SAA-C03 Design High-Performing Architectures Practice Test 12 — 15 Questions

Question 1

A compute workload uses temporary scratch space for intermediate results (reproducible), and it can tolerate data loss if the instance is terminated. The workload benefits from very high local I/O throughput. Which storage option is the best fit for the scratch data?

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

Accepted Answer

Instance store for local temporary files that can be lost when the instance stops.. Instance store volumes provide very high local I/O throughput because they are physically attached to the host server, making them ideal for temporary scratch data that is reproducible and can tolerate loss. Since the workload explicitly accepts data loss on instance termination and does not require persistence across reboots, instance store is the best fit for this use case.

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Amazon EBS General Purpose (gp3) volumes to persist intermediate results across reboots.

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Amazon EFS for a shared file system between multiple instances.

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Amazon S3 for scratch data so it is always durable and accessible from anywhere.

Question 2

Based on the exhibit, which change best reduces latency during peak traffic without overprovisioning the fleet?

Accepted Answer

Change the Auto Scaling policy to target tracking on ALB RequestCountPerTarget.. Using a target tracking scaling policy on ALB RequestCountPerTarget dynamically adjusts the fleet size based on the actual number of requests each instance receives. This ensures that during peak traffic, additional instances are added only when needed, reducing latency by distributing the load without overprovisioning. It directly addresses the goal of minimizing latency during spikes while maintaining cost efficiency.

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Replace the instances with a larger instance family so each server has more headroom.

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Use scheduled scaling to add instances only during the business hours peak window.

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Replace the ALB with a Network Load Balancer to reduce request latency.

Question 3

A media company uses CloudFront in front of an S3 bucket origin for video thumbnails. They want to prevent users from bypassing CloudFront and accessing the S3 bucket directly, while still allowing CloudFront to fetch objects. What is the best option?

Accepted Answer

Use CloudFront Origin Access Control (OAC) or Origin Access Identity (OAI) and update the bucket policy to allow only CloudFront.. CloudFront Origin Access Control (OAC) or Origin Access Identity (OAI) allows you to restrict direct access to an S3 bucket by configuring the bucket policy to grant read permissions only to the CloudFront distribution's service principal. This ensures that users can only retrieve thumbnails through CloudFront, leveraging its caching and security features, while blocking any direct S3 requests.

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Keep the bucket public and rely on signed cookies for all thumbnail requests.

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Enable S3 static website hosting so users access thumbnails directly from the S3 website endpoint.

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Set S3 bucket permissions to allow all IAM users and block access only by using a WAF rule at CloudFront.

Question 4

Based on the exhibit, which change will most improve the CloudFront cache hit ratio for the static assets while still serving the same files to all users?

Accepted Answer

Create a custom cache policy that includes only the v query string and excludes cookies.. Static assets (e.g., images, CSS, JS) are typically served identically to all users, so forwarding a unique query string like 'v' for versioning still allows CloudFront to cache a single object per version. By excluding cookies and other query strings, you prevent cache fragmentation caused by irrelevant variations, directly improving the cache hit ratio. This custom cache policy ensures that requests for the same 'v' value are served from the edge cache rather than forwarded to the origin.

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Enable Origin Shield and keep the current cache behavior unchanged.

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Move the static assets to individual presigned URLs for each viewer.

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Increase the CloudFront default TTL to 24 hours while continuing to forward all cookies and query strings.

Question 5

Based on the exhibit, which storage design best supports the application servers' shared working directory requirement?

Accepted Answer

Mount Amazon EFS on every EC2 instance and use it as the shared workspace.. Amazon EFS provides a fully managed, NFS-based shared file system that can be mounted concurrently on multiple EC2 instances across multiple Availability Zones. This directly satisfies the requirement for a shared working directory where all application servers can read and write files simultaneously without additional synchronization overhead.

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Attach one gp3 EBS volume to each instance and synchronize the files with cron jobs.

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Store the artifacts in S3 and have each node read them directly from S3 as a filesystem.

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Use instance store on each instance because it provides the fastest local file access.

Question 6

Based on the exhibit, which design change is the best way to reduce the observed read latency for this DynamoDB-backed service?

Accepted Answer

Add a DynamoDB Accelerator (DAX) cluster in front of the table and send repeated read traffic through it.. Adding a DynamoDB Accelerator (DAX) cluster in front of the table reduces read latency by providing an in-memory cache for repeated read traffic. DAX delivers microsecond response times for eventually consistent reads, which directly addresses the observed latency issue without requiring application-level caching or table redesign.

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Increase the on-demand table limits so DynamoDB can automatically absorb more traffic.

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Create a global secondary index on tenantId to distribute the load across more partitions.

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Move the dashboard data into S3 and use Lambda functions to read it on demand.

Question 7

A company serves mostly static images and JavaScript files from an origin in one AWS Region. They want to reduce origin load and improve global performance. Which change most directly increases cache-hit ratio for static assets while avoiding stale content?

Accepted Answer

Use versioned file names (e.g., app.abc123.js) and configure a long TTL with appropriate revalidation behavior.. Using versioned file names (e.g., app.abc123.js) allows you to set a long Cache-Control max-age TTL (e.g., one year) without risking stale content. When the file changes, the new version gets a new URL, so clients and edge caches immediately fetch the fresh object, maximizing cache hits for unchanged assets while avoiding stale content.

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Set Cache-Control headers on the origin to always be no-cache so clients revalidate frequently.

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Disable query string forwarding so all URLs without query strings share one cached object even when content differs.

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Forward all headers, including cookies, to maximize personalization in edge cached responses.

Question 8

A company runs a stateless web API on Amazon EC2 behind an Application Load Balancer. The team notices that during business hours, the ALB starts queueing requests and the average request latency rises. They want to scale out quickly and reliably based on demand, not CPU alone. Which Auto Scaling approach best matches this requirement?

Accepted Answer

Use target tracking scaling based on ALB request count per target.. Target tracking scaling based on ALB request count per target directly measures the load on each instance, allowing the Auto Scaling group to add or remove instances to maintain a target value. This approach scales out quickly and reliably based on actual demand (request queuing and latency), not just CPU, which aligns with the requirement to respond to rising latency and queueing during business hours.

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Use a fixed-size Auto Scaling group and increase capacity manually once per hour.

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Scale based only on EC2 instance memory utilization, regardless of load.

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Use step scaling with a single threshold on average network-in bytes.

Question 9

Based on the exhibit, which storage choice best matches the workload requirements?

Accepted Answer

Use instance store NVMe for the temporary processing workspace.. Instance store NVMe volumes provide temporary, ephemeral block storage directly attached to the EC2 instance, offering extremely low latency and high throughput for temporary processing workspaces. Since the workload requires a temporary workspace where data does not need to persist beyond the instance lifecycle, instance store is the optimal choice because it avoids the cost and overhead of durable storage while delivering the highest performance for scratch data.

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Use io2 EBS volumes because they provide the highest durable block storage performance.

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Use Amazon EFS for the workspace so the temporary files survive instance replacement.

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Use S3 as the working directory and read and write the intermediate files directly there.

Question 10

Based on the exhibit, which design change is the best way to reduce the observed read latency for this DynamoDB-backed service?

Accepted Answer

Add a DynamoDB Accelerator (DAX) cluster in front of the table and send repeated read traffic through it.. Adding a DynamoDB Accelerator (DAX) cluster in front of the table reduces read latency by providing an in-memory cache that serves repeated read requests with microsecond response times, bypassing the need to read from the underlying DynamoDB table's SSD storage. This directly addresses the observed latency issue for frequently accessed data, as DAX is optimized for read-heavy workloads and supports eventual and strong consistency reads.

Answer

Increase the on-demand table limits so DynamoDB can automatically absorb more traffic.

Answer

Create a global secondary index on tenantId to distribute the load across more partitions.

Answer

Move the dashboard data into S3 and use Lambda functions to read it on demand.

Question 11

A retail analytics app uses Amazon RDS for PostgreSQL. Read traffic is growing, and the database CPU spikes mainly due to SELECT-heavy workloads. Writes are less frequent, and the app can tolerate eventually consistent reads for the reports. What is the most appropriate AWS-native way to improve read performance with minimal application changes?

Accepted Answer

Create an RDS read replica and point the reporting queries to the replica endpoint.. Creating an RDS read replica is the most appropriate AWS-native solution because it offloads SELECT-heavy read traffic from the primary database instance to a separate read-only replica, reducing CPU spikes on the primary. The application can tolerate eventually consistent reads for reports, which aligns with the natural replication lag of RDS read replicas (typically sub-second). This requires minimal application changes—only updating the reporting queries to point to the replica endpoint—and leverages PostgreSQL's built-in streaming replication.

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Switch the cluster to DynamoDB without redesigning the data model.

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Enable S3 event notifications to trigger a Lambda function after each write to the database.

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Replace the RDS instance class with a smaller size to reduce cost and improve performance.

Question 12

Based on the exhibit, what is the best change to improve read performance without increasing write latency on the primary database?

Accepted Answer

Create an RDS read replica and direct the reporting queries to the replica endpoint.. Creating an RDS read replica offloads read-heavy reporting queries from the primary database instance, improving read performance without adding any write latency to the primary. The replica operates asynchronously, so writes on the primary are not blocked or delayed by the replica's lag. This is the standard AWS solution for scaling read traffic on RDS.

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Convert the DB instance to Multi-AZ so the primary can serve more reads.

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Increase the primary instance class to a larger size and keep all traffic on one writer.

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Migrate the reporting workload to DynamoDB to gain faster reads.

Question 13

Based on the exhibit, the team wants to improve application performance without changing the code. Which EC2 instance family should they choose next?

Accepted Answer

Choose a memory-optimized instance family such as R6i to provide more RAM.. The exhibit shows that the application is experiencing high memory utilization (e.g., memory pressure or swapping), which degrades performance. Choosing a memory-optimized instance family such as R6i provides more RAM per vCPU, directly addressing the bottleneck without requiring code changes. This improves application performance by reducing or eliminating swap usage and allowing more data to be cached in memory.

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Choose a compute-optimized instance family such as C6i to increase CPU performance.

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Choose a storage-optimized instance family such as I4i to improve block storage throughput.

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Choose a burstable instance family such as T3 to reduce cost and improve performance.

Question 14

A system uses multiple AWS Lambda functions behind different event sources. One Lambda occasionally spikes and causes other Lambdas to be throttled due to shared concurrency limits. Which setting best helps ensure the important Lambda keeps capacity during spikes?

Accepted Answer

Set Reserved Concurrency for the important Lambda function.. Reserved Concurrency guarantees that the important Lambda function always has a set number of concurrent executions available, preventing other functions from consuming the account-level concurrency pool and throttling it during spikes. This setting isolates the function's capacity from shared contention, ensuring its performance remains stable.

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Increase the function timeout so throttling is less likely.

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Enable Provisioned Concurrency for every Lambda in the account.

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Reduce the number of IAM policies attached to the Lambda roles.

Question 15

A web service runs on an Auto Scaling group (ASG). The team updates configuration (AMIs, environment variables) in a Launch Template and wants new instances created during scale-out to use the latest Launch Template version. What should the architect do?

Accepted Answer

Set the ASG to use the latest Launch Template version and optionally start an instance refresh for existing instances.. The Auto Scaling group can be configured to use the latest version of a launch template by specifying the `$Latest` version. This ensures that any new instances launched during scale-out automatically use the most recent configuration. Additionally, an instance refresh can be initiated to update existing instances to the latest template version without manual intervention.

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Leave the ASG attached to the previous Launch Template version so scale-out is stable.

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Manually SSH into each new instance and reconfigure it after it launches.

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Move the configuration changes into a security group rule so the ASG updates them automatically.