DEA-C01 Data Operations and Support Practice Test 6 — 15 Questions

Question 1

A data engineer is troubleshooting an AWS Glue job that fails with 'java.lang.OutOfMemoryError: Java heap space'. The job processes a large dataset. Which TWO configuration changes should the engineer consider to resolve this issue? (Choose TWO.)

Accepted Answer

Increase the Spark shuffle partitions configuration (spark.sql.shuffle.partitions).. Options A and B are correct. A: Increasing the number of DPUs provides more memory for the job. B: Increasing the Spark shuffle partitions reduces the amount of data shuffled per partition, reducing memory pressure. Option C is wrong because reducing the number of partitions in the source data may increase partition size. Option D is wrong because using a different data format does not directly address heap space. Option E is wrong because disabling job bookmark may cause reprocessing but not fix memory.

Answer

Change the output format from Parquet to CSV.

Answer

Reduce the number of partitions in the source data.

Answer

Disable job bookmarks to avoid incremental processing.

Question 2

A data engineer is designing a data pipeline that uses AWS Glue to process data from an RDS MySQL database. The pipeline must capture only incremental changes (inserts and updates) and run every hour. Which approach is most cost-effective and reliable?

Accepted Answer

Use Glue job bookmarks to track and process only new and updated records. Option B is correct because Glue job bookmarks track processed data and enable incremental processing without reprocessing full tables. Option A is wrong because CDC from DMS adds complexity and cost. Option C is wrong because full scans are inefficient and costly. Option D is wrong because querying by timestamp may miss updates if timestamps are not indexed or updated.

Answer

Use AWS DMS with change data capture (CDC) to replicate changes to S3

Answer

Add a timestamp column and query rows where timestamp > last run

Answer

Perform a full table scan each hour and compare with previous snapshot

Question 3

A company uses Amazon Kinesis Data Firehose to deliver streaming data to Amazon S3. The delivery stream is failing with 'Insufficient capacity' errors. Which THREE actions should the data engineer take to resolve this issue? (Choose THREE.)

Accepted Answer

Increase the buffer size and buffer interval in the Firehose delivery stream configuration.. Options A, B, and C are correct. A: Increasing buffer size and interval allows Firehose to batch more records, reducing the number of PUT requests. B: Increasing the number of shards in the source Kinesis stream provides more write capacity. C: Requesting a service quota increase for Firehose can raise the default limits. Option D is wrong because S3 bucket versioning does not affect Firehose capacity. Option E is wrong because CloudWatch alarms only alert, they do not resolve capacity issues.

Answer

Enable S3 bucket versioning to handle concurrent writes.

Answer

Configure a CloudWatch alarm to monitor the error rate.

Question 4

A company runs a Redshift cluster and notices that query performance has degraded over time. The data engineer suspects that table statistics are stale. What should the engineer do to improve query performance?

Accepted Answer

Run the ANALYZE command on the tables. Stale table statistics cause the Redshift query optimizer to generate suboptimal execution plans, leading to degraded query performance. Running the ANALYZE command updates these statistics, allowing the optimizer to make better decisions about join order, distribution, and data scan strategies. This directly addresses the root cause of performance degradation over time.

Answer

Rebuild the tables by using CREATE TABLE AS

Answer

Increase the number of slices in the cluster

Answer

Run the VACUUM command on the tables

Question 5

A data pipeline uses AWS Glue to process data from Amazon S3. The job fails with an 'OutOfMemoryError' during the transformation phase. Which action should the data engineer take to resolve this issue?

Accepted Answer

Increase the number of DPUs (Data Processing Units) for the Glue job.. Increasing the number of DPUs allocated to the Glue job provides more memory and processing capacity, which directly addresses the OutOfMemoryError. Option A is wrong because it increases parallelism without addressing memory. Option B is wrong because the error is not related to schema. Option D is wrong because S3 performance is not the issue.

Answer

Enable S3 server-side encryption.

Answer

Increase the number of partitions in the input data.

Answer

Change the data format from CSV to Parquet.

Question 6

A data engineer is monitoring an Amazon EMR cluster and notices that the cluster is running out of disk space on the core nodes. Which action can be taken to resolve this issue?

Accepted Answer

Increase the EBS volume size attached to core nodes. Option A is correct because increasing the volume size of EBS attached to core nodes provides more storage. Option B is wrong because changing instance type affects memory/CPU, not disk. Option C is wrong because Spot Instances are cheaper but do not add disk. Option D is wrong because reducing data retention is not always feasible and may lose data.

Answer

Reduce the retention period of data stored on HDFS

Answer

Change the core node instance type to a compute-optimized type

Answer

Use Spot Instances for core nodes

Question 7

A company runs an Amazon Redshift cluster for analytics. During peak hours, query performance degrades significantly. The data engineer notices that disk space usage is above 80% on many nodes. Which of the following is the MOST effective long-term solution to improve query performance?

Accepted Answer

Resize the cluster to include additional nodes.. Resizing the cluster to add more nodes increases total storage and compute capacity, reducing disk pressure and improving performance. Option A is wrong because vacuuming reclaims space but does not add capacity. Option B is wrong because compression helps but may not be sufficient. Option D is wrong because it only addresses queries waiting for resources.

Answer

Increase the workload management (WLM) queue slots.

Answer

Apply compression encoding to all columns.

Answer

Run the VACUUM command to reclaim space.

Question 8

A company has an S3 data lake with millions of objects. A data engineer needs to provide a daily report of objects that are not accessed for 90 days. The engineer must minimize cost and impact on performance. Which approach should be used?

Accepted Answer

Use S3 Storage Lens to generate a dashboard of object age and last access. Option C is correct because S3 Storage Lens provides cost-effective analytics including last access date. Option A is wrong because S3 Inventory creates daily lists but requires Athena queries and is more complex. Option B is wrong because S3 Server Access Logs can be large and costly to query. Option D is wrong because S3 Select is for querying objects' content, not metadata.

Answer

Enable S3 Inventory and query with Athena

Answer

Use S3 Select on each object to check last access metadata

Answer

Analyze S3 server access logs to find objects not accessed

Question 9

A data engineer needs to monitor Amazon DynamoDB table metrics to detect throttled requests. Which CloudWatch metric should the engineer set an alarm on?

Accepted Answer

ThrottledRequests. Option C is correct because `ThrottledRequests` is the specific Amazon CloudWatch metric that tracks the number of requests to a DynamoDB table that are throttled due to exceeding the provisioned throughput capacity. This metric directly reflects throttling events, making it the appropriate choice for setting an alarm to detect throttled requests.

Answer

ReadThrottleEvents

Answer

SuccessfulRequestLatency

Answer

ConsumedWriteCapacityUnits

Question 10

A data engineer is troubleshooting a failed AWS Glue Crawler. The crawler logs show 'Insufficient permissions to access S3 bucket'. What should the engineer do to resolve this?

Accepted Answer

Update the IAM role used by the crawler to include S3 read permissions. The AWS Glue Crawler uses an IAM role to access data sources. The error 'Insufficient permissions to access S3 bucket' indicates that the IAM role attached to the crawler lacks the necessary S3 read permissions (e.g., s3:GetObject, s3:ListBucket). Updating the IAM role's policy to include these permissions resolves the issue, as the crawler operates under that role, not under a specific IAM user.

Answer

Grant the crawler's IAM user access to the bucket

Answer

Attach a VPC endpoint to the S3 bucket

Answer

Enable S3 default encryption on the bucket

Question 11

A company uses AWS Kinesis Data Streams to ingest real-time data. The data engineer notices that the stream's 'WriteProvisionedThroughputExceeded' error occurs frequently during peaks. Which action should be taken to resolve this issue?

Accepted Answer

Increase the number of shards in the stream.. Increasing the number of shards increases the write capacity, directly addressing the throughput exceeded error. Option B is wrong because the error is not from the producer side. Option C is wrong because the error is about write throughput, not read. Option D is wrong because the error is not about data format.

Answer

Modify the producer to use a different partition key.

Answer

Compress the data before sending to the stream.

Answer

Enable enhanced fan-out for consumers.

Question 12

A company is using Kinesis Data Firehose to deliver data to an S3 bucket. The delivery stream is failing with 'S3 bucket access denied' errors. The bucket policy allows the Firehose service principal. What could be the issue?

Accepted Answer

The IAM role assigned to Firehose lacks s3:PutObject permission. Option C is correct because Firehose uses a trust policy with a service principal but the delivery role must have S3 permissions. Option A is wrong because SSE-KMS requires KMS permissions, not S3 access. Option B is wrong because bucket name is part of the configuration. Option D is wrong because VPC endpoints affect connectivity, not access denied after connection.

Answer

The S3 bucket is in a different VPC

Answer

The S3 bucket uses SSE-KMS and Firehose does not have KMS permissions

Answer

The S3 bucket name contains invalid characters

Question 13

A data engineer is troubleshooting a failed AWS Glue ETL job that reads from a JDBC source. The error log shows 'java.sql.SQLException: Connection timed out'. The job previously ran successfully. Which of the following is the MOST likely cause?

Accepted Answer

The security group for the source database no longer allows traffic from the Glue job's IP range.. The error 'Connection timed out' indicates a network-level failure, not an authentication or schema issue. Since the job previously ran successfully, the most likely cause is that the security group for the source database no longer allows inbound traffic from the Glue job's IP range. AWS Glue ETL jobs run in a VPC with elastic network interfaces, and the security group rules must permit traffic on the JDBC port (e.g., 5432 for PostgreSQL, 3306 for MySQL).

Answer

The JDBC connection string has incorrect credentials.

Answer

The source database schema has changed.

Answer

The Glue job's timeout setting is too low.

Question 14

A data engineer is designing a solution to move data from an on-premises Oracle database to Amazon S3 using AWS DMS. The engineer needs to ensure that data changes are replicated continuously with minimal latency. Which DMS configuration is most appropriate?

Accepted Answer

Use a full-load task with ongoing replication (CDC). Option B is correct because DMS with CDC (change data capture) captures ongoing changes with low latency. Option A is wrong because full load only does initial copy. Option C is wrong because SCT is for schema conversion, not data movement. Option D is wrong because Kinesis is for streaming, but DMS is the right service for database replication.

Answer

Use AWS SCT to convert the schema and then use DMS for full load

Answer

Use a full-load task that runs daily

Answer

Use Kinesis Data Streams to capture changes and write to S3

Question 15

A company stores sensitive data in Amazon S3 and needs to ensure that data is encrypted at rest. Which AWS service can be used to manage the encryption keys?

Accepted Answer

AWS Key Management Service (KMS). AWS KMS is the managed service for creating and controlling encryption keys used to encrypt data. Option A is wrong because IAM manages access, not keys. Option B is wrong because CloudHSM is a hardware security module but is not the only option. Option C is wrong because Secrets Manager is for secrets like passwords.

Answer

AWS Secrets Manager

Answer

AWS Identity and Access Management (IAM)

Answer

AWS Certificate Manager (ACM)