DVA-C02 Practice Test 21 — 15 Questions

Question 1

A company runs a containerized web application on Amazon ECS using Fargate. The application needs to store files in Amazon S3. The developer wants to follow the principle of least privilege for the ECS task IAM role. Which IAM policy should be attached to the task role?

Accepted Answer

{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Action":"s3:PutObject","Resource":"arn:aws:s3:::example-bucket/*"}]}. Option B is correct because the policy grants only the necessary S3 actions (PutObject) on the specific bucket. Option A is wrong because it grants all S3 actions. Option C is wrong because it grants s3:* which is too broad. Option D is wrong because it grants read-only access, not write.

Answer

{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Action":"s3:*","Resource":"*"}]}

Answer

{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Action":"s3:*","Resource":"arn:aws:s3:::example-bucket/*"}]}

Answer

{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Action":["s3:GetObject","s3:PutObject"],"Resource":"arn:aws:s3:::example-bucket/*"}]}

Question 2

A developer is building a serverless application that processes images uploaded to an S3 bucket. The bucket triggers a Lambda function that creates a thumbnail and stores it in another S3 bucket. The developer notices that the Lambda function is invoked multiple times for the same object, causing duplicate thumbnails. What is the MOST likely cause?

Accepted Answer

The S3 bucket has multiple event notifications that trigger the same Lambda function.. Option D is correct because if S3 event notifications are misconfigured (e.g., both PutObject and PutObjectAcl events trigger the same function), the function runs multiple times. Option A is wrong because Lambda provides at-least-once execution, but duplicates are not typical unless triggered multiple times. Option B is wrong because S3 does not send duplicate events; the issue is multiple triggers. Option C is wrong because concurrent Lambda executions would not cause duplicates; each invocation processes a unique event.

Answer

S3 event notifications are eventually consistent and may deliver duplicates.

Answer

The Lambda function is configured with a DLQ that causes retries.

Answer

The Lambda function is idempotent and should handle duplicates.

Question 3

A developer wants to debug an AWS Lambda function by viewing real-time logs. Which AWS service should the developer use?

Accepted Answer

Amazon CloudWatch Logs. Option A is correct because CloudWatch Logs captures Lambda logs. Option B is wrong because X-Ray is for tracing. Option C is wrong because CloudTrail is for API calls. Option D is wrong because S3 can store logs but not in real-time.

Answer

AWS X-Ray

Answer

Amazon S3

Answer

AWS CloudTrail

Question 4

A developer is using Amazon DynamoDB as the data store for a web application. The application experiences frequent throttling errors. Which action can reduce throttling without changing the application code?

Accepted Answer

Enable DynamoDB Auto Scaling. Option D is correct because enabling auto scaling adjusts capacity based on traffic. Option A is wrong because indexes don't affect throttling. Option B is wrong because decreasing capacity would worsen throttling. Option C is wrong because increasing read capacity only partially helps.

Answer

Add a secondary index

Answer

Decrease the provisioned write capacity

Answer

Increase the provisioned read capacity only

Question 5

A developer is using AWS Step Functions to orchestrate a workflow that includes a Lambda function for data transformation. The Lambda function occasionally times out after 15 seconds. The Step Function execution fails with a 'States.Timeout' error. The developer wants to retry the Lambda task up to 3 times with exponential backoff. Which configuration should the developer add to the state definition in the Amazon States Language (ASL)?

Accepted Answer

"Retry": [ { "ErrorEquals": ["States.Timeout"], "IntervalSeconds": 1, "BackoffRate": 2, "MaxAttempts": 3 } ]. Option C is correct because it defines a Retry with a 1-second interval, backoff rate of 2, and max attempts of 3. Option A is wrong because it uses 'ErrorEquals' with 'Lambda.ServiceException' which is not the timeout error; the error is 'States.Timeout'. Option B is wrong because it has 'MaxAttempts' as 5, not 3. Option D is wrong because it has only 2 max attempts.

Answer

"Retry": [ { "ErrorEquals": ["States.Timeout"], "IntervalSeconds": 2, "BackoffRate": 3, "MaxAttempts": 5 } ]

Answer

"Retry": [ { "ErrorEquals": ["States.Timeout"], "IntervalSeconds": 1, "BackoffRate": 2, "MaxAttempts": 2 } ]

Answer

"Retry": [ { "ErrorEquals": ["Lambda.ServiceException"], "IntervalSeconds": 1, "BackoffRate": 2, "MaxAttempts": 3 } ]

Question 6

Which THREE actions can a developer take to improve the cold start latency of an AWS Lambda function?

Accepted Answer

Use a language runtime with faster startup time, such as Python or Node.js.. Options A, B, and C are correct. Provisioned concurrency keeps environments warm. Using a smaller runtime (e.g., Python vs Java) reduces startup time. Allocating more memory also increases CPU, speeding up initialization. Option D is wrong because VPC adds latency due to ENI setup. Option E is wrong because increasing timeout does not affect cold start.

Answer

Place the Lambda function inside a VPC.

Answer

Increase the function's timeout setting.

Question 7

A developer needs to send large files (up to 5 GB) from a web application to Amazon S3. The application runs on EC2 instances. Which approach is MOST efficient and reliable?

Accepted Answer

Use S3 multipart upload to upload the file in parts.. Option C is correct because multipart upload is recommended for files over 100 MB and allows parallel uploads with retry capability. Option A is wrong because uploading as a single operation is unreliable for large files. Option B is wrong because EC2 instance store is temporary and not durable. Option D is wrong because S3 Transfer Acceleration speeds up transfers but does not improve reliability for large files; multipart upload is still better.

Answer

Save the file to EC2 instance store and then copy to S3.

Answer

Upload the file as a single S3 PutObject operation.

Answer

Use S3 Transfer Acceleration to upload the file.

Question 8

A company is deploying a microservices architecture on Amazon ECS. Each service needs to store secrets such as database passwords. Which service should be used to securely inject these secrets into containers?

Accepted Answer

AWS Secrets Manager. Option C is correct because AWS Secrets Manager integrates with ECS to inject secrets. Option A is wrong because EFS is a file system. Option B is wrong because SSM Parameter Store can be used but Secrets Manager is preferred for secrets. Option D is wrong because S3 is not secure for secrets.

Answer

Amazon Elastic File System (EFS)

Answer

Amazon S3

Answer

AWS Systems Manager Parameter Store

Question 9

A developer is designing a serverless application that uses AWS Lambda and Amazon DynamoDB. The application needs to handle high traffic spikes without data loss. Which TWO actions should the developer take?

Accepted Answer

Enable DynamoDB Auto Scaling. Option B is correct because SQS decouples processing and provides a buffer. Option D is correct because DynamoDB auto scaling handles capacity. Option A is wrong because Lambda concurrency limit would throttle. Option C is not directly related. Option E is wrong because Provisioned IOPS is for EBS.

Answer

Use Provisioned IOPS for DynamoDB

Answer

Enable DynamoDB Streams

Answer

Increase the Lambda concurrency limit to the maximum

Question 10

A company is building a serverless application using AWS Lambda and Amazon API Gateway. The application needs to process user uploads to an S3 bucket. The Lambda function should be invoked only when new objects are created in the bucket. Which service should be used to trigger the Lambda function?

Accepted Answer

Amazon S3 event notifications. Option B is correct because S3 can send events directly to Lambda when objects are created. Option A is wrong because SQS requires polling. Option C is wrong because CloudWatch Events can't directly trigger from S3 object creation. Option D is wrong because Kinesis requires a stream consumer.

Answer

Amazon Kinesis Data Streams

Answer

Amazon CloudWatch Events

Answer

Amazon Simple Queue Service (SQS)

Question 11

A developer is using AWS CodeBuild to build a Java application. The build fails with 'OutOfMemoryError: Java heap space'. How can the developer fix this without changing the source code?

Accepted Answer

Increase the compute type of the build project. Option A is correct because increasing the compute type provides more memory. Option B is wrong because CodeBuild does not support custom JVM options in buildspec. Option C is wrong because changing the image may not help. Option D is wrong because CodeBuild doesn't have a memory setting separate from compute type.

Answer

Add -Xmx1024m to the buildspec commands

Answer

Change the build image to a smaller one

Answer

Set the memory parameter in the build project

Question 12

A developer is using Amazon API Gateway to expose a Lambda function as a REST API. The Lambda function queries an Amazon RDS database. Under heavy load, the database connection pool is exhausted, causing errors. What is the BEST way to manage database connections in this serverless architecture?

Accepted Answer

Use Amazon RDS Proxy to pool and share database connections.. Option D is correct because RDS Proxy is designed to manage database connection pooling for serverless applications, reducing connection exhaustion. Option A is incorrect because increasing Lambda concurrency would make the problem worse. Option B is incorrect because storing connections in ElastiCache does not help with database connections. Option C is incorrect because using DynamoDB would change the database, not solve the connection management issue.

Answer

Migrate the database to Amazon DynamoDB.

Answer

Increase the concurrency limit of the Lambda function.

Answer

Use Amazon ElastiCache to cache database connections.

Question 13

A company has a Lambda function that processes records from an SQS queue. The function is failing intermittently with timeout errors. The processing time per record varies, but the SQS queue has a visibility timeout of 30 seconds. The Lambda function has a timeout of 1 minute. What is the MOST likely cause of the timeout errors?

Accepted Answer

The SQS visibility timeout is shorter than the Lambda function timeout.. Option B is correct because the Lambda function's maximum execution time is 15 minutes, but the SQS visibility timeout of 30 seconds is shorter than the Lambda timeout of 1 minute. If the Lambda function takes longer than 30 seconds, the message becomes visible again and another Lambda invocation may process it, causing duplicate processing and potential timeouts. Option A is incorrect because Lambda can scale to handle many messages. Option C is irrelevant because batch size affects concurrency but not individual function timeout. Option D is incorrect because 30 seconds is a typical visibility timeout.

Answer

The Lambda function's reserved concurrency is set too low.

Answer

The SQS queue has too many messages causing Lambda to throttle.

Answer

The SQS queue's default visibility timeout of 30 seconds is too long.

Question 14

A company is using AWS CodePipeline to automate its CI/CD pipeline. The pipeline has a source stage that pulls code from an Amazon S3 bucket. Which THREE steps should the developer take to ensure that only approved changes are deployed to production?

Accepted Answer

Use AWS CloudFormation change sets to review changes. Option A is correct because manual approval gates allow review. Option B is correct because S3 versioning enables rollback. Option D is correct because CloudFormation change sets allow preview. Option C is wrong because AWS KMS is not needed. Option E is wrong because cross-account access is not mentioned.

Answer

Configure cross-account access for the pipeline

Answer

Encrypt the S3 bucket with AWS KMS

Question 15

A developer needs to monitor the performance of an Amazon RDS for MySQL database. Which TWO metrics should the developer monitor to detect a potential CPU bottleneck?

Accepted Answer

DatabaseConnections. Option B is correct because CPUUtilization directly shows CPU usage. Option D is correct because DatabaseConnections can indicate high load causing CPU contention. Option A is wrong because FreeStorageSpace is storage. Option C is wrong because ReadLatency is I/O. Option E is wrong because NetworkThroughput is network.

Answer

FreeStorageSpace

Answer

NetworkThroughput

Answer

ReadLatency