SAA-C03 Design High-Performing Architectures Practice Test 3 — 15 Questions

Question 1

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.. The CloudFront cache hit ratio for static assets is reduced when query strings and cookies are forwarded to the origin, because each unique combination creates a separate cache entry. By creating a custom cache policy that includes only the 'v' query string (used for versioning) and excludes cookies, CloudFront can cache a single object for all users regardless of other query parameters or cookie values, maximizing cache hits while still serving the same file.

Answer

Enable Origin Shield and keep the current cache behavior unchanged.

Answer

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

Answer

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

Question 2

A media platform serves global users through Amazon CloudFront and an S3 origin. Match each requirement on the left to the CloudFront configuration or behavior on the right.

Accepted Answer

Block users from a specific country: Geo Restriction. Geo restriction blocks countries; Lambda@Edge can inspect User-Agent for device; cache behaviors set caching rules; referer header prevents hotlinking; origin shield caches dynamic content; origin groups allow multiple origins per behavior.

Answer

Reduce origin load for dynamic content: Geo Restriction

Answer

Provide origin failover: Lambda@Edge

Question 3

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 versioned name changes, creating a new URL that forces a cache miss and fetches the fresh content. This directly increases the cache-hit ratio for static assets while ensuring clients never serve outdated files.

Answer

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

Answer

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

Answer

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

Question 4

A team runs a stateless web app on Amazon EC2 behind an Application Load Balancer. During traffic spikes, new EC2 instances take several minutes to finish bootstrapping before they can receive traffic. Which Auto Scaling configuration most directly reduces the time until additional capacity is available?

Accepted Answer

Use an Auto Scaling warm pool so pre-initialized instances are ready to enter service.. An Auto Scaling warm pool allows you to maintain a pool of pre-initialized instances that are fully bootstrapped and ready to enter service. When a scale-out event occurs, instances from the warm pool can be moved into the Auto Scaling group and start receiving traffic almost immediately, bypassing the several-minute bootstrapping delay.

Answer

Increase the ALB target group deregistration delay.

Answer

Reduce the Auto Scaling group minimum size to one instance.

Answer

Replace the Application Load Balancer with a Network Load Balancer.

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 logic.

Answer

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

Answer

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

Answer

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

Question 6

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?

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. Since the workload can tolerate data loss and the scratch data is reproducible, the ephemeral nature of instance store is acceptable, and it offers the best performance for temporary, high-throughput scratch space.

Answer

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

Answer

Amazon EFS for a shared file system between multiple instances.

Answer

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

Question 7

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 create a special CloudFront identity and attach a bucket policy that grants that identity s3:GetObject permissions. This ensures that only CloudFront can fetch objects from the S3 bucket, while direct access via the S3 endpoint is denied, preventing users from bypassing CloudFront.

Answer

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

Answer

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

Answer

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

Question 8

Based on the exhibit, what change best reduces Lambda cold-start impact for a predictable user-upload workflow?

Accepted Answer

Enable provisioned concurrency for the function.. Provisioned concurrency pre-warms a specified number of execution environments so that when a user upload triggers the Lambda function, there is no cold-start latency. This is the most direct way to eliminate initialization time for a predictable workload, as it keeps instances ready to handle requests immediately.

Answer

Set a reserved concurrency limit for the function to protect it from throttling.

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Increase the function timeout to give more time for initialization.

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Move the function to a larger memory setting only to eliminate all initialization time.

Question 9

Based on the exhibit, which Amazon EFS performance mode is the best fit for this workload?

Accepted Answer

Use General Purpose performance mode for low-latency access.. General Purpose performance mode is the best fit for this workload because it provides the lowest latency for file operations, which is critical for applications like content management, web serving, or home directories that require consistent, sub-millisecond metadata latency. Max I/O mode, in contrast, trades off latency for higher throughput and IOPS, making it unsuitable for latency-sensitive workloads.

Answer

Use Max I/O performance mode to optimize for the highest possible latency tolerance.

Answer

Use One Zone storage class to increase metadata speed.

Answer

Use Provisioned Throughput mode because it is the only performance mode available.

Question 10

Your application uses ElastiCache Redis as a cache for user profiles stored in DynamoDB. You must ensure that when a profile is updated, subsequent reads see the latest value quickly. Which cache strategy is generally the best fit for this requirement?

Accepted Answer

Use a cache-aside approach with TTL plus explicit invalidation after writes.. A cache-aside (lazy loading) strategy with TTL and explicit invalidation ensures that after a write to DynamoDB, the stale Redis entry is removed, forcing the next read to fetch the fresh profile from DynamoDB and repopulate the cache. This combination minimizes the window of stale reads while maintaining high read performance, which is critical for user profile caches where consistency matters.

Answer

Write to DynamoDB only, and never update or invalidate the Redis cache.

Answer

Cache only for reads, and do not fetch from DynamoDB when a key is missing.

Answer

Rely on eventual consistency of Redis replication to propagate updates to all nodes.

Question 11

A team runs a latency-sensitive service on EC2 and needs consistent, low-latency block storage for a database. The application requires predictable performance and should be fast for random reads/writes. Which EBS volume type is the best choice?

Accepted Answer

EBS gp3 (general purpose SSD). B is correct because gp3 is a general-purpose SSD volume that provides consistent, low-latency performance for random read/write operations, making it ideal for latency-sensitive database workloads. It offers a baseline of 3,000 IOPS and 125 MB/s throughput, with the ability to independently scale up to 16,000 IOPS and 1,000 MB/s, ensuring predictable performance without the burst-bucket limitations of gp2.

Answer

EBS st1 (throughput optimized HDD)

Answer

EBS sc1 (cold HDD)

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EBS magnetic (legacy magnetic)

Question 12

A customer-facing application has a relational data model and needs frequent complex queries (joins and aggregations), but it also experiences a significant read-heavy workload. Which design choice best improves read performance while keeping relational features?

Accepted Answer

Add read replicas to an RDS or Aurora cluster and keep the primary for writes.. Adding read replicas to an RDS or Aurora cluster offloads read traffic from the primary instance, improving read performance for complex queries (joins and aggregations) while preserving the relational data model. Aurora automatically scales read replicas and uses a shared storage volume, making this highly efficient for read-heavy workloads.

Answer

Use DynamoDB with a single partition key and avoid indexes to keep writes simple.

Answer

Store the data in S3 and query it directly from the application without a database.

Answer

Switch the database to DynamoDB but keep using the same relational SQL queries and joins.

Question 13

A web application uses an Amazon Aurora DB cluster for a read-heavy workload. The application team needs higher read throughput but cannot change the database schema. They want to avoid blocking writes and are willing to route read traffic separately. What is the most appropriate architecture change?

Accepted Answer

Create Aurora read replicas and route SELECT queries to an Aurora reader endpoint.. Creating Aurora read replicas and routing SELECT queries to the Aurora reader endpoint is the most appropriate architecture change because Aurora's reader endpoint distributes read traffic across up to 15 low-latency read replicas, providing higher aggregate read throughput without blocking writes. This approach requires no schema changes and allows the application to separate read and write traffic, directly addressing the read-heavy workload requirement.

Answer

Scale up the writer instance storage only; read capacity will automatically increase without using a reader endpoint.

Answer

Move the Aurora cluster to Multi-AZ deployment mode only; read scaling is handled automatically without replicas.

Answer

Replace the cluster with a single RDS instance because it offers consistent performance for both reads and writes.

Question 14

A team serves image files from S3 through CloudFront. During a performance review, they notice that CloudFront cache hit ratio is low and the S3 origin receives many repeated requests for the same images. Request URLs include a volatile query parameter called 'sessionId' that changes for each user, but the image content is identical regardless of 'sessionId'. What configuration change will most effectively increase cache hit ratio?

Accepted Answer

Update the CloudFront cache policy so that 'sessionId' is not included in the cache key (and only stable query parameters are used).. The low cache hit ratio is caused by the volatile 'sessionId' query parameter being included in the CloudFront cache key, which creates a unique cache entry for every user request even though the image content is identical. By updating the cache policy to exclude 'sessionId' from the cache key, CloudFront will treat all requests for the same image as the same cached object, dramatically increasing the cache hit ratio and reducing load on the S3 origin.

Answer

Enable origin request policy to forward all query strings to S3 so responses are always correct for every sessionId.

Answer

Set the CloudFront minimum TTL to 0 seconds so cached objects expire quickly and fetch fresh content more often.

Answer

Disable caching by using CloudFront managed caching disabled so that every request validates with the origin.

Question 15

A trading analytics system deploys 10 EC2 instances that exchange very frequent, low-latency messages over the network. The instances must be placed as close together as possible to minimize network hop count and inter-node jitter. Which deployment choice best matches this requirement?

Accepted Answer

Use a cluster placement group so the instances are placed close together to reduce latency and jitter.. A cluster placement group is designed for low-latency, high-throughput scenarios by placing all instances in a single Availability Zone within the same rack or logical cluster, minimizing network hop count and inter-node jitter. This directly meets the requirement for very frequent, low-latency messaging between 10 EC2 instances.

Answer

Use a spread placement group to distribute instances across multiple underlying hardware to improve overall availability.

Answer

Use no placement group and rely on the Auto Scaling group to balance instance placement automatically.

Answer

Use a partition placement group so each instance is assigned to separate failure domains for low variance.