SAA-C03 Design Resilient Architectures Practice Test 6 — 15 Questions

Question 1

A global application experiences frequent writes and must survive a full Regional outage with near-zero data loss. The product team also requires that users can continue to write during the incident using the closest Region. Which approach is most aligned with these requirements?

Accepted Answer

Use an active/active design with multi-Region data replication (for example, global tables for the write-heavy datastore) and route traffic to multiple Regions based on health and latency.. Option A is correct because an active/active design with multi-Region data replication, such as DynamoDB global tables, allows writes to occur in any Region and replicates data asynchronously across Regions with sub-second latency. This ensures near-zero data loss (RPO of seconds) and continuous write availability during a full Regional outage, while Route 53 latency-based routing directs users to the closest healthy Region.

Answer

Use warm standby with periodic backups of the primary write datastore every 24 hours.

Answer

Use pilot light where the secondary Region runs only infrastructure templates and starts data replication only after detecting failure.

Answer

Use a single-writer model in one Region and deploy read-only replicas in the other Region for continuity.

Question 2

Based on the exhibit, the database must fail over automatically if the primary Availability Zone goes down. Which solution should the architect choose?

Accepted Answer

Convert the database to a Multi-AZ RDS deployment.. Option B is correct because a Multi-AZ RDS deployment 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, without requiring manual intervention or changes to the application connection string.

Answer

Create a read replica in the same Availability Zone as the primary database.

Answer

Increase the backup retention period to 35 days.

Answer

Move the database to an EC2 instance with an attached EBS volume.

Question 3

A payments platform requires disaster recovery across Regions. Requirements: RPO of 15 minutes and RTO of about 1 hour. The business cannot afford full duplicate capacity in both Regions all the time, but the team wants automated readiness so failover is mostly operationally guided rather than a slow rebuild. Which DR strategy is the best fit?

Accepted Answer

Warm standby, keeping core infrastructure and a partially provisioned environment ready in the secondary Region with frequent data replication.. Warm standby is the best fit because it maintains a partially provisioned environment in the secondary Region with core infrastructure (e.g., a smaller EC2 instance fleet, a replicated database) and uses frequent data replication (e.g., Amazon RDS cross-Region replication or DynamoDB global tables) to achieve an RPO of 15 minutes. The RTO of about 1 hour is achievable by scaling up the standby environment and redirecting traffic, which is faster than a full rebuild but avoids the cost of full duplicate capacity. This balances the business constraint of not affording active/active with the need for automated readiness and guided failover.

Answer

Backup and restore only, relying on scheduled snapshots and manual restores during incidents.

Answer

Pilot light, keeping only minimal infrastructure in the secondary Region and starting full services after failover.

Answer

Active/active, routing production traffic to both Regions continuously and accepting dual-region complexity.

Question 4

A company uses Amazon RDS for a PostgreSQL database powering a customer-facing application. The application’s availability depends on fast database failover with minimal manual intervention. The RDS instance currently runs as a single-AZ deployment in one DB subnet group. Which change most directly meets the goal?

Accepted Answer

Enable Multi-AZ for the RDS DB instance so AWS manages a standby in another Availability Zone with automatic failover.. Enabling Multi-AZ for the RDS DB instance creates a synchronous standby replica in a different Availability Zone. AWS automatically handles failover to the standby with no manual intervention required, meeting the goal of fast database failover with minimal manual intervention.

Answer

Create a read replica in a different Availability Zone and configure the application to fail over manually.

Answer

Switch the database to use EBS snapshots more frequently and restore in case of failure.

Answer

Pin the DB to a specific instance type with higher CPU credits to prevent CPU-related disconnects.

Question 5

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.. Option B is correct because the current architecture has a single point of failure: the ASG spans only one subnet (one AZ), so if that AZ fails, all EC2 instances are lost, and the ECS service cannot run any tasks. By increasing the ASG min size to at least 2 and ensuring it uses subnets in at least two AZs, the ASG will maintain at least one healthy instance in each AZ, allowing the ECS service to survive a single-AZ outage. This aligns with the AWS Well-Architected Framework's principle of deploying across multiple AZs for high availability.

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 6

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.. Option C is correct because configuring a redrive policy with a dead-letter queue (DLQ) allows messages that exceed a specified maximum receive count to be moved to the DLQ, isolating poison messages. Setting the visibility timeout greater than the maximum processing time ensures the consumer has enough time to process each message before it becomes visible again, preventing premature retries. This directly addresses the issue of poison messages blocking the queue and degrading throughput.

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 7

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?

Accepted Answer

Create scheduled EBS snapshots and copy them to another Region, then restore the volumes from those snapshots during recovery.. Option A is correct because scheduled EBS snapshots provide point-in-time recovery and can be copied to another Region for cross-region disaster recovery. When a major outage occurs, you can restore EBS volumes from those snapshots in the target Region, meeting the requirement for frequent restorable backups. This approach is native to AWS, cost-effective, and supports the stateful analytics workload without architectural changes.

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 8

A caching layer uses Amazon ElastiCache for Redis in front of a stateless web service. The service must continue to read cached responses during maintenance events and should automatically fail over to another node if one AZ becomes impaired. Which design change best satisfies this requirement?

Accepted Answer

Configure an ElastiCache Redis replication group with automatic failover across multiple Availability Zones.. Option B is correct because an ElastiCache Redis replication group with automatic failover across multiple Availability Zones ensures that if the primary node or its AZ becomes impaired, a read-replica in another AZ is automatically promoted to primary. This allows the stateless web service to continue reading cached responses during maintenance events without interruption, as the failover is transparent to the application.

Answer

Deploy a single-node Redis cluster and rely on application-level retries when cache misses occur.

Answer

Move the cache into the VPC but keep it in one Availability Zone to reduce network latency.

Answer

Use a Memcached cluster and configure only client-side connection pooling without failover support.

Question 9

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.. Option C is correct because 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, enabling recovery from a full Region outage. With an RPO of about 1 hour, CRR meets this requirement as replication typically completes within minutes to a few hours, and versioning ensures point-in-time recovery of previous object states.

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 10

A team wants a web application to keep serving traffic if one Availability Zone fails. Match each architecture element to the resilience behavior it provides.

Question 11

A stateless web API runs on EC2 instances behind an Application Load Balancer (ALB). The Auto Scaling group (ASG) currently uses subnets from only one Availability Zone, even though the ALB spans two Availability Zones. During maintenance of that single AZ, the ALB remains up but clients see timeouts because there are no healthy targets. Which change most directly improves resilience against an AZ failure?

Accepted Answer

Update the ASG to launch instances across subnets in at least two Availability Zones and ensure ALB health checks target an application-ready path.. Option B is correct because it directly addresses the single point of failure: the ASG only launches instances in one AZ, so when that AZ fails, the ALB has no healthy targets to route traffic to, causing timeouts. By configuring the ASG to span at least two AZs, the ALB can distribute traffic to healthy instances in the remaining AZ during maintenance, ensuring high availability. The ALB health check must target an application-ready path (e.g., /health) to accurately detect instance health and avoid routing requests to impaired instances.

Answer

Keep the ASG in one subnet/AZ, but enable ALB stickiness to reduce session interruption.

Answer

Add a NAT gateway in the public subnets so instances can reach the internet during maintenance events.

Answer

Create a second ALB in the same Availability Zone and route traffic using DNS failover.

Question 12

A web app runs on an EC2 Auto Scaling group behind an Application Load Balancer (ALB). The ALB is configured with health checks and the ASG spans three subnets in three Availability Zones. During an AZ outage, monitoring shows the number of healthy instances drops sharply and never returns to the original capacity until the ASG is manually adjusted. What change most directly improves resilience so capacity returns automatically during an AZ failure?

Accepted Answer

Configure the ASG to use the ALB target-group health checks (ELB/target-group health) and ensure the ASG has at least two subnets in different Availability Zones that remain available for instance placement.. Option B is correct because configuring the ASG to use ALB target-group health checks (ELB health checks) ensures that the ASG replaces instances that fail the ALB's health checks, including those in an impaired AZ. By also ensuring the ASG has at least two subnets in different AZs that remain available, the ASG can launch replacement instances in the healthy AZs when one AZ fails, automatically restoring capacity without manual intervention.

Answer

Reduce the ASG desired capacity by 1 and rely on the ALB to route traffic to fewer instances during the outage.

Answer

Move the ALB to only one subnet so health checks and routing remain consistent during the outage.

Answer

Add an S3 event trigger to terminate unhealthy instances so the ASG can scale back out using its scheduled actions.

Question 13

Your public API is hosted in two regions. You want Route 53 to automatically send traffic to the secondary region when the primary region’s endpoint fails. The primary API health check is returning failure codes, but clients still reach the primary region for several minutes. Which Route 53 configuration most directly addresses this behavior?

Accepted Answer

Use Route 53 failover routing with a primary record and a secondary record, each associated with its own health check, so Route 53 answers with the healthy region.. Option B is correct because Route 53 failover routing with health checks on both primary and secondary records ensures that when the primary health check fails, Route 53 stops returning the primary record's IP and instead returns the secondary record's IP. This directly addresses the observed behavior where clients still reach the primary region for several minutes—likely because the primary record's health check was not configured or associated, or a simple routing policy was used without health check integration, causing stale DNS responses to be served until TTL expires.

Answer

Use a single Alias A record with simple routing and a short TTL so Route 53 quickly changes the IP address.

Answer

Use weighted routing to send a small percentage of traffic to the secondary region, increasing it manually when the primary fails.

Answer

Use latency routing only, letting Route 53 choose the lowest-latency region at query time, without health checks.

Question 14

An orders service publishes payment instructions to an Amazon SQS queue. After occasional processing timeouts, the downstream consumer sometimes processes the same instruction twice, resulting in duplicate payment attempts. The team currently uses an SQS Standard queue with a visibility timeout of 2 minutes and relies on the consumer to finish before the timeout expires. What approach best improves resilience against duplicate processing?

Accepted Answer

Make the consumer idempotent using the order ID as a deduplication key, and set the visibility timeout longer than the worst-case processing time.. Option B is correct because making the consumer idempotent using the order ID as a deduplication key ensures that even if the same message is processed multiple times, the downstream system will only apply the payment once. Setting the visibility timeout longer than the worst-case processing time prevents the message from becoming visible again before the consumer finishes, eliminating the root cause of duplicate processing in a Standard queue.

Answer

Decrease visibility timeout to 10 seconds so duplicates are less likely to occur.

Answer

Use an EventBridge rule with a fixed retry policy that only retries when the payload matches exactly.

Answer

Enable a dead-letter queue (DLQ) only, without changing the queue type or consumer logic.

Question 15

A developer accidentally deletes important rows in an RDS database. The mistake is discovered 45 minutes later. The database has automated backups enabled with a retention period of 7 days. What is the best way to restore the database to a point just before the deletion?

Accepted Answer

Use point-in-time restore (PITR) to restore the database to a specific timestamp before the deletion, based on automated backups.. Point-in-time restore (PITR) allows you to restore an RDS DB instance to any second within the automated backup retention period (here, 7 days). Since the deletion occurred 45 minutes ago, you can specify a timestamp just before the deletion, and RDS will replay the transaction logs to bring the database to that exact state. This is the most precise and efficient recovery method for accidental data modifications.

Answer

Restore the latest manual snapshot and then run SQL scripts to revert the deletion.

Answer

Promote an existing read replica to be the primary and then copy the missing rows from logs.

Answer

Recreate the instance using the most recent CloudWatch metric alarm snapshot of storage metrics.