SAA-C03 Design Cost-Optimized Architectures — 10 Questions

Question 1

You store application logs in an S3 bucket. After 30 days, the logs are rarely accessed, but you must retain them for 1 year for compliance. Which S3 feature is the best way to reduce storage cost while meeting the retention requirement?

Accepted Answer

Create an S3 lifecycle rule to transition older objects to a colder storage class after 30 days, then expire after 1 year. Option A is correct because an S3 Lifecycle rule can automatically transition objects from S3 Standard to a colder storage class (e.g., S3 Glacier Instant Retrieval or S3 Glacier Deep Archive) after 30 days, reducing storage costs for rarely accessed logs. After 1 year, the rule can expire the objects, which permanently deletes them, meeting the compliance retention requirement without manual intervention.

Answer

Keep all logs in S3 Standard and rely on lower request rates to reduce cost

Answer

Copy logs to EBS snapshots each week and delete the original files

Answer

Use S3 replication to a second bucket in another region to reduce costs

Question 2

CloudWatch metrics show your EC2 instances have average CPU utilization around 10% with stable performance over several weeks. The application does not require additional headroom right now. What is the most effective cost-optimization action?

Accepted Answer

Right-size the instances to a smaller size that matches the observed utilization. Right-sizing EC2 instances to match observed utilization is the most effective cost-optimization action because the current instances are over-provisioned (average CPU at 10%). By selecting a smaller instance type that aligns with the actual workload, you reduce hourly costs without impacting performance, as the application has stable behavior and no need for headroom.

Answer

Increase the Auto Scaling desired capacity to add more instances

Answer

Switch to Spot Instances immediately even though interruptions would impact users

Answer

Disable detailed monitoring to reduce CPU usage from the monitoring agent

Question 3

A marketing site serves versioned JavaScript and CSS files from Amazon S3 through CloudFront. The origin bill is rising because CloudFront keeps fetching the same files too often, and the application never changes a file at the same URL once it is published. Which two changes should you make? Select two.

Accepted Answer

Set long-lived Cache-Control headers, such as a high max-age and immutable policy, on the versioned assets.. Option A is correct because setting long-lived Cache-Control headers (e.g., `max-age=31536000` and `immutable`) on versioned assets tells CloudFront and browsers to cache the files aggressively. Since the application never changes a file at the same URL, this eliminates redundant origin fetches, directly reducing the origin bill.

Answer

Move the static assets to an EC2 web server behind an Application Load Balancer.

Answer

Disable CloudFront caching so every request always reaches the origin.

Answer

Add more viewer-facing headers to the cache key so each browser variation gets a unique cached object.

Question 4

An application serves static images through Amazon CloudFront. The team observes higher-than-expected origin fetches, which increases origin bandwidth costs. Which change most directly improves CloudFront cache reuse to reduce origin requests for the static content?

Accepted Answer

Set appropriate Cache-Control headers (or origin cache settings) so CloudFront caches responses longer. Option A is correct because setting appropriate Cache-Control headers (e.g., max-age or s-maxage) or configuring origin cache settings tells CloudFront how long to keep objects in its edge cache before revalidating with the origin. By extending the cache duration, CloudFront serves more requests from its cache, reducing the number of origin fetches and lowering bandwidth costs.

Answer

Disable caching for the distribution so every request goes back to the origin

Answer

Configure CloudFront to forward all request headers and query strings to the origin

Answer

Move the S3 bucket to a different AWS Region, without changing CloudFront caching behavior

Question 5

Your team runs a batch processing workload on EC2 that can tolerate interruptions. If an instance is terminated, the job can restart from checkpoints. To reduce compute costs, what is the most cost-optimized approach?

Accepted Answer

Use EC2 Spot Instances for the batch workers. Spot Instances are ideal for fault-tolerant, interruption-tolerant batch workloads because they offer significant cost savings (up to 90% compared to On-Demand) while allowing the job to resume from checkpoints if terminated. This aligns perfectly with the requirement to reduce compute costs without compromising the ability to restart interrupted jobs.

Answer

Use Dedicated Hosts to ensure capacity for the cheapest instance

Answer

Use On-Demand instances and schedule extra runs to offset interruptions

Answer

Use Reserved Instances only, because they eliminate instance termination events

Question 6

An internal rendering job runs on EC2 workers in an Auto Scaling group. Each job writes checkpoints every few minutes to S3 and can resume from the latest checkpoint after an interruption. The queue depth varies sharply, and the team wants the lowest possible compute cost. Which two changes should they make? Select two.

Accepted Answer

Run the worker fleet on EC2 Spot Instances.. Option A is correct because Spot Instances can be interrupted with a two-minute warning, and since the rendering job writes checkpoints to S3 every few minutes and can resume from the latest checkpoint, it is fault-tolerant to interruptions. This allows the team to leverage the significantly lower cost of Spot Instances (up to 90% off On-Demand) while maintaining job completion, achieving the lowest compute cost for variable queue depths.

Answer

Purchase Dedicated Hosts so the fleet keeps physical servers reserved for the workload.

Answer

Run the entire fleet on On-Demand Instances to avoid any interruption risk.

Answer

Move the workers to AWS Outposts to keep compute close to the data.

Question 7

A company has a steady, predictable workload that must run continuously (24/7) in a single AWS Region. The team wants the lowest cost option available for this steady usage, but also expects they may choose different EC2 instance families in the future (without re-buying compute discounts). Which AWS purchase option best meets these goals?

Accepted Answer

Compute Savings Plans, committed for a 1- to 3-year term in the Region. Compute Savings Plans offer the lowest cost for steady, predictable workloads while providing instance family flexibility within a Region. Unlike Reserved Instances, they automatically apply discounts to any EC2 instance family (and even Fargate/Lambda) in the chosen Region, so the company can switch instance families in the future without losing the discount. A 1- or 3-year commitment yields significant savings (up to 66%) compared to On-Demand, making it the optimal choice for this scenario.

Answer

On-Demand Instances only, because they automatically adjust to future needs

Answer

Standard Reserved Instances tied to a single instance type and Availability Zone

Answer

EC2 Spot Instances, because they are always cheaper than savings programs

Question 8

Match each data-retention scenario to the most cost-effective Amazon S3 storage class. Assume the retrieval pattern and access-latency requirement are the most important constraints.

Question 9

A web service runs continuously on AWS 24/7. The team expects steady compute usage for the next 12–24 months, but may change instance families/sizes as performance tuning continues. Which purchase option best reduces cost while keeping flexibility to change instance types?

Accepted Answer

Use Compute Savings Plans for the expected steady usage. Compute Savings Plans offer the lowest prices (up to 66% off On-Demand) in exchange for a commitment to a consistent amount of compute usage (measured in $/hour) for a 1- or 3-year term. Unlike Reserved Instances, they automatically apply to any EC2 instance family, size, OS, or region, giving you the flexibility to change instance types as performance tuning evolves, while still reducing costs for steady-state workloads.

Answer

Buy EC2 On-Demand instances and rely on future Spot capacity for discounts

Answer

Buy Reserved Instances with a fixed instance type and region

Answer

Buy Spot Instances and stop scaling to avoid interruption risk

Question 10

Match each workload to the AWS pricing option that most directly minimizes cost while still meeting the stated flexibility requirements. Use each option once.