Free Amazon Web Services DVA-C02 Practice Exam with Questions & Answers | Set: 7

This is a frequent trouble. Web applications cannot access the resources in other domains by default, except some exceptions. You must configure CORS on the resources to be accessed. https://docs.aws.amazon.com/AmazonS3/latest/userguide/cors.html

Amazon DynamoDB is a fully managed NoSQL database service that can store and retrieve any amount of data with high availability and performance. DynamoDB can handle concurrent requests from multiple IoT devices without throttling or data loss. To prevent duplicate requests from causing inconsistencies or data loss, the Lambda function can use DynamoDB conditional writes to check if the unique identifier for each request already exists in the table before processing the request. If the identifier exists, the function can skip or abort the request; otherwise, it can process the request and store the identifier in the table. Reference: Using conditional writes

Comprehensive and Detailed Step-by-Step Explanation:

Option A: Use Amazon S3 for Shared Test Events:

Storing JSON test event files in an S3 bucket provides a centralized, cost-effective, and highly available solution.

Granular IAM policies can restrict access to specific developers or roles, ensuring security while maintaining consistency for shared test events.

This solution has minimal operational overhead and integrates easily with existing workflows.

Why Other Options Are Incorrect:

Option B: Using DynamoDB and a Lambda function introduces unnecessary complexity for a relatively simple requirement. S3 provides a simpler and more cost-efficient solution.

Option C: AWS Lambda test events are not inherently shareable across developers, making this option invalid.

Option D: Using a Git repository adds operational overhead and requires developers to clone/update repositories for access, which is more cumbersome compared to S3.

References:

Amazon S3 for Centralized Storage

Comprehensive and Detailed Step-by-Step Explanation:

Option C: Use AWS CodePipeline for CI/CD Workflow:

AWS CodePipeline automates the entire CI/CD pipeline, including build, deploy, and test stages. This minimizes manual effort and integrates well with AWS services.

API Gateway Stages: Represent different environments, such as dev, test, and prod, allowing isolated deployment and testing.

AWS CloudFormation Templates: Ensure that the infrastructure for Lambda and API Gateway is consistent across environments.

AWS CodeBuild for Automated Tests: Validates the deployments in each stage, ensuring integration and functionality are tested post-deployment.

Why Other Options Are Incorrect:

Option A and B: While using AWS SAM or CloudFormation for infrastructure management is valid, these options lack the fully automated CI/CD pipeline provided by CodePipeline.

Option D: Manually invoking Lambda functions using the AWS CLI introduces operational overhead and lacks the automation provided by CodePipeline.

References:

AWS CodePipeline Documentation

API Gateway Stages for CI/CD

API Gateway Stages: Stages in API Gateway represent distinct environments (like PROD and DEV) allowing different configurations.

Stage Variables: Stage variables store environment-specific information, including Lambda function aliases.

Ease of Management: This solution offers a straightforward way to manage different Lambda function versions across environments.

References:

API Gateway Stages: https://docs.aws.amazon.com/apigateway/latest/developerguide/set-up-stages.html

API Gateway Stage Variables: https://docs.aws.amazon.com/apigateway/latest/developerguide/stage-variables.html

Amazon API Gateway supports mock integration responses, which are predefined responses that can be returned without sending requests to a backend service. Mock integration responses can be used for testing or prototyping purposes, or for simulating different backend responses based on certain conditions. A request mapping template can be used to select a mock integration response based on an expression that evaluates some aspects of the request, such as headers, query strings, or body content. This solution does not require any additional resources or code changes and has the least operational overhead. Reference: Set up mock integrations for an API Gateway REST API

https://docs.aws.amazon.com/apigateway/latest/developerguide/how-to-mock-integration.html

Default SSE in DynamoDB: DynamoDB tables are encrypted at rest by default using an AWS owned key (SSE-S3).

No Additional Action Needed: Creating a table without explicitly specifying a KMS key will use this default encryption.

References:

DynamoDB Server-Side Encryption: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Encryption

Step 1: Understanding the Requirements

Best Practices for Security:

Minimize the use of hardcoded credentials or long-lived access keys.

Use IAM roles for EC2 instances to securely grant permissions to applications running on the instance.

Access Scope: The application needs read-only access to an S3 bucket.

Step 2: Solution Analysis

Option A:

Define an IAM policy with the required s3:GetObject permissions.

Attach this policy to an IAM role.

Assign the role to the EC2 instance profile.

This approach follows security best practices by eliminating the need for static credentials and using temporary, scoped credentials provided by the instance profile.

Correct option.

Option B:

IAM groups are used for organizing users, not for EC2 instances or instance profiles.

Not suitable.

Option C:

IAM users are associated with specific individuals or applications and require static credentials.

This violates security best practices for temporary credentials and roles.

Not suitable.

Option D:

IAM web identity federation is used for applications that authenticate users via third-party identity providers.

This is unnecessary for EC2 instances and does not align with the requirements.

Not suitable.

Step 3: Implementation Steps

Create an IAM Policy:

Grant read-only access to the S3 bucket:

json

Copy code

{

"Version": "2012-10-17",

"Statement": [

{

"Effect": "Allow",

"Action": "s3:GetObject",

"Resource": "arn:aws:s3:::your-bucket-name/*"

}

]

}

Attach the Policy to an IAM Role:

Create an IAM role and attach the policy to the role.

Associate the Role with the EC2 Instance:

Attach the role to the instance profile used by the EC2 instance.

AWS Developer References:

IAM Roles for Amazon EC2

Amazon S3 Permissions Reference