Question 486 of 1,040
Design Resilient ArchitectureshardMultiple ChoiceObjective-mapped

SAA-C03 Design Resilient Architectures Practice Question

This SAA-C03 practice question tests your understanding of design resilient architectures. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Network Topology
$ aws autoscaling describe-auto-scaling-groupsauto-scaling-group-names orders-asg$ aws elbv2 describe-target-healthtarget-group-arn arn:aws:elasticloadbalancing:us-east-1:111122223333:targetgroup/orders-tg/abcd1234"AutoScalingGroups": ["AutoScalingGroupName": "orders-asg","DesiredCapacity": 4,"MinSize": 4,"MaxSize": 8,"AvailabilityZones": ["us-east-1a", "us-east-1b"],"HealthCheckType": "EC2","HealthCheckGracePeriod": 300,"TargetGroupARNs": ["arn:aws:elasticloadbalancing:us-east-1:111122223333:targetgroup/orders-tg/abcd1234"]TARGETSi-01e2a3b4: healthyi-02e3b4c5: healthyi-03f4c5d6: unhealthyi-04a5d6e7: unhealthyApplication health endpoint:2026-04-27T13:05:22Z GET /health -> 500EC2 status checks: passing

Based on the exhibit, the application tier is not replacing unhealthy instances even though the Auto Scaling group spans two Availability Zones. What change most directly improves automatic recovery when the application process fails?

Network Topology
$ aws autoscaling describe-auto-scaling-groupsauto-scaling-group-names orders-asg$ aws elbv2 describe-target-healthtarget-group-arn arn:aws:elasticloadbalancing:us-east-1:111122223333:targetgroup/orders-tg/abcd1234"AutoScalingGroups": ["AutoScalingGroupName": "orders-asg","DesiredCapacity": 4,"MinSize": 4,"MaxSize": 8,"AvailabilityZones": ["us-east-1a", "us-east-1b"],"HealthCheckType": "EC2","HealthCheckGracePeriod": 300,"TargetGroupARNs": ["arn:aws:elasticloadbalancing:us-east-1:111122223333:targetgroup/orders-tg/abcd1234"]TARGETSi-01e2a3b4: healthyi-02e3b4c5: healthyi-03f4c5d6: unhealthyi-04a5d6e7: unhealthyApplication health endpoint:2026-04-27T13:05:22Z GET /health -> 500EC2 status checks: passing

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Set the Auto Scaling group health check type to ELB so target group health determines replacement.

Option B is correct because setting the Auto Scaling group health check type to ELB allows the ASG to use the target group's health checks, which monitor application-level health (e.g., HTTP 200 responses). When the application process fails, the ELB marks the instance as unhealthy, and the ASG immediately terminates and replaces it. This directly addresses the issue of unhealthy instances not being replaced, as the default EC2 health check only verifies instance status (e.g., running vs. stopped), not application responsiveness.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Increase the ASG desired capacity so that extra instances absorb the failed ones.

    Why it's wrong here

    This adds capacity, but it does not make the group react to application-level failure faster or more accurately.

    When this WOULD be correct

    In a scenario where the ASG is correctly configured to replace unhealthy instances but the application needs to handle sudden traffic spikes without downtime, increasing desired capacity ensures enough healthy instances are always available to absorb load.

  • Set the Auto Scaling group health check type to ELB so target group health determines replacement.

    Why this is correct

    This makes Auto Scaling replace instances that fail the load balancer health check even when EC2 status checks still pass. The exhibit shows the application health endpoint returns 500 while EC2 checks remain passing, so EC2-only health checks miss the failure. ELB-based health checks align replacement with real application availability.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Replace the Application Load Balancer with a Network Load Balancer to improve failover speed.

    Why it's wrong here

    A Network Load Balancer changes the traffic layer, but it does not solve the instance-replacement problem shown in the exhibit.

    When this WOULD be correct

    When the requirement is to handle sudden traffic spikes with minimal latency and the application can tolerate connection-level health checks, or when the architecture needs to preserve the source IP address of clients.

  • Increase the HealthCheckGracePeriod to the maximum value so the instances have more time to stabilize.

    Why it's wrong here

    A longer grace period delays health evaluation after launch, but the unhealthy instances here are already running and returning 500 responses.

    When this WOULD be correct

    This option would be correct in a scenario where instances are being prematurely terminated because health checks begin before the application finishes booting, causing false positives. Increasing the grace period gives the application more time to become healthy.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The SAA-C03 exam frequently reuses these exact scenarios with slightly different constraints.

Set the Auto Scaling group health check type to ELB so target group health determines replacement.Correct answer

Why this is correct

This makes Auto Scaling replace instances that fail the load balancer health check even when EC2 status checks still pass. The exhibit shows the application health endpoint returns 500 while EC2 checks remain passing, so EC2-only health checks miss the failure. ELB-based health checks align replacement with real application availability.

Increase the ASG desired capacity so that extra instances absorb the failed ones.Wrong answer — click to see why

Why this is wrong here

Increasing desired capacity adds more instances but does not fix the health check configuration; the ASG still uses EC2 status checks, which may not detect application-level failures, so unhealthy instances are not replaced.

★ When this WOULD be the correct answer

In a scenario where the ASG is correctly configured to replace unhealthy instances but the application needs to handle sudden traffic spikes without downtime, increasing desired capacity ensures enough healthy instances are always available to absorb load.

Why candidates choose this

Candidates think that adding more instances provides redundancy, but they overlook that the core issue is the health check type not detecting application failures, so extra instances won't be triggered to replace unhealthy ones.

Replace the Application Load Balancer with a Network Load Balancer to improve failover speed.Wrong answer — click to see why

Why this is wrong here

The question is about replacing unhealthy instances based on application process failure, not about failover speed. An NLB does not provide application-level health checks, so it would not detect application process failures.

★ When this WOULD be the correct answer

When the requirement is to handle sudden traffic spikes with minimal latency and the application can tolerate connection-level health checks, or when the architecture needs to preserve the source IP address of clients.

Why candidates choose this

Candidates may think that an NLB's faster failover and lower latency would improve recovery, but they overlook that the issue is about detecting application-level health, which requires an ALB's HTTP health checks.

Increase the HealthCheckGracePeriod to the maximum value so the instances have more time to stabilize.Wrong answer — click to see why

Why this is wrong here

Increasing HealthCheckGracePeriod only delays the start of health checks, but does not fix the root cause: the ASG is using EC2 status checks (default) instead of ELB health checks, so it never detects application-level failures.

★ When this WOULD be the correct answer

This option would be correct in a scenario where instances are being prematurely terminated because health checks begin before the application finishes booting, causing false positives. Increasing the grace period gives the application more time to become healthy.

Why candidates choose this

Candidates may think that giving instances more time to stabilize will prevent unnecessary replacements, but they overlook that the ASG must first be configured to use ELB health checks to detect application failures at all.

Analysis generated from the official SAA-C03blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume the default EC2 health check is sufficient for application-level failures, but it only checks instance state (running/stopped), not the application process, so the ASG never triggers replacement for application crashes.

Trap categories for this question

  • Command / output trap

    A Network Load Balancer changes the traffic layer, but it does not solve the instance-replacement problem shown in the exhibit.

Detailed technical explanation

How to think about this question

The default EC2 health check for an Auto Scaling group only checks the instance's system status (e.g., reachability via EC2 status checks), not the application running inside it. By switching to ELB health checks, the ASG relies on the target group's health checks, which can be configured to probe a specific path (e.g., /health) at Layer 7, ensuring that only instances with a healthy application process are kept. This is critical in multi-AZ deployments where an instance may be running but its application is unresponsive, as the ELB health check will detect the failure and trigger replacement via the ASG lifecycle hooks.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.

Quick reference

Cloud Service Model Comparison

ModelYou ManageProvider ManagesExamples
IaaSOS, runtime, apps, dataHardware, hypervisor, networkingEC2, Azure VMs, GCP Compute Engine
PaaSApps and dataOS, runtime, middleware, hardwareElastic Beanstalk, Azure App Service
SaaSData and settings onlyEverything elseMicrosoft 365, Salesforce, Workday
FaaS / ServerlessFunction code onlyInfra, scaling, runtimeLambda, Azure Functions, Cloud Run
CaaSContainers and appsKubernetes, OS, hardwareEKS, AKS, GKE

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this SAA-C03 question test?

Design Resilient Architectures — This question tests Design Resilient Architectures — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Set the Auto Scaling group health check type to ELB so target group health determines replacement. — Option B is correct because setting the Auto Scaling group health check type to ELB allows the ASG to use the target group's health checks, which monitor application-level health (e.g., HTTP 200 responses). When the application process fails, the ELB marks the instance as unhealthy, and the ASG immediately terminates and replaces it. This directly addresses the issue of unhealthy instances not being replaced, as the default EC2 health check only verifies instance status (e.g., running vs. stopped), not application responsiveness.

What should I do if I get this SAA-C03 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 11, 2026

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This SAA-C03 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SAA-C03 exam.