SAA-C03 Design Cost-Optimized Architectures Practice Test 3 — 15 Questions

Question 1

An application runs on EC2 in us-east-1 and frequently reads objects from an S3 bucket that is physically located in us-west-2. The finance team reports unexpectedly high inter-Region data transfer charges because the application retrieves objects for many user requests. A constraint: the bucket in us-west-2 must remain the system of record for compliance, but the application can read from a replica in us-east-1.

What should the solutions architect do to minimize network spend while meeting the compliance constraint?

Accepted Answer

Enable S3 Cross-Region Replication from the us-west-2 source bucket to a destination bucket in us-east-1, and update the app to read from the us-east-1 bucket.. Option A is correct because S3 Cross-Region Replication (CRR) automatically replicates objects from the source bucket in us-west-2 to a destination bucket in us-east-1, satisfying the compliance requirement that the us-west-2 bucket remains the system of record. By updating the application to read from the us-east-1 bucket, all read traffic stays within the same region, eliminating inter-region data transfer charges for object retrievals. This approach directly addresses the cost issue while preserving the original bucket as the authoritative source.

Answer

Create an interface VPC endpoint for S3 in us-east-1 and keep all object reads pointing to the us-west-2 bucket.

Answer

Use VPC peering between two regions and route all requests to the us-west-2 bucket over the peering link.

Answer

Use Route 53 latency-based routing to send users to a us-west-2 web endpoint and keep the S3 bucket unchanged.

Question 2

A SaaS company uses an S3 bucket for database backups created daily. Backups are rarely restored; the company’s documented RTO is 24 hours, and the compliance policy requires backups be kept for 90 days. The team currently stores all backups in S3 Standard, which is costly.

Which single lifecycle policy change is most cost-optimized while still meeting the 24-hour RTO and 90-day retention?

Accepted Answer

Add a lifecycle rule to transition backups older than 1 day to S3 Glacier Flexible Retrieval, and keep them until day 90.. Option A is correct because S3 Glacier Flexible Retrieval offers retrieval times ranging from minutes to hours, which comfortably meets the 24-hour RTO, while providing significant cost savings over S3 Standard for data that is rarely accessed. Transitioning backups older than 1 day to this storage class reduces costs without compromising the 90-day retention requirement.

Answer

Add a lifecycle rule to transition backups older than 1 day to S3 Glacier Instant Retrieval, and keep them until day 90.

Answer

Add a lifecycle rule to transition backups older than 1 day to S3 Glacier Deep Archive, and keep them until day 90 with no restore configuration.

Answer

Add a lifecycle rule to transition backups older than 1 day to S3 One Zone-IA, and delete them after 7 days.

Question 3

A media company runs a batch job that processes image thumbnails. The job can be restarted from checkpoints and does not have user-facing SLAs. The batch capacity can tolerate interruptions. Which EC2 purchasing option is the best cost optimization choice?

Accepted Answer

Use EC2 Spot Instances, accepting the possibility of interruptions and using checkpoints to resume.. Spot Instances offer significant cost savings (up to 90% compared to On-Demand) and are ideal for fault-tolerant, stateless, or checkpointable workloads. Since the batch job can restart from checkpoints and tolerates interruptions, Spot Instances provide the best cost optimization without compromising functionality.

Answer

Use On-Demand Instances because interruptions are not allowed for production workloads.

Answer

Purchase Reserved Instances because they provide a discount regardless of the workload timing.

Answer

Buy Savings Plans because they guarantee capacity and remove the risk of interruptions entirely.

Question 4

A data engineering team runs a nightly ETL job on EC2. The job can be checkpointed every 5 minutes and can be retried from the last checkpoint if the instance terminates. The job runtime varies from 2 to 4 hours, and the team has no need for a specific instance type, as long as it completes before 7:00 AM local time. They currently run the job on On-Demand EC2, leading to high monthly compute cost.

Which change best reduces cost while maintaining the business deadline?

Accepted Answer

Use Spot Instances for the ETL workload, and configure the job to checkpoint frequently and restart on interruption.. Spot Instances offer significant cost savings (up to 90%) compared to On-Demand, and the ETL job's ability to checkpoint every 5 minutes and restart from the last checkpoint makes it resilient to Spot interruptions. This allows the team to meet the 7:00 AM deadline while drastically reducing compute costs, as the job can be retried on new Spot capacity if interrupted.

Answer

Use Reserved Instances with a 1-year term to lower costs, since reservations provide discounts for any usage.

Answer

Switch to On-Demand but enable Auto Scaling so the job finishes faster during peak hours.

Answer

Use Spot Instances but disable checkpointing to simplify the application.

Question 5

A startup has a stable production web service that runs continuously (24/7) on AWS. They have consistent compute requirements for the next 1 year, but the instance size and family might change as they optimize performance. To reduce cost while maintaining flexibility across instance types, which purchasing option should they consider?

Accepted Answer

Compute Savings Plans. Compute Savings Plans offer the lowest prices (up to 66% off On-Demand) while allowing flexibility to change instance family, size, OS, and region. This matches the startup's need for consistent 1-year compute usage with potential instance type changes during optimization.

Answer

Reserved Instances with a fixed instance type

Answer

Spot Instances

Answer

On-Demand Instances

Question 6

A company stores compliance reports in Amazon S3. Objects are written once and rarely accessed. They need to keep the data for 3 years. When retrieval is needed for an audit, the reports can be restored within hours (not minutes). What storage class should the company use for new objects, assuming minimal operational overhead?

Accepted Answer

S3 Glacier Flexible Retrieval. S3 Glacier Flexible Retrieval is the correct choice because it is designed for long-term archival data that is rarely accessed, with retrieval times ranging from minutes to hours. It offers a lower storage cost than S3 Standard while still meeting the 3-year retention requirement and the acceptable retrieval window of 'within hours'. This minimizes operational overhead as objects are automatically transitioned to the appropriate storage tier without manual lifecycle management.

Answer

S3 Standard

Answer

S3 Intelligent-Tiering

Answer

S3 Glacier Deep Archive

Question 7

A marketing team runs a report-generation process that must execute once per day at 02:00 UTC. It usually completes in 10315 minutes, but sometimes takes up to 45 minutes due to varying data volumes. They currently run the workload on an EC2 instance that is always on, which wastes money during off-hours. The team wants to minimize operational overhead and pay mainly for actual execution time.

What is the best architecture choice?

Accepted Answer

Use an EventBridge schedule to run the report as an Amazon ECS task on AWS Fargate and write results to S3.. Amazon ECS on AWS Fargate is the best choice because it eliminates the need to manage servers, scales automatically, and charges only for the vCPU and memory resources consumed during task execution. The EventBridge schedule triggers the Fargate task at 02:00 UTC, and the report is written to S3, which provides durable, cost-effective storage. This architecture minimizes operational overhead and cost by avoiding an always-on EC2 instance.

Answer

Use a scheduled Amazon EC2 Auto Scaling group that keeps a minimum of one instance running at all times.

Answer

Use AWS Lambda triggered by an EventBridge schedule at 02:00 UTC and write results to S3.

Answer

Use an EMR cluster provisioned daily with manual teardown to ensure the instance is always available before 02:00.

Question 8

A company keeps daily database backups in an S3 bucket. They may restore from backups during the first 30 days if there is an issue. After 30 days, backups are rarely restored, but must be retained for 2 years. Which lifecycle strategy most cost-effectively meets these requirements?

Accepted Answer

Use an S3 lifecycle policy to keep backups in S3 Standard for 30 days, then transition them to S3 Glacier Deep Archive for the remainder of the 2-year retention period.. Option C is correct because it balances cost and compliance: backups are kept in S3 Standard for the first 30 days when restores are frequent, ensuring low-latency access, then transitioned to S3 Glacier Deep Archive for the remaining retention period. S3 Glacier Deep Archive offers the lowest storage cost (approximately $0.00099/GB/month) for long-term retention, and the lifecycle policy automates the transition without manual intervention. This approach minimizes storage costs while meeting the 2-year retention requirement.

Answer

Delete backups after 30 days to avoid storage costs, since restores are rare.

Answer

Keep all backups in S3 Standard for the entire 2-year retention period.

Answer

Move backups to S3 Glacier Deep Archive immediately after creation, even for the first 30 days.

Question 9

A media company runs a 24/7 recommendation engine on EC2 in one AWS Region. The workload is interruption-intolerant, and the team expects steady usage but may change instance families and sizes during planned optimizations. Compared to the current On-Demand setup, they want the lowest cost while avoiding the rigidity of locking to a specific instance type.

What should the solutions architect recommend?

Accepted Answer

Purchase a Compute Savings Plan for the expected steady hourly usage in that Region.. B is correct because a Compute Savings Plan offers the lowest cost for steady-state workloads without locking to a specific instance type, providing up to 66% discount compared to On-Demand while allowing flexibility to change instance families, sizes, OS, or tenancy within a Region. This matches the requirement for cost savings and flexibility during planned optimizations.

Answer

Switch the instances to Spot Instances and use interruption handling because it is the largest discount.

Answer

Purchase a Standard Reserved Instance tied to a single specific instance type for the next 3 years.

Answer

Keep On-Demand and rely on Auto Scaling to reduce capacity when utilization is low.

Question 10

An internal team runs a report-generation job once per day. It typically finishes in a few minutes, and even on its slowest days it still completes in under 15 minutes. The team wants to reduce operational overhead and pay primarily for actual runtime instead of keeping servers running 24/7. Which AWS approach best matches these goals?

Accepted Answer

Use AWS Lambda triggered by a schedule (for example, EventBridge) to run the report at the required time.. AWS Lambda, triggered by Amazon EventBridge (CloudWatch Events), is ideal for short-lived, infrequent jobs like this daily report. It eliminates idle server costs by running only when invoked, and the 15-minute execution timeout comfortably covers the job's maximum runtime. This serverless approach directly reduces operational overhead and aligns with a pay-per-use cost model.

Answer

Deploy the job on EC2 instances and keep them running continuously for the daily schedule.

Answer

Run the job in an RDS database using stored procedures scheduled by the database engine.

Answer

Use an Auto Scaling group with a fixed minimum size of one instance and disable scaling.

Question 11

A startup runs two EC2-based workloads in the same AWS Region. Its customer-facing API is always on, and its nightly video transcoding fleet can restart jobs from checkpoints if an instance is interrupted. The finance team wants the lowest monthly compute cost without changing the application design. Which two actions should the team take? Select two.

Accepted Answer

Buy a Compute Savings Plan to cover the always-on API baseline usage.. Option B is correct because a Compute Savings Plan offers the lowest cost for steady-state workloads like the always-on API, providing up to 66% savings over On-Demand in exchange for a 1- or 3-year commitment. It applies to any EC2 instance family within a Region, making it flexible and cost-effective for the baseline usage. Option C is correct because Spot Instances can be up to 90% cheaper than On-Demand and are ideal for fault-tolerant workloads like the transcoding fleet, which can resume from checkpoints if interrupted.

Answer

Purchase an All Upfront Reserved Instance for the transcoding fleet only.

Answer

Increase the API instance size so CPU utilization stays below 30 percent.

Answer

Move the API tier to Dedicated Hosts to improve isolation and lower spend.

Question 12

A team runs an Amazon NLB in a VPC with targets registered in multiple Availability Zones (AZs). Their bill shows high inter-AZ data transfer charges. They want to reduce unnecessary cross-AZ traffic costs while still maintaining healthy targets per AZ. What change is most likely to reduce inter-AZ charges?

Accepted Answer

Disable cross-zone load balancing on the NLB so each client is routed to targets in the same AZ when possible.. Option A is correct because disabling cross-zone load balancing on an NLB ensures that each client is routed only to targets within the same Availability Zone as the NLB node that receives the traffic. This eliminates inter-AZ data transfer charges because traffic never leaves the AZ boundary. The NLB still maintains healthy targets per AZ by distributing traffic only among healthy targets within that AZ.

Answer

Enable cross-zone load balancing so all targets receive traffic from every AZ.

Answer

Move the NLB to a different Region so traffic is always kept local.

Answer

Replace the NLB with a NAT gateway to reduce data charges between AZs.

Question 13

A company stores application logs in an S3 bucket. They retain logs for 180 days. Compliance requires that the logs be immutable once written, but the business only reviews logs about once per month. Currently, the team stores everything in S3 Standard, and their monthly S3 bill is too high. They want to reduce storage cost without changing the requirement to keep logs for 180 days.

Which lifecycle approach best meets the goal?

Accepted Answer

Use a lifecycle policy to transition objects older than 30 days to S3 Standard-IA, and keep them there until day 180.. Option A is correct because it transitions logs older than 30 days to S3 Standard-IA, which offers lower storage costs than S3 Standard while still providing low-latency access for monthly reviews. The lifecycle policy keeps the objects in S3 Standard-IA until day 180, meeting the 180-day retention requirement without incurring the higher cost of S3 Standard for the entire period. S3 Standard-IA has a minimum storage duration of 30 days, which is satisfied by the 30-day transition threshold, and the objects remain immutable as S3 Object Lock is not affected by lifecycle transitions.

Answer

Use a lifecycle policy to transition objects older than 30 days to S3 Glacier Deep Archive and delete after 30 days.

Answer

Use a lifecycle policy to transition objects older than 30 days to S3 Intelligent-Tiering with no minimum storage duration.

Answer

Disable lifecycle management and instead lower costs by deleting objects immediately after they are written.

Question 14

A marketing team runs a report-generation process that must execute once per day at 02:00 UTC. It usually completes in 10315 minutes, but sometimes takes up to 45 minutes due to varying data volumes. They currently run the workload on an EC2 instance that is always on, which wastes money during off-hours. The team wants to minimize operational overhead and pay mainly for actual execution time.

What is the best architecture choice?

Accepted Answer

Use an EventBridge schedule to run the report as an Amazon ECS task on AWS Fargate and write results to S3.. Option B is correct because AWS Fargate allows the report-generation task to run as an Amazon ECS task triggered by an EventBridge schedule, eliminating the need for an always-on EC2 instance. Fargate charges only for the vCPU and memory resources consumed during the task's execution (typically 10–45 minutes), which aligns with the team's goal of minimizing operational overhead and paying mainly for actual execution time. Writing results to S3 provides durable, cost-effective storage without managing infrastructure.

Answer

Use a scheduled Amazon EC2 Auto Scaling group that keeps a minimum of one instance running at all times.

Answer

Use AWS Lambda triggered by an EventBridge schedule at 02:00 UTC and write results to S3.

Answer

Use an EMR cluster provisioned daily with manual teardown to ensure the instance is always available before 02:00.

Question 15

A startup runs two EC2-based workloads in the same AWS Region. Its customer-facing API is always on, and its nightly video transcoding fleet can restart jobs from checkpoints if an instance is interrupted. The finance team wants the lowest monthly compute cost without changing the application design. Which two actions should the team take? Select two.

Accepted Answer

Buy a Compute Savings Plan to cover the always-on API baseline usage.. Option B is correct because a Compute Savings Plan offers the lowest cost for steady-state workloads like the always-on API by committing to a consistent amount of compute usage (measured in $/hour) across any EC2 instance family, size, or region, providing up to 66% savings compared to On-Demand. Option C is correct because the transcoding fleet can tolerate interruptions (jobs restart from checkpoints), making Spot Instances ideal for up to 90% discount over On-Demand, which directly minimizes compute cost without architectural changes.

Answer

Purchase an All Upfront Reserved Instance for the transcoding fleet only.

Answer

Increase the API instance size so CPU utilization stays below 30 percent.

Answer

Move the API tier to Dedicated Hosts to improve isolation and lower spend.