SAA-C03 Design High-Performing Architectures Practice Test 8 — 15 Questions

Question 1

A Lambda function behind an API needs consistent low latency. Traffic normally drops to near zero, then spikes several times per hour. During spikes, the p95 latency often spikes above 800 ms due to cold starts. The team wants to keep using Lambda (no containers) but minimize cold start impact during predictable spikes. What is the best AWS configuration to meet this goal?

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

Accepted Answer

Enable Lambda provisioned concurrency on a published function alias and set the minimum provisioned instances to the baseline expected during spikes.. Provisioned concurrency initializes a specified number of execution environments in advance, keeping them warm and ready to handle requests instantly. By setting the minimum provisioned instances to the baseline expected during spikes, the function avoids cold starts for those requests, ensuring p95 latency stays low even when traffic surges from near zero.

Answer

Increase the function memory size to the maximum and rely on the larger memory to eliminate cold starts.

Answer

Configure an ALB with target group health checks to keep Lambda warm by sending periodic requests.

Answer

Turn on AWS CloudTrail data events to monitor cold start frequency and tune the runtime accordingly.

Question 2

A media processing service runs ECS tasks in multiple Availability Zones. Each task must read and write the same shared filesystem with low latency because tasks stream intermediate artifacts to other tasks. The team currently mounts an EBS volume per task, and cross-AZ tasks frequently cannot see each other’s files. Which option best resolves the shared filesystem requirement while supporting high-performing access?

Accepted Answer

Use Amazon EFS with mount targets in each Availability Zone so all tasks mount a common NFS filesystem over the AWS network.. Amazon EFS provides a fully managed, shared NFS filesystem that can be mounted concurrently by ECS tasks across multiple Availability Zones with low latency. It supports POSIX file operations, making it ideal for streaming intermediate artifacts between tasks. EFS mount targets in each AZ ensure local access, meeting the requirement for high-performing shared storage.

Answer

Keep using EBS, but attach the same EBS volume to tasks in multiple Availability Zones using EBS multi-attach so all tasks share the filesystem.

Answer

Use Amazon S3 for the intermediate artifacts and rely on S3 event notifications to emulate POSIX file operations.

Answer

Switch to instance store on each task and use SQS messages between tasks to copy intermediate artifacts.

Question 3

An application uses DynamoDB to store order status. Reads happen extremely frequently for the same few keys (for example, the most recent orders), and the team wants lower read latency without changing the table’s partition key design. Which AWS service best fits this requirement?

Accepted Answer

Amazon DAX (DynamoDB Accelerator) to cache frequently read items. Amazon DAX (DynamoDB Accelerator) is an in-memory cache that sits between your application and DynamoDB, providing microsecond read latency for frequently accessed items. Because the workload involves extremely frequent reads of the same few keys (hot keys), DAX reduces the load on the DynamoDB table and delivers faster responses without requiring any changes to the partition key design.

Answer

Provision AWS WAF rules to reduce DynamoDB read latency caused by bots

Answer

Enable multi-region writes in DynamoDB Global Tables to speed up reads locally

Answer

Add more read capacity units to DynamoDB and avoid caching entirely

Question 4

Your team runs a tightly coupled distributed workload (for example, synchronous training nodes) across many EC2 instances placed within a single cluster environment. The instances need low-latency networking to reduce delays at synchronization barriers. Which EC2 placement strategy should you use to improve inter-node latency?

Accepted Answer

Create a placement group with the 'cluster' strategy to place instances close together and reduce network latency.. A cluster placement group is the correct choice because it groups instances in a single Availability Zone with low-latency, high-bandwidth networking, ideal for tightly coupled workloads like synchronous training nodes that require minimal delay at synchronization barriers. This strategy places instances physically close together within the same rack or cluster, reducing network round-trip time and maximizing throughput for inter-node communication.

Answer

Create a placement group with the 'spread' strategy to separate instances across underlying hardware for fault tolerance.

Answer

Use the default placement strategy and rely on Auto Scaling to keep instances from drifting to different locations.

Answer

Avoid placement groups and instead use Amazon S3 for inter-node messaging to minimize direct network traffic between instances.

Question 5

An order lookup API repeatedly reads the same few items from DynamoDB. The application can tolerate slightly stale data for a few seconds, and the team wants the lowest-latency design with minimal application changes. Which two changes should they make? Select two.

Accepted Answer

Put Amazon DynamoDB Accelerator (DAX) in front of the table.. Option A is correct because Amazon DynamoDB Accelerator (DAX) is a fully managed, in-memory cache for DynamoDB that delivers microsecond read latency for repeated access to the same items, and it requires minimal application changes since it is API-compatible with DynamoDB. Option B is correct because eventually consistent reads cost half as many read capacity units and typically have lower latency than strongly consistent reads, and the scenario explicitly states the application can tolerate slightly stale data for a few seconds. Option C is wrong because strongly consistent reads are slower and consume twice the read capacity of eventually consistent reads, so they do not provide faster results. Option D is wrong because increasing item size does not reduce the number of requests and actually increases the cost and latency of each read. Option E is wrong because replacing DynamoDB with EBS volumes on EC2 would require major application changes, lose DynamoDB's managed scalability, and not provide the low-latency cached reads the team wants.

Answer

Switch all access to strongly consistent reads for faster results.

Answer

Increase the item size so fewer requests are needed.

Answer

Replace the table with Amazon EBS volumes mounted on EC2 instances.

Question 6

A team needs to distribute TCP traffic (not HTTP) across multiple services. The services must see the original client source IP for auditing. Which AWS load balancer is the best fit?

Accepted Answer

Network Load Balancer (NLB) using TCP listeners. A Network Load Balancer (NLB) is the best fit because it operates at Layer 4 (TCP/UDP) and preserves the original client source IP address by default, which is required for auditing. It can distribute raw TCP traffic across multiple services without inspecting application-layer headers, making it ideal for non-HTTP TCP workloads.

Answer

Application Load Balancer (ALB) using HTTP/HTTPS listeners with host-based routing

Answer

Classic Load Balancer (CLB) configured for TCP health checks only

Answer

API Gateway with a VPC Link to forward raw TCP traffic

Question 7

Your team hosts versioned static assets (for example, /static/app-<buildHash>.js). Each build hash never changes, but you release new files on new URLs. To maximize cache hit rate and reduce origin load using CloudFront, what should you do when generating HTTP responses for these assets?

Accepted Answer

Set Cache-Control: public, max-age=31536000, immutable for the versioned assets. Setting `Cache-Control: public, max-age=31536000, immutable` tells CloudFront and browsers to cache the versioned asset for one year (31536000 seconds) and never revalidate, since the URL changes with each new build. The `immutable` directive (RFC 8246) signals that the content will never change on that URL, eliminating conditional revalidation requests and maximizing cache hits, which reduces origin load.

Answer

Set Cache-Control: no-cache so CloudFront always revalidates with the origin

Answer

Set Cache-Control: max-age=0 and rely on CloudFront to cache by default

Answer

Disable CloudFront caching and forward all headers and query strings to the origin

Question 8

A research team runs a latency-sensitive distributed training job on Amazon EC2. They deploy 80 identical nodes that exchange small messages frequently and need low network jitter. The job must run entirely within one Availability Zone. Which placement group strategy should a solutions architect use to maximize intra-cluster network performance?

Accepted Answer

Use a cluster placement group to keep all instances in close proximity within the same Availability Zone.. A cluster placement group is the correct choice because it places all 80 EC2 instances in close physical proximity within a single Availability Zone, ensuring low-latency, high-bandwidth network connections with minimal jitter. This placement group type is specifically designed for tightly coupled, latency-sensitive workloads like distributed training that require frequent, small message exchanges, as it leverages non-blocking, high-throughput networking between instances.

Answer

Use a spread placement group to distribute instances across distinct hardware to reduce jitter.

Answer

Use a partition placement group and place each node into its own partition for uniform latency.

Answer

Do not use a placement group; rely on the default EC2 scheduling to balance latency and availability.

Question 9

A game streaming service must use UDP for real-time gameplay traffic. For external firewall allowlisting, the service requires stable, static IP addresses. The TLS handshake must be handled end-to-end by the application servers (the load balancer must not terminate TLS). Which AWS load balancing option best fits these requirements?

Accepted Answer

Use a Network Load Balancer (NLB) with a UDP listener, configure the NLB to use Elastic IP addresses for static IPs, and use TCP listeners for TLS passthrough to the application servers.. A Network Load Balancer (NLB) supports UDP listeners, which are required for real-time gameplay traffic, and can be assigned Elastic IP addresses to provide stable, static IPs for firewall allowlisting. Additionally, NLB supports TCP listeners with TLS passthrough, meaning it forwards the encrypted traffic without terminating the TLS handshake, allowing the application servers to handle end-to-end encryption as required.

Answer

Use an Application Load Balancer (ALB) with UDP listeners and configure TLS passthrough.

Answer

Use Amazon API Gateway with a WebSocket API and keepalive pings to provide UDP-like low-latency delivery.

Answer

Use a Classic Load Balancer and multiplex UDP over TCP to meet the UDP and low-latency requirements.

Question 10

A company runs an Amazon RDS for PostgreSQL database. The application performs frequent OLTP writes, but it also has a separate dashboard that runs heavy SELECT queries and is slowing down overall database performance. The writes must remain on the primary. What is the best approach to improve performance for the dashboard?

Accepted Answer

Create an RDS read replica and route the dashboard’s read-only queries to the replica endpoint. Creating an RDS read replica allows you to offload the heavy SELECT queries from the primary database instance. The replica asynchronously replicates data from the primary using PostgreSQL's streaming replication, so the dashboard can query the replica without impacting the OLTP write performance on the primary. This directly addresses the requirement that writes remain on the primary while improving dashboard query performance.

Answer

Increase instance storage throughput limits and disable synchronous replication to speed up all queries

Answer

Replace RDS with Amazon S3 because dashboards require SQL result caching

Answer

Move the primary database to a different AWS Region to reduce network latency

Question 11

A startup runs an HTTP/2 API that also supports WebSocket connections. They need path-based routing to separate microservices (for example, /api/* to Service A and /metrics/* to Service B) and want TLS terminated at the load balancer. Which AWS option best meets these requirements while maintaining high request performance?

Accepted Answer

Use an Amazon ALB with HTTP/2 support, WebSocket upgrades enabled, and listener rules for host/path-based routing.. An Application Load Balancer (ALB) natively supports HTTP/2, WebSocket upgrades, and path-based routing via listener rules. It terminates TLS at the load balancer, offloading encryption from backend services, and maintains high performance for both HTTP/2 and WebSocket traffic. This makes ALB the correct choice for the startup's requirements.

Answer

Use an Amazon NLB and configure target groups with HTTP health checks and listener rules for path-based routing.

Answer

Use Amazon API Gateway with a single backend integration and rely on the client to route requests to different microservices.

Answer

Use Amazon CloudFront without an ALB, and route requests to microservices using only custom origin headers.

Question 12

A backend API uses an AWS Lambda function behind API Gateway. The first requests after every weekly deployment experience cold starts, causing p95 latency spikes for a few minutes. Which configuration most directly prevents those cold starts for the published version?

Accepted Answer

Use Lambda provisioned concurrency for the version via an alias. Provisioned concurrency initializes a specified number of Lambda execution environments ahead of time, so that when the published version is invoked via an alias, there are no cold starts. This directly addresses the latency spikes caused by cold starts after a deployment, as the function is kept warm and ready to handle requests immediately.

Answer

Increase the Lambda memory size only, without changing how Lambda is invoked

Answer

Enable dead-letter queues (DLQ) to retry failed cold starts

Answer

Attach a CloudFront distribution to cache API Gateway responses for 5 minutes

Question 13

A DynamoDB table uses this schema: partition key = customerId, sort key = timestamp. During a marketing campaign, one customer generates extremely high read traffic and the application sees ProvisionedThroughputExceeded errors even though the table’s total capacity is sufficient. What change most directly improves read distribution across partitions?

Accepted Answer

Add a salt component to the partition key by changing it to customerId#salt, where salt is derived from a hash of requestId so a single customer’s requests are spread across many partitions; keep the sort key as timestamp.. Adding a salt to the partition key (e.g., customerId#hash(requestId)) distributes the read-heavy customer's data across multiple physical partitions. This prevents a single hot partition from throttling requests, even when the table's total provisioned capacity is sufficient. DynamoDB's partition key determines the internal hash used for data placement, so increasing partition key cardinality directly improves read distribution.

Answer

Increase the table’s provisioned read capacity units while keeping partition key = customerId.

Answer

Remove the sort key and use timestamp as the partition key to increase cardinality.

Answer

Switch to on-demand capacity and rely on DynamoDB to automatically distribute reads across partitions.

Question 14

Based on the exhibit, what change should the team make to achieve the lowest possible network latency for the distributed workload?

Accepted Answer

Move the workload into a cluster placement group in one Availability Zone.. A cluster placement group provides the lowest possible network latency and highest throughput by placing all instances in a single Availability Zone with low-latency, non-blocking 10 Gbps or 25 Gbps network connectivity between them. This is ideal for tightly coupled, distributed workloads that require frequent inter-node communication, such as HPC or data analytics jobs.

Answer

Place the instances in a spread placement group across multiple Availability Zones.

Answer

Add an Application Load Balancer in front of the workers to reduce inter-node latency.

Answer

Increase the EC2 instance size while keeping the current multi-AZ layout.

Question 15

An Aurora PostgreSQL cluster is experiencing high read latency because 85% of traffic consists of read-only queries. The write workload must stay on the writer instance, and the team wants to offload reads without changing the application’s core query patterns. What is the best architectural option?

Accepted Answer

Add Aurora reader instances (read replicas) and route read queries to the reader endpoint while keeping writes on the writer endpoint.. Adding Aurora reader instances (read replicas) and routing read queries to the reader endpoint offloads read traffic from the writer instance without altering application query patterns. Aurora reader endpoints automatically distribute read-only connections across all replicas, reducing latency on the writer while keeping writes on the writer instance. This directly addresses the 85% read-heavy workload without requiring application changes.

Answer

Increase the writer instance size so it can handle more reads and writes simultaneously.

Answer

Enable Multi-AZ failover only and rely on the standby to serve reads in normal operation.

Answer

Move the read workload to ElastiCache Redis while keeping DynamoDB as the SQL data source.