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Option C is correct because using Auto Scaling groups for the backend services allows the company to scale up or down the number of EC2 instances based on the demand and traffic. This way, the backend services can handle more requests during peak seasons without compromising performance or availability. Using DynamoDB auto scaling allows the company to adjust the provisioned read and write capacity of the table or index automatically based on the actual traffic patterns. This way, the table or index can handle sudden increases or decreases in workload without throttling or overprovisioning1.

Option A is incorrect because migrating the backend services to AWS Lambda may require significant development effort to rewrite the code and test the functionality. Moreover, increasing the read and write capacity of DynamoDB manually may not be efficient or cost-effective, as it does not account for the variability of the workload. The company may end up paying for unused capacity or experiencing throttling if the workload exceeds the provisioned capacity1.

Option B is incorrect because migrating the backend services to AWS Lambda may require significant development effort to rewrite the code and test the functionality. Moreover, configuring DynamoDB to use global tables may not be necessary or beneficial for the company, as global tables are mainly used for replicating data across multiple AWS Regions for fast local access and disaster recovery. Global tables do not automatically scale the provisioned capacity of each replica table; they still require manual or auto scaling settings2.

Option D is incorrect because using Amazon Simple Queue Service (Amazon SQS) and an AWS Lambda function to write to DynamoDB may introduce additional complexity and latency to the application architecture. Amazon SQS is a message queue service that decouples and coordinates the components of a distributed system. AWS Lambda is a serverless compute service that runs code in response to events. Using these services may require significant development effort to integrate them with the backend services and DynamoDB. Moreover, they may not improve the read performance of DynamoDB, which may also be affected by high traffic3.

Auto Scaling groups

DynamoDB auto scaling

AWS Lambda

DynamoDB global tables

AWS Lambda vs EC2: Comparison of AWS Compute Resources - Simform

Managing throughput capacity automatically with DynamoDB auto scaling - Amazon DynamoDB

AWS Aurora Global Database vs. DynamoDB Global Tables

Amazon Simple Queue Service (SQS)

•Use Amazon S3 for web hosting with AWS AppSync for database API services. Use Amazon Simple Queue Service (Amazon SQS) for order queuing. Use AWS Lambda for business logic with an Amazon SQS dead-letter queue for retaining failed orders.

This solution will allow you to:

•Host a static website on Amazon S3 without provisioning or managing servers1.

•Use AWS AppSync to create a scalable GraphQL API that connects to your database and other data sources1.

•Use Amazon SQS to decouple and scale your order processing microservices1.

•Use AWS Lambda to run code for your business logic without provisioning or managing servers1.

•Use an Amazon SQS dead-letter queue to retain messages that can’t be processed by your Lambda function1.

The correct answer is D.

D. This solution meets the requirements because it uses a scheduled scaling policy for the EC2 instances, which can adjust the capacity according to the known sale events. It also uses Amazon Aurora PostgreSQL Multi-AZ DB cluster, which provides high availability and durability for the database. It uses Amazon EventBridge rules and AWS Lambda functions to create a larger Aurora Replica before a sale event and fail over to it, which can improve the performance and handle the increased traffic.It also uses anotherEventBridge rule and Lambda function to scale down the Aurora Replica after the sale event, which can save costs123

A. This solution is incorrect because it uses predictive scaling policy for the EC2 instances, which is not suitable for one-time events that are scheduled. Predictive scaling is based on historical data and machine learning, which may not accurately forecast the demand for sale events. It also uses Amazon Aurora PostgreSQL Serverless v2 Multi-AZ DB instance, which does not support read replicas.The use of AWS Step Functions state machine and Lambda functions to pre-warm the database is unnecessary and adds complexity45

B. This solution is incorrect because it uses Amazon RDS for PostgreSQL Multi-AZ DB instance with automatically scaling read replicas, which may not provide enough performance improvement for the sale events. The use of EventBridge rules and Lambda functions to create a larger read replica and fail over to it is risky and may cause downtime ordata loss.The use of another EventBridge rule and Lambda function to scale down the read replica is also risky and may cause inconsistency or data loss67

C. This solution is incorrect because it uses predictive scaling policy for the EC2 instances, which is not suitable for one-time events that are scheduled. Predictive scaling is based on historical data and machine learning, which may not accurately forecast the demand for sale events.The use of AWS Step Functions state machine and Lambda functions to pre-warm the database is unnecessary and adds complexity45

Using a DHCP options set in AWS allows EC2 instances to automatically receive network configuration information, including the IP address of the on-premises NTP server.

This ensures that all EC2 instances in the VPC consistently use the on-premises atomic clock as their authoritative time source, maintaining the same time synchronization as the existing environment.

By allowing NTP traffic over the Direct Connect connection and ensuring proper security group and network ACL configurations, this approach eliminates the need to manually configure each EC2 instance’s NTP settings, significantly reducing administrative overhead and ensuring consistent, accurate time across the environment.

This aligns with AWS best practices for extending on-premises time synchronization to EC2 instances in a hybrid environment.