- (Topic 4)
A company is running a photo hosting service in the us-east-1 Region. The service enables users across multiple countries to upload and view photos. Some photos are heavily viewed for months, and others are viewed for less than a week. The application allows uploads of up to 20 MB for each photo. The service uses the photo metadata to determine which photos to display to each user.
Which solution provides the appropriate user access MOST cost-effectively?

1. A. Store the photos in Amazon DynamoD
2. B. Turn on DynamoDB Accelerator (DAX) to cache frequently viewed items.
3. C. Store the photos in the Amazon S3 Intelligent-Tiering storage clas
4. D. Store the photo metadata and its S3 location in DynamoDB.
5. E. Store the photos in the Amazon S3 Standard storage clas
6. F. Set up an S3 Lifecycle policy to move photos older than 30 days to the S3 Standard-Infrequent Access (S3 Standard-IA) storage clas
7. G. Use the object tags to keep track of metadata.
8. H. Store the photos in the Amazon S3 Glacier storage clas
9. I. Set up an S3 Lifecycle policy to move photos older than 30 days to the S3 Glacier Deep Archive storage clas
10. J. Store the photo metadata and its S3 location in Amazon OpenSearch Service.

Correct Answer: B
This solution provides the appropriate user access most cost-effectively
because it uses the Amazon S3 Intelligent-Tiering storage class, which automatically optimizes storage costs by moving data to the most cost-effective access tier when access patterns change, without performance impact or operational overhead1. This storage class is ideal for data with unknown, changing, or unpredictable access patterns, such as photos that are heavily viewed for months or less than a week. By storing the photo metadata and its S3 location in DynamoDB, the application can quickly query and retrieve the relevant photos for each user. DynamoDB is a fast, scalable, and fully managed NoSQL database service that supports key-value and document data models2.
References: 1: Amazon S3 Intelligent-Tiering Storage Class | AWS3, Overview section2: Amazon DynamoDB - NoSQL Cloud Database Service4, Overview section.

- (Topic 3)
A company is moving its data management application to AWS. The company wants to transition to an event-driven architecture. The architecture needs to the more distributed and to use serverless concepts whit performing the different aspects of the workflow. The company also wants to minimize operational overhead.
Which solution will meet these requirements?

1. A. Build out the workflow in AWS Glue Use AWS Glue to invoke AWS Lambda functions to process the workflow slaps
2. B. Build out the workflow in AWS Step Functions Deploy the application on Amazon EC2 Instances Use Step Functions to invoke the workflow steps on the EC2 instances
3. C. Build out the workflow in Amazon EventBridg
4. D. Use EventBridge to invoke AWS Lambda functions on a schedule to process the workflow steps.
5. E. Build out the workflow m AWS Step Functions Use Step Functions to create a stale machine Use the stale machine to invoke AWS Lambda functions to process the workflow steps

Correct Answer: D
This answer is correct because it meets the requirements of transitioning to an event-driven architecture, using serverless concepts, and minimizing operational overhead. AWS Step Functions is a serverless service that lets you coordinate multiple AWS services into workflows using state machines. State machines are composed of tasks and transitions that define the logic and order of execution of the workflow steps. AWS Lambda is a serverless function-as-a-service platform that lets you run code without provisioning or managing servers. Lambda functions can be invoked by Step Functions as tasks in a state machine, and can perform different aspects of the data management workflow, such as data ingestion, transformation, validation, and analysis. By using Step Functions and Lambda, the company can benefit from the following advantages:
✑ Event-driven: Step Functions can trigger Lambda functions based on events, such as timers, API calls, or other AWS service events. Lambda functions can also emit events to other services or state machines, creating an event-driven architecture.
✑ Serverless: Step Functions and Lambda are fully managed by AWS, so the company does not need to provision or manage any servers or infrastructure. The company only pays for the resources consumed by the workflows and functions, and can scale up or down automatically based on demand.
✑ Operational overhead: Step Functions and Lambda simplify the development and deployment of workflows and functions, as they provide built-in features such as monitoring, logging, tracing, error handling, retry logic, and security. The company can focus on the business logic and data processing rather than the operational details.
References:
✑ What is AWS Step Functions?
✑ What is AWS Lambda?

- (Topic 4)
A company plans to use Amazon ElastiCache for its multi-tier web application. A solutions architect creates a Cache VPC for the ElastiCache cluster and an App VPC for the application’s Amazon EC2 instances. Both VPCs are in the us-east-1 Region.
The solutions architect must implement a solution to provide the application’s EC2 instances with access to the ElastiCache cluster.
Which solution will meet these requirements MOST cost-effectively?

1. A. Create a peering connection between the VPC
2. B. Add a route table entry for the peering connection in both VPC
3. C. Configure an inbound rule for the ElastiCache cluster’s security group to allow inbound connection from the application’s security group.
4. D. Create a Transit VP
5. E. Update the VPC route tables in the Cache VPC and the App VPC to route traffic through the Transit VP
6. F. Configure an inbound rule for the ElastiCache cluster's security group to allow inbound connection from the application’s security group.
7. G. Create a peering connection between the VPC
8. H. Add a route table entry for the peering connection in both VPC
9. I. Configure an inbound rule for the peering connection’s security group to allow inbound connection from the application’s security group.
10. J. Create a Transit VP
11. K. Update the VPC route tables in the Cache VPC and the App VPC to route traffic through the Transit VP
12. L. Configure an inbound rule for the Transit VPC’s security group to allow inbound connection from the application’s security group.

Correct Answer: A
Creating a peering connection between the VPCs allows the application's EC2 instances to communicate with the ElastiCache cluster directly and efficiently. This is the most cost- effective solution as it does not involve creating additional resources such as a Transit VPC, and it does not incur additional costs for traffic passing through the Transit VPC. Additionally, it is also more secure as it allows you to configure a more restrictive security group rule to allow inbound connection from only the application's security group.

- (Topic 3)
A company runs a web application on Amazon EC2 instances in multiple Availability Zones. The EC2 instances are in private subnets. A solutions architect implements an internet- facing Application Load Balancer (ALB) and specifies the EC2 instances as the target group. However, the internet traffic is not reaching the EC2 instances.
How should the solutions architect reconfigure the architecture to resolve this issue?

1. A. Replace the ALB with a Network Load Balance
2. B. Configure a NAT gateway in a public subnet to allow internet traffic.
3. C. Move the EC2 instances to public subnet
4. D. Add a rule to the EC2 instances’ security groups to allow outbound traffic to 0.0.0.0/0.
5. E. Update the route tables for the EC2 instances’ subnets to send 0.0.0.0/0 traffic through the internet gateway rout
6. F. Add a rule to the EC2 instances’ security groups to allow outbound traffic to 0.0.0.0/0.
7. G. Create public subnets in each Availability Zon
8. H. Associate the public subnets with the AL
9. I. Update the route tables for the public subnets with a route to the private subnets.

Correct Answer: D
https://aws.amazon.com/premiumsupport/knowledge-center/public-load-balancer-private-ec2/

- (Topic 3)
A company provides an online service for posting video content and transcoding it for use by any mobile platform. The application architecture uses Amazon Elastic File System (Amazon EFS) Standard to collect and store the videos so that multiple Amazon EC2 Linux instances can access the video content for processing As the popularity of the service has grown over time, the storage costs have become too expensive.
Which storage solution is MOST cost-effective?

1. A. Use AWS Storage Gateway for files to store and process the video content
2. B. Use AWS Storage Gateway for volumes to store and process the video content
3. C. Use Amazon EFS for storing the video content Once processing is complete transfer the files to Amazon Elastic Block Store (Amazon EBS)
4. D. Use Amazon S3 for storing the video content Move the files temporarily over to an Amazon Elastic Block Store (Amazon EBS) volume attached to the server for processing

Correct Answer: D
• Amazon S3 for large-scale, durable, and inexpensive storage of the video content. S3 storage costs are significantly lower than EFS. • Amazon EBS only temporarily during processing. By mounting an EBS volume only when a video needs to be processed, and unmounting it after, the time the content spends on the higher-cost EBS storage is minimized. • The EBS volume can be sized to match the workload needs for active processing, keeping costs lower. The volume does not need to store the entire video library long-term.