to convert the data.. S3 event notifications trigger a Lambda function that uses PySpark to convert JSON to Parquet. Athena is query-only, Glue requires a job trigger, and EMR is not serverless.

Answer

Use AWS Glue with a scheduled crawler to convert the data.

Answer

Use Amazon Athena to convert JSON to Parquet on the fly.

Answer

Use Amazon EMR with a long-running cluster to process S3 data.

Question 2

A data engineer attached this IAM policy to a Lambda function used to transform data in S3. The function is unable to write output to the bucket. What is the most likely reason?

Accepted Answer

The policy does not allow the s3:ListBucket action on the bucket.. The policy allows GetObject and PutObject on objects, but not the s3:ListBucket action required to check existence or list objects. The function likely needs ListBucket to write or verify.

Answer

The resource ARN is missing the bucket-level ARN.

Answer

The policy does not allow the s3:DeleteObject action.

Answer

The policy does not allow the s3:PutObjectAcl action.

Question 3

A company wants to ingest data from SaaS applications (e.g., Salesforce, Marketo) into Amazon S3 for analytics. The data volume is moderate and updates occur frequently. Which AWS service is BEST suited for this task?

Accepted Answer

Amazon AppFlow. Option A is correct. AppFlow is designed to transfer data from SaaS applications to AWS services like S3. Option B is wrong because Glue is for ETL, not direct SaaS ingestion. Option C is wrong because Kinesis is for streaming, not batch from SaaS. Option D is wrong because DMS is for database migrations.

Answer

Amazon Kinesis Data Streams

Answer

AWS Database Migration Service (DMS)

Answer

AWS Glue

Question 4

A data engineer is designing a streaming ingestion pipeline using Amazon Kinesis Data Streams. The stream has 10 shards, and the data volume is expected to grow by 50% over the next month. The engineer needs to ensure that the pipeline can scale without manual intervention. Which approach should be used?

Accepted Answer

Switch the Kinesis stream to on-demand capacity mode. Option B is correct because Kinesis Data Streams supports automatic scaling using the 'On-demand' capacity mode, which adjusts shards based on traffic. Option A is wrong because Auto Scaling groups are for EC2, not Kinesis. Option C is wrong because CloudWatch Alarms can trigger auto scaling, but scaling a Kinesis stream via API requires custom code; on-demand mode is simpler. Option D is wrong because Lambda does not natively scale the stream.

Answer

Set up a CloudWatch Alarm to trigger a Lambda function to add shards

Answer

Use an Auto Scaling group to add more shards

Answer

Configure the stream to use a Lambda function that scales shards

Question 5

A company streams clickstream data from websites to Amazon Kinesis Data Streams. A Lambda function processes each record and writes it to Amazon S3. Recently, the function has been timing out under high load. Which solution should a data engineer implement to handle the increased throughput?

Accepted Answer

Increase the number of shards in the Kinesis data stream.. Option C is correct because increasing the number of shards in Kinesis Data Streams increases parallelism, allowing more Lambda invocations to process records concurrently. Option A is wrong because writing to S3 more frequently does not reduce Lambda processing time. Option B is wrong because Lambda already processes records; increasing memory may help but does not address the root cause of limited shard count. Option D is wrong because S3 does not support streaming directly.

Answer

Increase the Lambda function's timeout value.

Answer

Increase the memory allocated to the Lambda function.

Answer

Configure Amazon S3 Event Notifications to trigger Lambda directly.

Question 6

A company uses AWS Glue to transform data in S3. The Glue job fails with memory errors. Which THREE actions can help resolve this?

Accepted Answer

Optimize the transformation to use pushdown predicates.. Options A, B, and E are correct. Increasing DPUs (A) adds more worker nodes. Using a larger worker type (B) increases memory per worker. Optimizing transformations like using pushdown predicates (E) reduces data scanned. Option C is wrong because reducing DPUs would make the problem worse. Option D is wrong because increasing timeout does not address memory issues.

Answer

Increase the job timeout.

Answer

Decrease the number of DPUs.

Question 7

A company needs to ingest data from an on-premises Oracle database into Amazon S3 for analytics. The data volume is about 1 TB initially, with daily incremental updates of about 10 GB. Which TWO services can be combined to achieve this with minimal custom code?

Accepted Answer

Amazon S3. Options A and D are correct because AWS DMS can perform full load and ongoing replication, and S3 is the target. Option B (Kinesis Data Streams) is for real-time streaming, not database migration. Option C (Glue) can be used but often requires more custom code than DMS. Option E (Athena) is a query service, not data movement.

Answer

AWS Glue

Answer

Amazon Kinesis Data Streams

Answer

Amazon Athena

Question 8

Refer to the exhibit. A data engineer is troubleshooting a Glue job that reads objects from this S3 bucket. The job runs successfully but produces no output. The Glue catalog table points to the same S3 path. What is the most likely cause?

Accepted Answer

The S3 key does not follow Hive-style partitioning (e.g., year=2024/month=01).. Option C is correct because Glue expects a partition structure (e.g., year=2024/month=01/day=01) to automatically discover partitions. The current key has no partition markers. Option A is wrong because Glue can read application/octet-stream. Option B is wrong because storage class is STANDARD. Option D is wrong because metadata is irrelevant to Glue catalog.

Answer

The object metadata is too large.

Answer

The StorageClass is not supported by Glue.

Answer

The ContentType is not supported by Glue.

Question 9

A company needs to transfer 20 TB of historical data from an on-premises Hadoop cluster to Amazon S3. The network bandwidth is limited and the transfer must complete within one week. Which service should the company use?

Accepted Answer

AWS Snowball Edge. Option C is correct because AWS Snowball is designed for large-scale data transfers with limited bandwidth. Option A is wrong because DataSync over the internet may not meet the deadline. Option B is wrong because the bandwidth is insufficient. Option D is wrong because S3 Transfer Acceleration speeds up uploads but still uses the internet.

Answer

Amazon S3 Transfer Acceleration

Answer

AWS Direct Connect with DataSync

Answer

AWS DataSync over a VPN connection

Question 10

A company is ingesting streaming data into Kinesis Data Streams. The consumer application experiences high latency due to a single shard bottleneck. What is the most effective way to reduce latency?

Accepted Answer

Increase the number of shards in the data stream.. Increasing the number of shards increases throughput and reduces latency. Waiting for autoscaling is passive, using KCL is for processing, and switching to Firehose changes the architecture.

Answer

Wait for automatic scaling to add shards.

Answer

Use the Kinesis Client Library (KCL) to process records.

Answer

Switch to Amazon Kinesis Data Firehose.

Question 11

A data engineer runs the command shown. The consumer application is unable to read data older than 24 hours. What is the most likely cause?

Accepted Answer

The retention period is set to 24 hours, so data older than 24 hours is deleted.. The stream's retention period is 24 hours, meaning data is automatically deleted after 24 hours. The consumer tries to read data older than 24 hours, which is no longer available.

Answer

The shard has reached its maximum sequence number.

Answer

The stream is encrypted with KMS, preventing access.

Answer

The stream is in ACTIVE status but not processing data.

Question 12

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.. Option B is correct. 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 13

A company needs to ingest data from multiple SaaS applications (e.g., Salesforce, Marketo) into Amazon S3 for analytics. The data sources have different schemas and update frequencies. Which AWS service should be used to build this ingestion pipeline with minimal code?

Accepted Answer

Amazon AppFlow. Option C is correct because AWS Glue has built-in connectors for many SaaS applications and can schedule crawlers to discover schema and extract data. Option A is wrong because Kinesis Data Firehose is for streaming data, not for batch extraction from SaaS APIs. Option B is wrong because AppFlow is specifically designed for SaaS data ingestion with minimal code. Actually, AppFlow is the correct answer; AWS Glue also has connectors but requires more setup. Correcting: Amazon AppFlow is purpose-built for ingesting data from SaaS applications to S3. Option C is wrong because Glue has connectors but AppFlow is simpler. The correct answer is B.

Answer

AWS Data Pipeline

Answer

AWS Glue

Answer

Amazon Kinesis Data Firehose

Question 14

A data engineer needs to ingest JSON files from an on-premises SFTP server into Amazon S3. The files are uploaded daily and each file is up to 500 MB. The solution must be serverless and minimize cost. Which service should the engineer use?

Accepted Answer

AWS Transfer Family (SFTP) endpoint.. Option B is correct because AWS Transfer Family supports SFTP and can automatically transfer files to S3, with no need to manage servers. Option A is wrong because AWS DataSync requires an agent on-premises. Option C is wrong because S3 Transfer Acceleration is for speeding up transfers to S3, not for ingesting from SFTP. Option D is wrong because Kinesis Data Firehose is for streaming data, not file-based SFTP transfers.

Answer

Amazon Kinesis Data Firehose.

Answer

AWS DataSync with an on-premises agent.

Answer

Amazon S3 Transfer Acceleration.

Question 15

A data engineer is implementing a CDC (Change Data Capture) pipeline from a relational database to Amazon S3 using AWS Database Migration Service (DMS). Which TWO configurations are required for continuous replication?

Accepted Answer

Enable binary logging on the source database.. Options A and C are correct. To enable ongoing replication, DMS needs to have full load completed (A) and the source database must have continuous change capture enabled (e.g., binary logs for MySQL) (C). Option B is wrong because the target table must exist before replication. Option D is wrong because DMS does not need a VPC endpoint; it connects via the internet or VPN. Option E is wrong because transformation rules are optional.

Answer

Define transformation rules in the DMS task.

Answer

Configure a VPC endpoint for DMS.

Answer

Pre-create the target table in S3.

Question 16

A company uses AWS Glue to catalog data in Amazon S3. The data arrives in Parquet format, but the crawler fails to update the schema when new columns are added. What is the most likely cause?

Accepted Answer

The crawler configuration has 'Update the table definition' set to 'Ignore the change'.. Option C is correct because the crawler's catalog update policy may be set to 'Update the table definition' but not 'Add new columns only', or it might be set to 'Ignore the change'. Option A is wrong because Parquet schema evolves naturally. Option B is wrong because S3 bucket versioning does not affect crawler schema updates. Option D is wrong because the Glue Data Catalog is the target, not the source.

Answer

The Glue Data Catalog is not configured to accept schema changes.

Answer

Parquet files do not support schema evolution.

Answer

The S3 bucket has versioning disabled.

Question 17

A company needs to ingest streaming data from an existing Amazon Kinesis Data Streams into Amazon S3 with partitioning by date. Which TWO services can accomplish this with minimal coding? (Choose two.)

Accepted Answer

Amazon Kinesis Data Firehose

Answer

AWS Glue Streaming

Answer

Amazon Kinesis Data Analytics

Answer

Amazon S3 Transfer Acceleration

Question 18

A company is using Amazon Kinesis Data Streams with a Lambda consumer to process real-time events. The Lambda function is triggered by a DynamoDB stream to update a counter. Recently, the counter has been inaccurate due to duplicate processing. What is the most likely cause?

Accepted Answer

The Lambda function is not idempotent and is being retried on failures. Option D is correct because Lambda functions may be invoked multiple times for the same record if they fail or time out, leading to duplicates if the operation is not idempotent. Option A is wrong because DynamoDB streams guarantee at-least-once delivery, not exactly-once. Option B is wrong because Kinesis shard rebalancing does not cause duplicates. Option C is wrong because Lambda concurrency limits would cause throttling, not duplicates.

Answer

The DynamoDB stream is configured with 'TRIM_HORIZON' iterator type

Answer

The Lambda function's reserved concurrency is too low

Answer

The Kinesis stream has undergone a shard rebalance

Question 19

An organization uses AWS Lake Formation to manage a data lake in S3. A new data engineer needs to create a Glue ETL job that reads from a Lake Formation-managed table. The engineer has been granted SELECT permission on the table via Lake Formation. However, the job fails with an AccessDenied error. What is the MOST likely cause?

Accepted Answer

The IAM role used by the Glue job does not have Lake Formation permissions.. Option C is correct because Glue jobs need an IAM role that has Lake Formation permissions to access the table; the error indicates the job's IAM role lacks necessary permissions. Option A is wrong because S3 permissions are managed by Lake Formation, but access is granted via Lake Formation, not direct S3 bucket policies. Option B is wrong because the table already exists; there is no need to register. Option D is wrong because Lake Formation does not require a VPC endpoint.

Answer

The S3 bucket policy does not allow the Glue job to access the data.

Answer

The table has not been registered with Lake Formation.

Answer

The Glue job is not running in the same VPC as Lake Formation.

Question 20

A data engineering team needs to ingest CSV files from an S3 bucket into a Redshift cluster on a daily basis. The files are large (up to 100 GB each). Which approach is MOST cost-effective and efficient?

Accepted Answer

Use the Redshift COPY command with an IAM role to load data directly from S3.. Using the COPY command with IAM role is the recommended way to load large data into Redshift efficiently. Option B (AWS Data Pipeline) adds cost and complexity; Option C (Kinesis Firehose) is for streaming; Option D (Lambda) has time and memory limits.

Answer

Use Amazon Kinesis Data Firehose to load data into Redshift.

Answer

Use AWS Data Pipeline to copy data from S3 to Redshift.

Answer

Use a Lambda function to read each file and insert rows individually.