SAA-C03 Design Cost-Optimized Architectures Practice Test 6 — 15 Questions

Question 1

A team stores application logs in Amazon CloudWatch Logs. They enabled long retention and detailed dashboards, resulting in higher-than-expected monthly spend. Compliance requires retaining logs for 90 days, but operations only needs aggregated views. Which change most directly reduces CloudWatch Logs cost while meeting the requirement?

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

Accepted Answer

Set the CloudWatch Logs log group retention period to 90 days for the relevant log groups.. Setting the CloudWatch Logs log group retention period to 90 days directly reduces storage costs by automatically expiring logs after the compliance-required duration. This eliminates the cost of storing logs beyond 90 days, which was the primary driver of the higher-than-expected spend, while still retaining the data for the mandated period and allowing aggregated views via dashboards.

Answer

Disable VPC flow logs so the applications stop producing logs automatically.

Answer

Increase the logging level to DEBUG to reduce the number of log events by batching them.

Answer

Turn off CloudWatch alarms so logs stop being ingested into CloudWatch Logs.

Question 2

A website serves versioned JavaScript and CSS files through CloudFront, but origin fetches are still high and the CloudFront bill increased. Developers confirm that URLs include a version in the filename (for example, app.1.4.2.js). What CloudFront behavior/configuration is most likely to reduce origin fetches and associated costs?

Accepted Answer

Set long cache headers (for example, Cache-Control: max-age and immutable) on those versioned assets so CloudFront caches them longer.. Setting long cache headers like `Cache-Control: max-age=31536000, immutable` on versioned assets tells CloudFront to cache these objects at edge locations for an extended period. Since the filename changes with each new version, CloudFront treats each version as a unique object and will not re-fetch the old version from the origin, dramatically reducing origin fetches and associated costs.

Answer

Disable compression to reduce CPU time spent at the edge and therefore reduce total cost.

Answer

Lower the cache policy TTLs so clients always get the newest assets quickly.

Answer

Remove version identifiers from filenames so CloudFront caches fewer unique objects.

Question 3

A SaaS company runs a production API on an EC2 Auto Scaling group with steady demand 24/7. The team uses multiple instance types over time (they switch types during tuning) but the overall compute hours are stable. They want a cost reduction without committing to a specific instance type or size. Which AWS pricing option best meets the requirement?

Accepted Answer

Purchase a Compute Savings Plan for the region and commit to a dollar-per-hour amount. B is correct because a Compute Savings Plan provides the flexibility to change instance types, sizes, and even compute services (e.g., EC2, Fargate, Lambda) within a region while still receiving discounted rates (up to 66% vs. on-demand). This matches the requirement of reducing costs without committing to a specific instance type or size, as the plan is based on a dollar-per-hour commitment rather than instance family or tenancy.

Answer

Buy EC2 Spot Instances for the Auto Scaling group to maximize savings

Answer

Purchase Reserved Instances that are limited to a single specific instance type in the Auto Scaling group

Answer

Use on-demand only, and rely on Auto Scaling to reduce cost during low utilization

Question 4

A team stores application logs in an S3 bucket. They keep logs for 18 months for compliance. Access patterns: logs are heavily accessed during the first 30 days, rarely accessed between days 31 and 180, and almost never accessed after day 180. They currently store everything in S3 Standard and want to reduce storage cost without violating the 18-month retention requirement. What should they implement?

Accepted Answer

Create an S3 lifecycle policy to transition logs to Standard-IA after 30 days and to Glacier Deep Archive after 180 days. An S3 lifecycle policy can automatically transition objects from S3 Standard to S3 Standard-IA after 30 days (matching the heavy-access period) and then to S3 Glacier Deep Archive after 180 days (matching the near-zero-access period). This minimizes storage costs while retaining logs for the required 18 months, as Glacier Deep Archive offers the lowest storage cost for long-term archival data.

Answer

Leave logs in S3 Standard for 18 months and add a tag for internal reporting

Answer

Immediately move all logs to Glacier Instant Retrieval and expire after 18 months

Answer

Enable versioning and rely on object lifecycle expiration to reduce costs; do not change storage classes

Question 5

A static marketing site is served through CloudFront from an S3 origin. After a product update, customers report a drop in CloudFront cache hit ratio and the CloudFront bill increases because the origin is receiving many more requests for the same JS/CSS assets. Asset URLs are versioned, but requests now include an Authorization header even though these assets are public. Which CloudFront change most directly improves the cache hit ratio for these assets?

Accepted Answer

Configure the CloudFront cache policy so Authorization is not included in the cache key, and use an origin request policy that does not forward Authorization to the S3 origin for this behavior. The drop in cache hit ratio is caused by the Authorization header being included in the cache key, which makes CloudFront treat each request as unique even when the asset URL is the same. By configuring the cache policy to exclude Authorization from the cache key and using an origin request policy that does not forward it to S3, CloudFront can serve cached responses for all users regardless of their Authorization header, restoring the cache hit ratio.

Answer

Increase the origin's max connections to handle more origin fetches

Answer

Set CloudFront minimum TTL to 0 seconds so caches expire faster and origin fetches start again

Answer

Disable CloudFront compression because Authorization headers are not cacheable when compression is enabled

Question 6

A company hosts application servers in private subnets. They must access Amazon S3 and read secrets from AWS Secrets Manager, but they want to avoid internet egress. They currently use a NAT gateway and see high NAT-related costs. What change most directly reduces cost while keeping traffic on the AWS network?

Accepted Answer

Create a Gateway VPC endpoint for S3 and an Interface VPC endpoint for Secrets Manager, then route requests via those endpoints instead of NAT. It replaces the NAT gateway with VPC endpoints, which are free of data processing charges and keep all traffic within the AWS network. A Gateway VPC endpoint for S3 uses prefix lists and route table entries to send S3 traffic directly over the AWS backbone, while an Interface VPC endpoint for Secrets Manager uses AWS PrivateLink to provide private connectivity without internet egress. This eliminates NAT gateway hourly and data processing costs, directly addressing the cost concern.

Answer

Keep the NAT gateway and reduce instance size to lower NAT throughput charges

Answer

Switch Secrets Manager to use S3 as a storage backend so both services can use the S3 endpoint only

Answer

Move the private subnets to public subnets and attach an Internet Gateway to eliminate NAT

Question 7

A team runs an EC2-based service and ships logs to Amazon CloudWatch Logs. They enabled long log retention and turned on detailed monitoring to improve troubleshooting. Their monthly CloudWatch costs have grown unexpectedly. Compliance requires that the logs remain available in CloudWatch Logs (for querying and audits) for 90 days, and alerts/alarms do not require detailed EC2 monitoring. What change best reduces cost while meeting requirements?

Accepted Answer

Set the CloudWatch Logs retention to 90 days and disable detailed EC2 monitoring (use standard monitoring) for the instances. Reduces costs by setting CloudWatch Logs retention to exactly 90 days (meeting compliance) and disabling detailed monitoring (which incurs per-minute metrics charges) in favor of standard 5-minute monitoring. This directly addresses the two main cost drivers—long retention and detailed EC2 monitoring—while preserving the required 90-day log availability for queries and audits.

Answer

Keep the current long retention and detailed monitoring; reduce the log volume by sampling 10% of events

Answer

Move all logs to S3 immediately and delete the CloudWatch log groups to reduce costs

Answer

Increase CloudWatch alarm thresholds to reduce the number of metric datapoints

Question 8

A batch analytics job runs for several hours each night and can be interrupted and restarted. Which EC2 purchasing option should minimize cost?

Accepted Answer

Spot Instances. Spot Instances are the correct choice because they offer significant cost savings (up to 90% compared to On-Demand) and are ideal for fault-tolerant, interruptible workloads like batch processing. Since the job can be interrupted and restarted, it can handle Spot Instance terminations gracefully, making this the most cost-effective option.

Answer

On-Demand Instances only

Answer

Dedicated Hosts

Answer

Provisioned IOPS volumes

Question 9

A production internal reporting portal 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. A Compute Savings Plan offers the lowest prices on EC2 usage (up to 66% off On-Demand) in exchange for a 1- or 3-year commitment, and it automatically applies to any EC2 instance family in any region, giving the flexibility the team needs. Since the workload runs continuously with predictable usage for three years, this plan is ideal for reducing costs while retaining the ability to change instance families if needed.

Answer

Spot Instances only

Answer

Dedicated Instances

Answer

S3 Intelligent-Tiering

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?

Accepted Answer

S3 lifecycle policy that transitions objects to lower-cost storage classes over time. An S3 Lifecycle policy automates the transition of objects from S3 Standard (for frequent access) to S3 Standard-IA (infrequent access) after 30 days, then to S3 Glacier Deep Archive (for long-term retention) after one year, minimizing storage costs while maintaining data accessibility as needed.

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 media processing workflow in private subnets downloads large amounts of data from S3 through a NAT gateway. NAT data processing charges are high. What should the architect use to reduce cost?

Accepted Answer

Gateway VPC endpoint for Amazon S3. A Gateway VPC endpoint for Amazon S3 allows instances in private subnets to access S3 directly via the AWS network without traversing a NAT gateway, eliminating NAT data processing charges. This is the most cost-effective solution because NAT gateway costs are incurred per GB of data processed, and using a gateway endpoint avoids those charges entirely.

Answer

S3 Object Lambda

Answer

AWS Shield Advanced

Answer

A larger NAT gateway

Question 12

A dev sandbox 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 (Option C) is ideal for unpredictable workloads with long idle periods and occasional spikes because it automatically scales to handle traffic without requiring any capacity planning. You pay only for the reads and writes you actually perform, eliminating the cost of idle provisioned capacity and the operational overhead of managing scaling.

Answer

Reserved capacity for maximum daily traffic

Answer

Provisioned capacity set for peak traffic

Answer

Global tables in every Region

Question 13

A log archive has old unattached EBS volumes and many stale snapshots. Which two actions reduce storage cost without affecting running instances?

Accepted Answer

Delete unattached EBS volumes after verifying they are no longer needed. Unattached EBS volumes incur storage costs even when not in use, as EBS pricing is based on provisioned capacity per GB-month. Deleting them after verifying they are no longer needed eliminates this cost without affecting running instances, since attached volumes are untouched. This directly addresses the question's requirement to reduce storage costs without impacting running workloads.

Answer

Stop all EC2 instances in the account

Answer

Disable CloudTrail logging

Question 14

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?

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 sacrificing performance.

Answer

Cross-Region data replication for all data

Answer

io2 Block Express volumes for all instances

Answer

Dedicated Hosts by default

Question 15

A batch analytics job 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?

Accepted Answer

Whether one NAT gateway per AZ is sufficient for the required private subnets. The question asks what the architect should review first. Using two NAT gateways per Availability Zone (AZ) when only one private subnet per AZ needs outbound internet access is likely over-provisioned and costly. The architect should first verify if a single NAT gateway per AZ can handle the traffic load, as NAT gateways are highly available within an AZ and can support up to 45 Gbps of bandwidth. This review directly addresses cost optimization without sacrificing functionality.

Answer

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

Answer

Disabling route tables

Answer

Moving all workloads to public subnets