DEA-C01 Practice Exam 66 — 20 Questions

Question 1

A data engineer is setting up a data pipeline to ingest streaming data from an IoT fleet. The data must be processed in near real-time and stored in Amazon S3 for analytics. Which THREE AWS services should the engineer consider using?

Accepted Answer

Amazon Kinesis Data Firehose. Option A is correct because Kinesis Data Streams ingests streaming data. Option C is correct because Kinesis Data Firehose can deliver data to S3. Option D is correct because Lambda can process records in near real-time. Option B is incorrect because Glue is batch-oriented. Option E is incorrect because EMR is for big data processing, not streaming ingestion.

Answer

Amazon EMR

Answer

AWS Glue

Question 2

Refer to the exhibit. A company has an S3 bucket 'my-data-lake' with the lifecycle policy shown. Objects under the 'logs/' prefix are being moved to GLACIER after 30 days and expire after 365 days. A data engineer notices that objects older than 365 days are still present in the bucket and are not being deleted. What is the most likely cause?

Accepted Answer

Lifecycle expiration does not apply to objects in GLACIER storage class. Option C is correct because objects in GLACIER storage class can only be expired if they are restored first, or the expiration action must be applied to the current version. The policy does not specify a filter for current version, and GLACIER objects are not deletable by lifecycle without restoration. Option A is wrong because 365 days have passed. Option B is wrong because the prefix is correct. Option D is wrong because the rule is enabled.

Answer

The rule status is disabled

Answer

The prefix filter does not match the objects

Answer

The expiration days count from the transition date, not the object creation date

Question 3

A data engineer creates an IAM policy as shown in the exhibit. The engineer then attaches this policy to an IAM role used by an application that uploads objects to the S3 bucket 'my-bucket'. When the application uploads an object without specifying server-side encryption, what happens?

Accepted Answer

The upload fails with a 403 Access Denied error.. Option D is correct because the policy requires the s3:x-amz-server-side-encryption header to be set to AES256. If the request does not include that header, the condition is not met, and the request is denied with a 403 Access Denied error. Option A is wrong because the object is not uploaded. Option B is wrong because the condition requires AES256, not SSE-C. Option C is wrong because the condition is not met if the header is absent; the request is denied.

Answer

The object is uploaded with SSE-S3 encryption by default.

Answer

The object is uploaded without encryption.

Answer

The object is uploaded with SSE-C encryption.

Question 4

A data engineer is monitoring Amazon CloudWatch metrics for an Amazon Redshift cluster and notices high CPU utilization. The engineer wants to reduce CPU usage. Which TWO actions should the engineer take?

Accepted Answer

Enable concurrency scaling to offload read queries to additional clusters.. Options B and C are correct. Setting concurrency scaling offloads queries, and using sort keys reduces the amount of data scanned. Option A is wrong because vacuum does not reduce CPU significantly. Option D is wrong because increasing node count increases CPU capacity but not reduce usage. Option E is wrong because enabling audit logging adds CPU overhead.

Answer

Increase the number of nodes in the cluster.

Answer

Run the VACUUM command on all tables.

Answer

Enable audit logging to monitor queries.

Question 5

A data engineer is using Amazon EMR to process large datasets. The cluster uses a mix of Spot Instances and On-Demand Instances. The engineer wants to reduce costs while ensuring the job can complete even if Spot Instances are reclaimed. Which TWO actions should the engineer take? (Choose two.)

Accepted Answer

Enable Instance Fleets to use multiple instance types for Spot Instances.. Option A is correct because enabling Instance Fleets allows EMR to diversify instance types for Spot, reducing the chance of interruption. Option D is correct because using a task instance group with Spot instances for non-critical tasks ensures that only those tasks are interrupted. Option B is incorrect because using only On-Demand increases cost. Option C is incorrect because reducing core nodes may cause data loss if Spot nodes storing HDFS are reclaimed. Option E is incorrect because enabling termination protection is for accidental termination, not Spot interruptions.

Answer

Use only On-Demand Instances for all nodes.

Answer

Use Spot Instances for core nodes to reduce cost.

Answer

Enable termination protection for the cluster.

Question 6

A data engineer is designing a disaster recovery strategy for an Amazon RDS for MySQL database with Multi-AZ deployment. Which THREE actions should the engineer take to meet a Recovery Point Objective (RPO) of 5 minutes and a Recovery Time Objective (RTO) of 15 minutes? (Choose THREE.)

Accepted Answer

Enable automated backups with a retention period of 7 days.. Options A, B, and D provide fast failover and minimal data loss. Option A ensures automatic failover to a standby in another AZ. Option B (cross-region read replica) can be promoted in minutes. Option D (automated backups) provide point-in-time recovery. Option C (snapshots to S3) is slower and may not meet RTO. Option E (Single-AZ) increases risk.

Answer

Configure the DB instance to be Single-AZ for simplicity.

Answer

Export automated snapshots to an S3 bucket in a different region.

Question 7

A data pipeline uses AWS Glue to process data from Amazon S3 and write results to Amazon Redshift. The pipeline fails intermittently with the error 'S3ServiceException: Access Denied'. The IAM role used by Glue has permissions to read from the S3 bucket. What is the most likely cause of this error?

Accepted Answer

The S3 bucket policy denies access to the Glue job's IAM role. Option C is correct because S3 bucket policies can explicitly deny access even if the IAM role allows it. Option A is wrong because S3 Transfer Acceleration is not related to access denied errors. Option B is wrong because S3 is not region-specific for the error. Option D is wrong because S3 Server Access Logging does not affect access permissions.

Answer

The S3 bucket is in a different AWS Region than the Glue job

Answer

S3 Server Access Logging is enabled and blocking requests

Answer

The S3 bucket has S3 Transfer Acceleration enabled

Question 8

Refer to the exhibit. A data engineer runs two queries on an Athena table partitioned by 'ds'. Both queries scan the same amount of data. What does this indicate?

Accepted Answer

The partition column is not being used as a filter. Option D is correct because if the partition filter is not pushed down, Athena scans all partitions. Option A is wrong because the data is partitioned. Option B is wrong because partition pruning should reduce data scanned. Option C is wrong because the table is partitioned.

Answer

The table does not have any partitions defined

Answer

The table is not partitioned

Answer

Partition pruning is working correctly

Question 9

A data engineer runs an AWS Glue ETL job that transforms data in Amazon S3. The job fails with the error shown in the exhibit. Which action will MOST likely fix the issue?

Accepted Answer

Change the worker type from G.1X to G.2X.. Option B is correct because the error indicates an out-of-memory error in the Spark executor. Increasing the worker type (e.g., from G.1X to G.2X) provides more memory per worker. Option A is wrong because increasing the number of workers does not increase memory per worker if the worker type is unchanged. Option C is wrong because decreasing the number of workers reduces parallelism and does not help memory. Option D is wrong because the error is not related to IAM permissions.

Answer

Decrease the number of workers from 2 to 1.

Answer

Add an IAM policy that grants the Glue job permission to write to S3.

Answer

Increase the number of workers from 2 to 4.

Question 10

A data engineer is monitoring an Amazon Kinesis Data Stream and notices that the 'WriteProvisionedThroughputExceeded' metric is frequently elevated. The stream has 5 shards and is used by multiple producers. What is the BEST action to resolve this issue?

Accepted Answer

Increase the number of shards in the Kinesis data stream.. Option B is correct because WriteProvisionedThroughputExceeded indicates that the write rate exceeds the shards' capacity. Increasing the number of shards increases the total write capacity. Option A is incorrect because retries do not resolve the root cause of insufficient capacity. Option C is incorrect because reducing the retention period does not affect write throughput. Option D is incorrect because enhancing the consumer's processing speed does not affect write throttling.

Answer

Increase the consumer's processing speed to reduce lag.

Answer

Reduce the data retention period of the stream.

Answer

Implement exponential backoff and retries in the producer applications.

Question 11

A data engineer is troubleshooting a failed AWS Glue job that reads from an Apache Hive metastore in an Amazon EMR cluster. The error message indicates 'ClassNotFoundException: org.apache.hadoop.hive.ql.metadata.HiveException'. The Glue job uses a custom Python shell script. What is the most likely cause of this error?

Accepted Answer

Include the Hive JAR files in the 'Python library path' or use a Glue version with Hive support.. Option C is correct because the ClassNotFoundException for Hive classes indicates that the required Hive JARs are not available in the Glue job's classpath. The Glue job needs to include Hive jars either via a library path or by using a Glue version that supports Hive connectivity. Option A is incorrect because the Python script itself does not need to be modified to include imports; the JARs must be provided. Option B is incorrect because network connectivity would not cause a class not found error. Option D is incorrect because the error is not about IAM permissions.

Answer

Check the network connectivity between Glue and the EMR cluster.

Answer

Modify the Python script to import the Hive libraries manually.

Answer

Update the IAM role to allow 'hive:Describe*' actions.

Question 12

A data engineer is troubleshooting a failed AWS Glue job that reads from an Amazon RDS for MySQL table. The error message indicates 'java.sql.SQLException: No suitable driver'. What is the most likely cause?

Accepted Answer

The MySQL JDBC driver JAR is not included in the Glue job's dependencies.. Option A is correct because the MySQL JDBC driver must be included in the Glue job's dependent JARs or as a Python module. Option B is incorrect because the driver class name is correct; the driver JAR is missing. Option C is incorrect because the error is about driver, not connection. Option D is incorrect because subnet routing does not affect driver loading.

Answer

The Glue job is using the wrong JDBC driver class name.

Answer

The Glue job's VPC subnet does not have a route to the RDS instance.

Answer

The RDS instance is not publicly accessible.

Question 13

A company uses AWS DMS to migrate an on-premises Oracle database to Amazon Aurora PostgreSQL. The migration is ongoing with continuous replication. The data engineer notices that the target Aurora database has a higher lag than expected. Which action would most likely reduce the lag?

Accepted Answer

Increase the number of parallel tasks in the DMS task settings. Option D is correct because increasing the number of parallel tasks improves throughput. Option A is wrong because turning off validation reduces reliability but may help slightly. Option B is wrong because it does not affect replication lag. Option C is wrong because batch-optimized apply is not for Aurora.

Answer

Increase the size of the S3 bucket used for staging

Answer

Enable Batch Optimized Apply on the DMS task

Answer

Disable validation of data on the target

Question 14

A company's Amazon Redshift cluster is running slowly. The data engineer suspects that table design is the cause. Which TWO design practices can improve query performance? (Choose TWO.)

Accepted Answer

Define appropriate sort keys on frequently filtered columns.. Options A and B are correct. Sort keys help the query optimizer prune blocks, and distribution keys reduce data movement. Option C is wrong because VARCHAR is variable-length and may not improve performance. Option D is wrong because GROUP BY is not a design practice. Option E is wrong because adding more slices (via cluster resize) is not a table design change.

Answer

Use GROUP BY instead of DISTINCT in queries.

Answer

Increase the number of slices per node by resizing the cluster.

Answer

Use VARCHAR instead of CHAR for fixed-length strings.

Question 15

Which TWO are valid approaches to troubleshoot a slow Amazon Redshift query? (Choose two.)

Accepted Answer

Check for table locks using STV_LOCKS.. Options B and D are correct. Using EXPLAIN to review the query plan and checking for table locks are troubleshooting steps. Option A is wrong because VACUUM reclaims space, not directly troubleshoots slow queries. Option C is wrong because DISTSTYLE is a design choice, not a troubleshooting step. Option E is wrong because enabling encryption does not affect query performance.

Answer

Enable encryption on the cluster.

Answer

Run VACUUM on the table.

Answer

Alter the table to change DISTSTYLE to KEY.

Question 16

A company runs a daily batch processing job on Amazon EMR that reads data from Amazon S3 and writes results back to S3. The job takes longer than expected. The engineer wants to monitor the job's resource utilization. Which AWS service should be used to collect and visualize metrics such as CPU and memory usage of the EMR cluster's nodes?

Accepted Answer

Amazon CloudWatch with the CloudWatch Agent installed on the EMR nodes.. Option A is correct because CloudWatch can collect custom metrics from EMR via the CloudWatch agent or EMR metrics integration. Option B is incorrect because CloudTrail records API calls, not resource utilization. Option C is incorrect because AWS Config tracks configuration changes. Option D is incorrect because Athena is a query service, not a monitoring service.

Answer

AWS Config to record configuration changes in the EMR cluster.

Answer

Amazon Athena to query EMR job logs stored in S3.

Answer

AWS CloudTrail to log API calls made by the EMR job.

Question 17

A data engineer is troubleshooting an AWS Glue job that writes data to an Amazon S3 bucket in Parquet format. The job runs successfully but the output files are smaller than the configured 'groupFiles' size. The engineer has set 'groupFiles' to 'inPartition' and 'groupSize' to 1 GB. The input data is 10 GB in a single partition. What is the most likely reason for the small files?

Accepted Answer

The 'groupFiles' parameter only affects the input read phase, not the output write phase.. Option B is correct because 'groupFiles' only works when the input data is already small and needs to be coalesced. However, if the input is large and the job writes output, the output file size is determined by the number of Spark partitions, not grouping. The grouping feature only applies to reading input files. Option A is wrong because the setting is correct. Option C is wrong because grouping is a read-time feature, not write-time. Option D is wrong because grouping does not require repartitioning.

Answer

The 'groupFiles' parameter is deprecated in the current Glue version.

Answer

The 'groupFiles' parameter is misspelled or set incorrectly.

Answer

The engineer must also set 'repartition' to 1 to merge output files.

Question 18

A data engineer notices that an AWS Glue ETL job that processes streaming data from Amazon Kinesis Data Streams is failing intermittently with a 'ResourceNotFoundException' error for the Kinesis stream. The job has been running successfully for weeks. Which action should the engineer take to resolve the issue?

Accepted Answer

Add the 'kinesis:DescribeStream' permission to the IAM role used by the Glue job.. Option C is correct because the most common cause of intermittent 'ResourceNotFoundException' for a Kinesis stream is that the IAM role used by the Glue job does not have the kinesis:DescribeStream permission, which is required for the job to check stream details. Option A is incorrect because increasing the Kinesis shard count would not resolve a permissions issue. Option B is incorrect because the Kinesis stream name must match exactly; case sensitivity would cause a consistent error, not intermittent. Option D is incorrect because the timeout setting on the Glue job would not cause a resource not found error.

Answer

Increase the number of shards in the Kinesis data stream to handle higher throughput.

Answer

Rename the Kinesis data stream to match the stream name used in the Glue job exactly, including case.

Answer

Increase the timeout for the Glue job in the job configuration.

Question 19

A company uses Amazon S3 to store sensitive data. The security team requires that all data in transit between on-premises applications and S3 be encrypted. The data engineer must implement a solution that meets this requirement without changing the applications. Which TWO solutions should the engineer consider? (Choose two.)

Accepted Answer

Use an S3 VPC Endpoint and enforce the use of HTTPS through bucket policies.. Option A is correct because using an S3 VPC Endpoint with a gateway endpoint ensures traffic stays within AWS and can enforce encryption via policies. Option C is correct because mounting S3 as a file system using AWS Storage Gateway with HTTPS ensures encryption in transit. Option B is incorrect because default encryption is for data at rest, not in transit. Option D is incorrect because S3 Transfer Acceleration does not enforce encryption; it uses HTTPS but is optional. Option E is incorrect because SSE-S3 is for data at rest.

Answer

Enable S3 Transfer Acceleration on the bucket.

Answer

Enable default encryption on the S3 bucket.

Answer

Use server-side encryption with S3 managed keys (SSE-S3).

Question 20

Refer to the exhibit. A data engineer sees this error log from an Amazon EC2 instance that is trying to access an S3 bucket in the us-west-2 region. The EC2 instance is in a VPC with a private subnet and no internet gateway. What is the MOST likely cause of this error?

Accepted Answer

The VPC does not have a VPC endpoint for S3.. Option D is correct. The EC2 instance is in a private subnet without internet gateway, so it cannot reach S3 over the internet. A VPC endpoint (Gateway or Interface) is needed for private connectivity. Option A is incorrect because the bucket exists (DNS resolves). Option B is incorrect because the error is a connection timeout, not a 403. Option C is incorrect because there is no indication of an incorrect region.

Answer

The S3 bucket is in a different region than us-west-2.

Answer

The S3 bucket does not exist.

Answer

The IAM role attached to the EC2 instance does not have s3:GetObject permission.