DVA-C02 Free Practice Test

A company developed an API application on AWS by using Amazon CloudFront, Amazon API Gateway, and AWS Lambda. The API has a minimum of four requests every second. A developer notices that many API users run the same query by using the POST method. The developer wants to cache the POST request to optimize the API resources. Which solution will meet these requirements?

1. A. Configure the CloudFront cach
2. B. Update the application to return cached content based upon the default request headers.
3. C. Override the cache method in the selected stage of API Gatewa
4. D. Select the POST method.
5. E. Save the latest request response in Lambda /tmp director
6. F. Update the Lambda function to check the /tmp directory.
7. G. Save the latest request in AWS Systems Manager Parameter Stor
8. H. Modify the Lambda function to take the latest request response from Parameter Store.

Correct Answer: B
Amazon API Gateway provides tools for creating and documenting web APIs that route HTTP requests to Lambda functions2. You can secure access to your API with authentication and authorization controls. Your APIs can serve traffic over the internet or can be accessible only within your VPC2. You can override the cache method in the selected stage of API Gateway2. Therefore, option B is correct.

A mobile app stores blog posts in an Amazon DynacnoDB table Millions of posts are added every day and each post represents a single item in the table. The mobile app requires only recent posts. Any post that is older than 48 hours can be removed.
What is the MOST cost-effective way to delete posts that are older man 48 hours?

1. A. For each item add a new attribute of type String that has a timestamp that is set to the blog post creation tim
2. B. Create a script to find old posts with a table scan and remove posts that are order than 48 hours by using the Balch Write ltem API operatio
3. C. Schedule a cron job on an Amazon EC2 instance once an hour to start the script.
4. D. For each item add a new attribute of typ
5. E. String that has a timestamp that its set to the blog post creation tim
6. F. Create a script to find old posts with a table scan and remove posts that are Oder than 48 hours by using the Batch Write item API operatin
7. G. Place the script in a container imag
8. H. Schedule an Amazon Elastic Container Service (Amazon ECS) task on AWS Far gate that invokes the container every 5 minutes.
9. I. For each item, add a new attribute of type Date that has a timestamp that is set to 48 hours after the blog post creation tim
10. J. Create a global secondary index (GSI) that uses the new attribute as a sort ke
11. K. Create an AWS Lambda function that references the GSI and removes expired items by using the Batch Write item API operation Schedule me function with an Amazon CloudWatch event every minute.
12. L. For each item add a new attribute of typ
13. M. Number that has timestamp that is set to 48 hours after the blog pos
14. N. creation time Configure the DynamoDB table with a TTL that references the new attribute.

Correct Answer: D
This solution will meet the requirements by using the Time to Live (TTL) feature of DynamoDB, which enables automatically deleting items from a table after a certain time period. The developer can add a new attribute of type Number that has a timestamp that is set to 48 hours after the blog post creation time, which represents the expiration time of the item. The developer can configure the DynamoDB table with a TTL that references the new attribute, which instructs DynamoDB to delete the item when the current time is greater than or equal to the expiration time. This solution is also cost- effective as it does not incur any additional charges for deleting expired items. Option A isnot optimal because it will create a script to find and remove old posts with a table scan and a batch write item API operation, which may consume more read and write capacity units and incur more costs. Option B is not optimal because it will use Amazon Elastic Container Service (Amazon ECS) and AWS Fargate to run the script, which may introduce additional costs and complexity for managing and scaling containers. Option C is not optimal because it will create a global secondary index (GSI) that uses the expiration time as a sort key, which may consume more storage space and incur more costs.
References: Time To Live, Managing DynamoDB Time To Live (TTL)

A developer is using AWS Step Functions to automate a workflow The workflow defines each step as an AWS Lambda function task The developer notices that runs of the Step Functions state machine fail in the GetResource task with either an UlegalArgumentException error or a TooManyRequestsException error
The developer wants the state machine to stop running when the state machine encounters an UlegalArgumentException error. The state machine needs to retry the GetResource task one additional time after 10 seconds if the state machine encounters a TooManyRequestsException error. If the second attempt fails, the developer wants the state machine to stop running.
How can the developer implement the Lambda retry functionality without adding unnecessary complexity to the state machine'?

1. A. Add a Delay task after the GetResource tas
2. B. Add a catcher to the GetResource tas
3. C. Configure the catcher with an error type of TooManyRequestsExceptio
4. D. Configure the next step to be the Delay task Configure the Delay task to wait for an interval of 10 seconds Configure the next step to be the GetResource task.
5. E. Add a catcher to the GetResource task Configure the catcher with an error type of TooManyRequestsExceptio
6. F. an interval of 10 seconds, and a maximum attempts value of 1. Configure the next step to be the GetResource task.
7. G. Add a retrier to the GetResource task Configure the retrier with an error type of TooManyRequestsException, an interval of 10 seconds, and a maximum attempts value of 1.
8. H. Duplicate the GetResource task Rename the new GetResource task to TryAgain Add a catcher to the original GetResource task Configure the catcher with an error type of TooManyRequestsExceptio
9. I. Configure the next step to be TryAgain.

Correct Answer: C
The best way to implement the Lambda retry functionality is to use the Retry field in the state definition of the GetResource task. The Retry field allows the developer to specify an array of retriers, each with an error type, an interval, and a maximum number of attempts. By setting the error type to TooManyRequestsException, the interval to 10 seconds, and the maximum attempts to 1, the developer can achieve the desired behavior of retrying the GetResource task once after 10 seconds if it encounters
a TooManyRequestsException error. If the retry fails, the state machine will stop running. If the GetResource task encounters an UlegalArgumentException error, the state machine will also stop running without retrying, as this error type is not specified in the Retry field. References
✑ Error handling in Step Functions
✑ Handling Errors, Retries, and adding Alerting to Step Function State Machine Executions
✑ The Jitter Strategy for Step Functions Error Retries on the New Workflow Studio

A developer wants to deploy a new version of an AWS Elastic Beanstalk application. During deployment the application must maintain full capacity and avoid service interruption. Additionally, the developer must minimize the cost of additional resources that support the deployment.
Which deployment method should the developer use to meet these requirements?

1. A. All at once
2. B. Rolling with additional batch
3. C. Bluegreen
4. D. Immutable

Correct Answer: B
This solution will meet the requirements by using a rolling with additional batch deployment method, which deploys the new version of the application to a separate group of instances and then shifts traffic to those instances in batches. This way, the application maintains full capacity and avoids service interruption during deployment, as well as minimizes the cost of additional resources that support the deployment. Option A is not optimal because it will use an all at once deployment method, which deploys the new version of the application to all instances simultaneously, which may cause service interruption or downtime during deployment. Option C is not optimal because it will use a blue/green deployment method, which deploys the new version of the application to a separate environment and then swaps URLs with the original environment, which may incur more costs for additional resources that support the deployment. Option D is not optimal because it will use an immutable deployment method, which deploys the new version of the application to a fresh group of instances and then redirects traffic to those instances, which may also incur more costs for additional resources that support the deployment.
References: AWS Elastic Beanstalk Deployment Policies

A developer at a company recently created a serverless application to process and show data from business reports. The application's user interface (UI) allows users to select and start processing the files. The Ul displays a message when the result is available to view. The application uses AWS Step Functions with AWS Lambda functions to process the files. The developer used Amazon API Gateway and Lambda functions to create an API to support the UI.
The company's Ul team reports that the request to process a file is often returning timeout errors because of the see or complexity of the files. The Ul team wants the API to provide an immediate response so that the Ul can deploy a message while the files are being processed. The backend process that is invoked by the API needs to send an email message when the report processing is complete.
What should the developer do to configure the API to meet these requirements?

1. A. Change the API Gateway route to add an X-Amz-Invocation-Type header win a sialic value of 'Event' in the integration request Deploy the API Gateway stage to apply the changes.
2. B. Change the configuration of the Lambda function that implements the request to process a fil
3. C. Configure the maximum age of the event so that the Lambda function will ion asynchronously.
4. D. Change the API Gateway timeout value to match the Lambda function ominous valu
5. E. Deploy the API Gateway stage to apply the changes.
6. F. Change the API Gateway route to add an X-Amz-Target header with a static value of 'A sync' in the integration request Deploy me API Gateway stage to apply the changes.

Correct Answer: A
This solution allows the API to invoke the Lambda function asynchronously, which means that the API will return an immediate response without waiting for the function to complete. The X-Amz-Invocation-Type header specifies the invocation type of the Lambda function, and setting it to ‘Event’ means that the function will be invoked asynchronously. The function can then use Amazon Simple Email Service (SES) to send an email message when the report processing is complete.
Reference: [Asynchronous invocation], [Set up Lambda proxy integrations in API Gateway]