A company is designing a cost-optimization strategy for its application on AWS. The applic… — AWS Certified Solutions Architect - Associate

A company is designing a cost-optimization strategy for its application on AWS. The application consists of the following components:
- A fleet of Amazon EC2 instances running a web backend that operates $24/7$ with a steady-state requirement of $10$ instances, scaling up during peak hours.
- An Amazon RDS for PostgreSQL database instance that operates $24/7$ .
- A data transformation batch job running on EC2 instances in a private subnet. The job runs daily, is fault-tolerant, and downloads massive amounts of daily transaction logs from Amazon S3.

Which combination of options is the MOST cost-effective for these requirements?

A
Purchase a Compute Savings Plan to cover both the baseline EC2 instances and the Amazon RDS database instance, use Spot Instances for the batch job EC2 instances, and create a Gateway VPC endpoint for Amazon S3.
B
Migrate the continuous $24/7$ web backend to AWS Lambda functions, use Spot Instances for the batch job EC2 instances, purchase RDS Reserved Instances for the database, and create a Gateway VPC endpoint for Amazon S3.
Purchase a Compute Savings Plan to cover the baseline EC2 instances, use Spot Instances for the batch job EC2 instances, purchase RDS Reserved Instances for the database, and create a Gateway VPC endpoint for Amazon S3.Answer
D
Purchase a Compute Savings Plan to cover the baseline EC2 instances, use Spot Instances for the batch job EC2 instances, purchase RDS Reserved Instances for the database, and route the S3 data transfer through a NAT Gateway.

Answer

The most cost-effective option is to purchase a Compute Savings Plan for the baseline EC2 instances, use Spot Instances for the batch job, purchase RDS Reserved Instances for the database, and create a Gateway VPC endpoint for Amazon S3.

The correct strategy combines a Compute Savings Plan for the baseline EC2 instances, Spot Instances for the interruptible batch job, RDS Reserved Instances for the 24/7 database, and a Gateway VPC endpoint to avoid NAT Gateway data processing charges for S3 traffic.

Step-by-Step Solution

Analyze compute baseline optimization

Identify that the 24/7 steady-state EC2 instances can be covered by a Compute Savings Plan to maximize savings.

Compute Savings Plans provide a significant discount for consistent, steady-state compute usage over a 1-year or 3-year term.

Select purchasing model for the batch job

Select Spot Instances for the EC2 instances running the data transformation batch job.

Since the batch job is fault-tolerant and can run at any time, Spot Instances offer the lowest cost (up to 90% off On-Demand) and can handle interruptions.

Optimize the database costs

Select RDS Reserved Instances for the 24/7 PostgreSQL database.

Reserved Instances provide a significant discount for database instances that run continuously 24/7.

Minimize data transfer costs to S3

Choose a Gateway VPC endpoint for Amazon S3 instead of routing traffic through a NAT Gateway.

A Gateway VPC endpoint is free and allows traffic to traverse privately directly to S3, avoiding expensive NAT Gateway data processing charges.

Key Concept

Selecting cost-optimized purchasing strategies (Compute Savings Plans, Spot, Reserved Instances) and optimizing network traffic pathways to avoid NAT Gateway charges.

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

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