SAA-C03 Design Resilient Architectures Practice Test 10 — 15 Questions

Question 1

A company runs a stateful analytics workload on EC2 instances that use EBS volumes. The data must be restorable in another Region after a major outage, with frequent point-in-time recovery. Which approach provides the most suitable replication mechanism for the EBS-backed data?

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

Accepted Answer

Create scheduled EBS snapshots and copy them to another Region, then restore the volumes from those snapshots during recovery.. Scheduled EBS snapshots provide point-in-time backups of EBS volumes, which can be copied to another Region using the cross-Region snapshot copy feature. During recovery, you restore volumes from those snapshots in the target Region, ensuring the data is restorable after a major outage. This approach meets the requirements for frequent point-in-time recovery and cross-Region durability.

Answer

Enable EBS multi-attach to spread the workload across AZs and replicate snapshots automatically between Regions.

Answer

Use RDS read replicas in another Region and keep the analytics dataset in an RDS instance only.

Answer

Rely on instance store for durability and copy only AMIs across Regions.

Question 2

An order processing workflow uses Amazon SQS as the decoupling layer between a producer and a consumer Lambda function. The consumer intermittently fails due to a downstream dependency. The team has observed that certain “poison” messages keep being retried repeatedly and prevent other messages from being processed efficiently. Which SQS configuration most directly addresses this issue?

Accepted Answer

Configure a redrive policy with a dead-letter queue (DLQ) and set an appropriate visibility timeout greater than the maximum processing time.. Configuring a redrive policy with a dead-letter queue (DLQ) allows messages that repeatedly fail processing to be moved out of the main queue after a specified number of receive attempts. Setting an appropriate visibility timeout greater than the maximum processing time ensures that messages are not made visible again before the consumer finishes processing, preventing premature retries. This directly isolates poison messages so they no longer block the processing of other messages in the queue.

Answer

Set the SQS queue’s retention period to 10 years and rely on application retries to eventually succeed.

Answer

Increase visibility timeout to a very large value and avoid dead-letter queues to keep ordering stable.

Answer

Switch the queue to FIFO and remove retries in the Lambda event source mapping entirely.

Question 3

A media company stores original uploads in an S3 bucket. They must recover from accidental overwrites/deletes and also recover quickly from a full Region outage. The required RPO is about 1 hour. Which configuration best meets these requirements?

Accepted Answer

Enable S3 versioning and configure cross-Region replication to a bucket in another Region.. Enabling S3 versioning protects against accidental overwrites and deletes by preserving all object versions, while cross-Region replication (CRR) asynchronously replicates objects to a bucket in another Region, providing recovery from a full Region outage. With versioning enabled, CRR replicates both current and previous object versions, meeting the ~1-hour RPO (typically within minutes for new objects) and ensuring data durability across Regions.

Answer

Enable an S3 lifecycle policy to transition objects to Glacier after 7 days without enabling versioning.

Answer

Enable S3 cross-Region replication (CRR) but leave the bucket without versioning enabled.

Answer

Rely on frequent EBS snapshots of a temporary cache used during uploads.

Question 4

An ECS service runs on EC2 instances and is fronted by an ALB. The ALB spans two Availability Zones, and the ECS service desired count is 2 tasks. The underlying EC2 capacity uses an Auto Scaling group (ASG) with min size set to 1, and the ASG also spans only one subnet in practice. What is the most effective change to meet the requirement that the service continues during a single-AZ instance loss?

Accepted Answer

Increase ASG min size to at least 2 and ensure the ASG uses subnets in at least two Availability Zones.. The current architecture has a single point of failure because the Auto Scaling group (ASG) spans only one subnet (one Availability Zone). If that AZ fails, all EC2 instances are lost, and the ECS service cannot run any tasks. Increasing the ASG min size to at least 2 and configuring it to use subnets in at least two AZs ensures that EC2 instances are distributed across AZs, allowing the ECS service to maintain at least one task in the surviving AZ during a single-AZ failure.

Answer

Set the ECS deployment configuration to maximum percent 100 so tasks replace instances faster during rollouts.

Answer

Enable ALB connection draining longer than expected so existing connections survive longer during an AZ event.

Answer

Reduce task memory reservations to pack both tasks onto a single EC2 instance.

Question 5

Your order-processing system uses EventBridge rules to send events to a Lambda function that updates order status. Over the last week, some events fail with a transient database timeout, and the Lambda retries intermittently but then the events are lost (no alerts after failures). You want at-least-once processing, bounded retries, and a way to inspect unprocessable events for later reprocessing.

Which architecture change best meets these requirements?

Accepted Answer

Send EventBridge events to an SQS queue, configure a redrive policy to move messages to a dead-letter queue (DLQ) after a defined receive count, and make the Lambda processing idempotent.. It introduces an SQS queue between EventBridge and Lambda, which provides a durable buffer for events. The redrive policy moves events to a dead-letter queue (DLQ) after a defined number of failed processing attempts, ensuring bounded retries and preserving unprocessable events for later inspection and reprocessing. Making the Lambda idempotent guarantees at-least-once processing even if duplicate events occur.

Answer

Invoke Lambda directly from EventBridge in asynchronous mode, and increase the Lambda timeout to reduce failures.

Answer

Use SNS topics with Lambda subscriptions, but remove all retry and DLQ configuration to minimize duplicate events.

Answer

Store failed events only in CloudWatch logs, and have operators manually copy log entries back into the database for reprocessing.

Question 6

A retail API runs on Amazon EC2 instances behind an Application Load Balancer and stores orders in an Amazon RDS for PostgreSQL database. A test that stopped one Availability Zone caused the API to return errors because all application servers were in the same AZ and the database was single-AZ. Which two changes should the architect make to continue serving traffic during a single-AZ failure? Select two.

Accepted Answer

Configure the Auto Scaling group to launch instances across private subnets in at least two Availability Zones.. Option B is correct because an Auto Scaling group that spans private subnets in at least two Availability Zones ensures application instances remain available if one AZ fails, and the ALB can route to healthy targets in the surviving AZ. Option D is correct because converting RDS for PostgreSQL to a Multi-AZ deployment creates a synchronous standby in a different AZ and automatically fails over the database endpoint, eliminating the single-AZ database as a point of failure. Option A is wrong because increasing instance size does not address the single-AZ placement of the application servers. Option C is wrong because a single-AZ Network Load Balancer still fails when that AZ fails and does not improve database resilience. Option E is wrong because a read replica is asynchronous, is not an automatic failover target for writes, and pointing the application at the replica endpoint does not provide a highly available primary database.

Answer

Increase the EC2 instance size and keep all application servers in the same subnet.

Answer

Replace the Application Load Balancer with a Network Load Balancer in a single Availability Zone.

Answer

Add an Amazon RDS read replica and point the application to the replica endpoint.

Question 7

An engineering team deploys a stateless web API on EC2 using an Auto Scaling group and an Application Load Balancer (ALB). During a recent test, they noticed that when one Availability Zone was unavailable, traffic failed until new instances were manually launched. Which change most directly improves automatic failover for the compute layer within a single Region?

Accepted Answer

Ensure the ALB and Auto Scaling group span multiple subnets in at least two Availability Zones.. An Application Load Balancer (ALB) and Auto Scaling group must span multiple subnets in at least two Availability Zones (AZs) to provide automatic failover. When one AZ becomes unavailable, the ALB automatically reroutes traffic to healthy targets in the remaining AZs, and the Auto Scaling group can launch replacement instances in the surviving AZs. This architecture ensures that the compute layer remains available without manual intervention.

Answer

Place the Auto Scaling group in only one subnet so instance launches are simpler.

Answer

Increase the target group deregistration delay to allow old instances to stay longer.

Answer

Use a Network Load Balancer, but keep all subnets in a single Availability Zone.

Question 8

A customer portal must recover from a regional outage within a few hours. The business wants lower ongoing cost than a fully active second Region and does not want to rebuild everything from scratch during the outage. Which two DR patterns best fit that goal? Select two.

Accepted Answer

Pilot light. Pilot light (B) is correct because it keeps a minimal, always-on core (for example replicated data and pre-provisioned but scaled-down compute) in the DR Region, so recovery only requires scaling up and starting the remaining resources rather than rebuilding everything from scratch, and its low baseline footprint keeps ongoing cost well below a fully active second Region. Warm standby (C) is correct because it runs a scaled-down but fully functional copy of the workload in the second Region, allowing it to be scaled up to production capacity within hours while still costing less than a fully active second Region. Backup and restore (A) is not the best fit because recovery means redeploying and rebuilding the entire environment from backups, which typically exceeds a few hours and requires substantial manual effort. Multi-site active-active (D) is excluded because running full production capacity in two Regions simultaneously is the most expensive option and contradicts the goal of lower ongoing cost. Single-AZ deployment (E) is not a cross-Region DR pattern at all and provides no protection against a regional outage.

Answer

Backup and restore

Answer

Multi-site active-active

Answer

Single-AZ deployment

Question 9

Your media processing pipeline writes original uploads to an S3 bucket and later generates derivative files. An operator accidentally deletes a subset of original uploads in production. You need to (1) restore the deleted objects with minimal data loss and (2) protect against both regional disasters and future operator mistakes. The company requires recovery even if objects are deleted and later overwritten.

What is the most effective change to meet these requirements?

Accepted Answer

Enable S3 versioning on the bucket and configure cross-Region replication so previous versions are available after regional loss and accidental deletion.. Enabling S3 Versioning preserves all object versions, including overwrites and deletions (which become delete markers), allowing you to restore deleted objects by removing the delete marker. Cross-Region Replication (CRR) replicates both current and previous versions to a secondary Region, protecting against regional disasters. Together, they ensure recovery even if objects are deleted and later overwritten, meeting all requirements.

Answer

Move all objects to S3 Glacier Instant Retrieval and apply a lifecycle policy to keep only the latest object copy.

Answer

Use S3 server-side encryption with KMS keys and rely on access logs to manually recover the deleted objects.

Answer

Enable S3 bucket policies that deny DeleteObject, but do not enable versioning or replication.

Question 10

A company runs its customer-facing web app on EC2 behind an Application Load Balancer. The database is Amazon RDS for PostgreSQL. The requirement is that if a single Availability Zone fails, the database must automatically fail over within the same AWS Region with minimal application changes. Which database setup best meets this requirement?

Accepted Answer

Deploy the RDS PostgreSQL instance as Multi-AZ with automatic failover enabled.. RDS Multi-AZ for PostgreSQL automatically provisions and maintains a synchronous standby replica in a different Availability Zone. If the primary AZ fails, Amazon RDS automatically fails over to the standby, typically within 60–120 seconds, with no changes required to the application's connection string (the DNS name remains the same). This meets the requirement for minimal application changes and automatic failover within the same Region.

Answer

Use an RDS single-AZ instance and periodically restore from automated backups if needed.

Answer

Create a read replica in a different AZ and use it only when the primary fails.

Answer

Use RDS with Multi-AZ disabled, but increase storage IOPS to prevent failover.

Question 11

A media company stores daily financial exports in Amazon S3. The files must be protected against accidental overwrite or deletion, and the business also wants a second copy in another Region for recovery after a regional outage. Which two actions should the architect take? Select two.

Accepted Answer

Enable bucket versioning on the S3 bucket.. Option A is correct because enabling S3 bucket versioning preserves every prior version of an object, so an accidental overwrite creates a new version and an accidental delete only adds a delete marker, allowing the original data to be restored rather than lost. Option D is correct because S3 Cross-Region Replication (CRR) automatically copies objects to a bucket in a second AWS Region, providing the required second copy for recovery from a regional outage; versioning must be enabled on both source and destination buckets for replication to work. Option B is not relevant because S3 Transfer Acceleration only speeds up uploads over long distances using edge locations, and does not protect data or create a second copy. Option C is not appropriate because lifecycle policies to Glacier change storage class and cost, not immutability, and do not provide cross-Region recovery. Option E is not relevant because S3 Block Public Access only prevents public exposure and does not protect against overwrite, deletion, or regional failure.

Answer

Turn on S3 Transfer Acceleration for the bucket.

Answer

Use only lifecycle policies to move objects to Glacier.

Answer

Enable S3 Block Public Access on the bucket.

Question 12

A serverless order-ingestion API writes directly to a database. During traffic spikes, the database occasionally throttles, Lambda retries create duplicate order records, and some requests time out. Which two changes best improve buffering and safe retry behavior? Select two.

Accepted Answer

Put an Amazon SQS queue between the API and the database-processing function.. Option B is correct because inserting an Amazon SQS queue between the API and the database-processing function decouples ingestion from database writes, allowing the queue to absorb traffic spikes and buffer requests while the consumer processes them at a rate the database can sustain, which directly addresses throttling and timeouts. Option D is correct because making the database write idempotent using a unique request token or order ID ensures that Lambda retries of the same message do not create duplicate order records, which is the standard safe-retry pattern for at-least-once delivery systems like SQS. Option A is not appropriate because increasing the Lambda timeout while continuing direct database writes does nothing to buffer spikes or prevent duplicate records, and longer timeouts can worsen throttling pressure. Option C is not appropriate because SNS is a pub/sub fan-out service, not a durable buffering queue, and immediate delivery to all subscribers does not provide the backpressure or retry buffering needed here. Option E is not appropriate because disabling retries sacrifices reliability and does not solve the underlying throttling or duplicate-write problem.

Answer

Increase the Lambda timeout and keep writing directly to the database.

Answer

Replace SQS with SNS so every request is delivered immediately to all subscribers.

Answer

Disable retries so failed writes are never duplicated.

Question 13

An order system receives events and uses a Lambda function to write each order into a database. During traffic spikes, the database sometimes throttles, and Lambda retries lead to occasional message loss in the event flow. The team wants buffering, automatic retries, and a way to isolate messages that repeatedly fail so they can be inspected later. What design change best meets this need?

Accepted Answer

Use Amazon SQS as a buffer between the event source and Lambda, with an SQS dead-letter queue (DLQ).. Amazon SQS acts as a durable buffer between the event source and Lambda, absorbing traffic spikes and decoupling the producer from the consumer. The SQS dead-letter queue (DLQ) automatically captures messages that exceed the configured maximum retries, allowing the team to inspect and reprocess them later without loss. This design provides the required buffering, automatic retries via the Lambda event source mapping, and isolation of repeatedly failing messages.

Answer

Send events directly from EventBridge to Lambda without any queue to simplify the flow.

Answer

Use SNS fan-out to multiple Lambda functions, but keep no retry logic and no DLQ.

Answer

Store events in an S3 bucket and trigger Lambda immediately after each upload, without using DLQs.

Question 14

A SaaS application is deployed in us-east-1 and us-west-2 behind separate ALBs. The business wants DNS to send new clients to the primary Region when it is healthy and automatically fail over to the secondary Region when the primary endpoint is unhealthy. Which two Route 53 settings are required? Select two.

Accepted Answer

Use a failover routing policy with a primary and secondary record.. A failover routing policy is correct because it allows you to designate one record as primary and another as secondary. Route 53 will route traffic to the primary record as long as it is healthy, and automatically fail over to the secondary record when the primary is unhealthy. This directly meets the requirement to send new clients to the primary region when healthy and fail over to the secondary region.

Answer

Use weighted routing with a 50/50 traffic split between both Regions.

Answer

Use latency-based routing so clients always choose the fastest Region.

Answer

Use a geolocation policy without health checks.

Question 15

A team uses an S3 bucket to store important customer-generated exports. They need protection against accidental overwrites and also want copies of the data in another AWS Region for disaster recovery. Which S3 configuration best satisfies both requirements?

Accepted Answer

Enable S3 versioning and configure Cross-Region Replication to a destination bucket in another Region.. Enabling S3 versioning protects against accidental overwrites by preserving all object versions, allowing recovery of previous versions. Configuring Cross-Region Replication (CRR) automatically replicates objects to a destination bucket in another AWS Region, providing disaster recovery by maintaining a copy of the data in a separate geographic location.

Answer

Enable S3 lifecycle policies to automatically move objects to Glacier after 30 days only.

Answer

Disable all versioning and rely on AWS Backup to restore objects from a scheduled backup window.

Answer

Enable S3 Block Public Access and SSE-S3 encryption, without using versioning or replication.