SAA-C03 Design Cost-Optimized Architectures Practice Test 13 — 15 Questions

Question 1

A startup runs a 24/7 web tier on Amazon EC2 with a stable baseline of 8 instances and a nightly analytics batch job that can resume from checkpoints if interrupted. The company wants to minimize monthly compute cost without hurting the always-on web tier. Which two actions should it take? Select two.

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Buy a Compute Savings Plan for the steady web tier baseline.. A Compute Savings Plan offers the largest discount (up to 66%) in exchange for a 1- or 3-year hourly spend commitment, and it automatically applies to any EC2 instance family, size, or region. For the stable 8-instance web tier that runs 24/7, this plan provides significant cost savings while maintaining full flexibility to change instance types or even move to containers or Lambda, without affecting the always-on requirement.

Answer

Buy Standard Reserved Instances only for the nightly analytics batch job.

Answer

Move the entire workload to On-Demand Instances for maximum flexibility.

Answer

Use Dedicated Hosts for the batch job so the fleet is isolated.

Question 2

Based on the exhibit, the company stores application logs in Amazon S3 for 400 days. The logs are read heavily for the first 30 days, occasionally for the next 90 days, and very rarely after that. Retrieval after day 120 can take up to several hours, but the data must remain available until day 400. Which lifecycle policy is the most cost-effective fit?

Accepted Answer

Transition logs to S3 Standard-IA after 30 days, then to S3 Glacier Flexible Retrieval after 120 days, and expire them at 400 days.. It aligns the storage class transitions with the access patterns: S3 Standard for the first 30 days (heavy reads), S3 Standard-IA for the next 90 days (occasional reads), and S3 Glacier Flexible Retrieval for the remaining period (rare access, with retrieval up to several hours acceptable). This minimizes storage costs while ensuring data availability until day 400, where lifecycle expiration removes the objects.

Answer

Keep all logs in S3 Standard for 400 days and enable requester pays to reduce the company's bill.

Answer

Transition logs directly from S3 Standard to S3 Glacier Deep Archive after 30 days and expire them at 400 days.

Answer

Move logs to S3 Intelligent-Tiering only and disable lifecycle transitions because access is unpredictable.

Question 3

A media company runs a nightly batch job that processes video thumbnails. The batch can be interrupted at any time, and workers can resume automatically from checkpoints (a termination does not corrupt progress). The business goal is the lowest possible compute cost, and occasional interruptions are acceptable as long as the job continues automatically. Which approach is most cost-optimized?

Accepted Answer

Use EC2 Spot Instances and implement interruption handling with checkpoint-based restarts. Spot Instances offer the lowest compute cost (up to 90% discount vs. On-Demand) and the checkpoint-based design ensures that interruptions are handled gracefully without data loss. The job can resume automatically from the last checkpoint, making Spot Instances ideal for fault-tolerant, interruptible batch workloads.

Answer

Run the job on On-Demand EC2 instances to avoid interruptions

Answer

Buy Reserved Instances for the entire job window because interruptions are acceptable anyway

Answer

Use Savings Plans but schedule the job only during business hours to reduce the commit cost

Question 4

An Auto Scaling group for a background worker runs EC2 instances continuously. Over the last 30 days, CloudWatch shows sustained CPU utilization around 6% with no memory pressure, and queue processing latency meets all SLAs. The team wants to lower monthly cost with minimal risk. What is the best next action?

Accepted Answer

Perform right sizing by downsizing to a smaller instance family/size and validate SLAs. The current instance type is over-provisioned, as sustained CPU utilization is only 6% with no memory pressure and all SLAs are met. Right-sizing to a smaller instance family or size directly reduces compute cost while maintaining performance, making it the lowest-risk, cost-optimization action. This aligns with the AWS Well-Architected Framework's cost optimization pillar, which recommends matching instance capacity to actual workload requirements.

Answer

Increase the instance size to reduce CPU throttling risk

Answer

Switch the group to Spot Instances to reduce cost without changing instance sizing

Answer

Buy Reserved Instances with a long term commitment before making any sizing changes

Question 5

A risk simulation workload uses CloudWatch Logs heavily. Retaining all debug logs forever is increasing costs. What should be configured?

Accepted Answer

CloudWatch Logs retention policies per log group. CloudWatch Logs retention policies allow you to set per-log-group expiration rules (e.g., 30 days, 90 days) to automatically delete old log events, directly reducing storage costs for debug logs that are no longer needed. This is the most cost-effective and targeted solution for managing log lifecycle without affecting other monitoring or configuration services.

Answer

AWS Config aggregation

Answer

CloudWatch detailed monitoring on all instances

Answer

Route 53 health checks

Question 6

A production log archive runs continuously on EC2 with predictable usage for the next three years. The team wants a discount while retaining some instance-family flexibility. What should they buy?

Accepted Answer

Compute Savings Plan. The Compute Savings Plan (C) is correct because it offers a discount (up to 66%) in exchange for a commitment to a consistent amount of compute usage (measured in $/hour) for a 1- or 3-year term, while allowing flexibility to change instance families, sizes, OS, tenancy, and even regions within EC2, Fargate, and Lambda. This matches the requirement of predictable usage for three years with instance-family flexibility, unlike Reserved Instances which lock to a specific instance family.

Answer

S3 Intelligent-Tiering

Answer

Dedicated Instances

Answer

Spot Instances only

Question 7

A batch analytics job has unpredictable DynamoDB traffic with long idle periods and occasional spikes. Which capacity mode should minimize operational overhead and avoid paying for idle provisioned capacity?

Accepted Answer

DynamoDB on-demand capacity mode. DynamoDB on-demand capacity mode automatically scales to handle unpredictable traffic spikes and idle periods, charging only for the reads and writes you perform. This eliminates the need to provision capacity for peak traffic, avoiding costs during long idle periods and reducing operational overhead from capacity management.

Answer

Reserved capacity for maximum daily traffic

Answer

Provisioned capacity set for peak traffic

Answer

Global tables in every Region

Question 8

A log archive serves infrequently accessed user documents that must be available immediately when requested. Which S3 storage class is likely the best cost fit?

Accepted Answer

S3 Standard-IA or S3 One Zone-IA depending on resilience requirements. S3 Standard-IA or S3 One Zone-IA is the best cost fit because the workload involves infrequently accessed data that requires immediate retrieval (millisecond latency). Standard-IA offers lower storage cost than S3 Standard while maintaining high durability and low-latency access, and One Zone-IA provides even lower cost for data that can tolerate a single-AZ failure. Both classes meet the 'available immediately' requirement, unlike Glacier tiers which have retrieval delays.

Answer

Instance store volumes

Answer

S3 Standard for all objects

Answer

S3 Glacier Deep Archive

Question 9

A marketing site has EC2 instances that are oversized based on CPU, memory, and network utilisation. Which AWS service should identify rightsizing recommendations?

Accepted Answer

AWS Compute Optimizer. AWS Compute Optimizer analyzes historical utilization metrics (CPU, memory, network, and storage) from CloudWatch and uses machine learning to identify over-provisioned or under-provisioned EC2 instances. It generates actionable rightsizing recommendations, including instance type changes, to optimize cost and performance. This directly addresses the scenario of oversized EC2 instances.

Answer

AWS Shield

Answer

AWS DataSync

Answer

AWS Artifact

Question 10

A test environment stores logs in S3. Logs are queried for 30 days, rarely accessed for one year, and then retained for compliance. What should reduce storage cost? The design must avoid adding custom operational scripts.

Accepted Answer

S3 lifecycle policy that transitions objects to lower-cost storage classes over time. S3 lifecycle policies automate the transition of objects between storage classes based on age, allowing logs to move from S3 Standard (for frequent querying) to S3 Standard-IA or S3 One Zone-IA (for rare access), and eventually to S3 Glacier Deep Archive (for long-term compliance retention). This reduces storage cost without custom scripts, aligning with the requirement to avoid operational overhead.

Answer

Keep all logs in S3 Standard indefinitely

Answer

Move all logs immediately to S3 Glacier Deep Archive

Answer

Use EBS snapshots for the logs

Question 11

A marketing site runs on x86 EC2 instances and uses open-source software with no architecture-specific licensing restriction. What should be evaluated to reduce compute cost? The design must avoid adding custom operational scripts.

Accepted Answer

AWS Graviton-based instances after performance testing. AWS Graviton-based instances (ARM architecture) offer up to 40% better price-performance compared to comparable x86 instances for many workloads. Since the marketing site uses open-source software with no architecture-specific licensing restrictions, migrating to Graviton after performance testing can significantly reduce compute costs without requiring custom operational scripts, as the OS and software can be recompiled for ARM natively.

Answer

Cross-Region data replication for all data

Answer

io2 Block Express volumes for all instances

Answer

Dedicated Hosts by default

Question 12

A marketing site stores logs in S3. Logs are queried for 30 days, rarely accessed for one year, and then retained for compliance. What should reduce storage cost? The design must avoid adding custom operational scripts.

Accepted Answer

S3 lifecycle policy that transitions objects to lower-cost storage classes over time. S3 Lifecycle policies allow you to automatically transition objects from S3 Standard to lower-cost storage classes like S3 Standard-IA (Infrequent Access) after 30 days, then to S3 Glacier Deep Archive after one year, without custom scripts. This matches the access pattern: frequent queries for 30 days, rare access for a year, then long-term retention for compliance. The policy automates cost reduction by moving data to progressively cheaper storage as access frequency decreases.

Answer

Keep all logs in S3 Standard indefinitely

Answer

Use EBS snapshots for the logs

Answer

Move all logs immediately to S3 Glacier Deep Archive

Question 13

A internal reporting portal has old unattached EBS volumes and many stale snapshots. Which two actions reduce storage cost without affecting running instances? The design must avoid adding custom operational scripts.

Accepted Answer

Delete unattached EBS volumes after verifying they are no longer needed. Deleting unattached EBS volumes directly reduces storage costs without impacting running instances, as these volumes are not in use. Option D is correct because snapshot lifecycle policies automate the deletion of obsolete snapshots, eliminating manual cleanup and reducing storage costs without custom scripts.

Answer

Disable CloudTrail logging

Answer

Stop all EC2 instances in the account

Question 14

A test environment runs on x86 EC2 instances and uses open-source software with no architecture-specific licensing restriction. What should be evaluated to reduce compute cost? The design must avoid adding custom operational scripts.

Accepted Answer

AWS Graviton-based instances after performance testing. AWS Graviton-based instances (ARM architecture) offer up to 40% better price-performance compared to x86 instances for many workloads. Since the environment uses open-source software with no architecture-specific licensing restrictions, migrating to Graviton after performance testing can significantly reduce compute costs without requiring custom operational scripts, as AWS provides native support for ARM-based instances.

Answer

Cross-Region data replication for all data

Answer

io2 Block Express volumes for all instances

Answer

Dedicated Hosts by default

Question 15

A dev sandbox currently uses two NAT gateways in each of three Availability Zones, but only one private subnet per AZ needs outbound internet access. What should the architect review first? The design must avoid adding custom operational scripts.

Accepted Answer

Whether one NAT gateway per AZ is sufficient for the required private subnets. The question asks what the architect should review first to optimize costs while maintaining functionality. Using two NAT gateways per AZ when only one private subnet per AZ needs outbound internet access is redundant; a single NAT gateway per AZ can handle the traffic for all private subnets in that AZ. The design must avoid custom operational scripts, so the simplest review is to check if one NAT gateway per AZ is sufficient, which would reduce costs without breaking connectivity.

Answer

Disabling route tables

Answer

Replacing every NAT gateway with an internet gateway attached to private subnets

Answer

Moving all workloads to public subnets