- A
Place the Auto Scaling group in only one subnet so instance launches are simpler.
Why wrong: Using only one subnet/AZ removes redundancy. An AZ outage would still take down capacity until manual action occurs.
- B
Ensure the ALB and Auto Scaling group span multiple subnets in at least two Availability Zones.
Spreading the ALB and Auto Scaling group across at least two AZs provides redundant capacity. If one AZ fails, the ALB continues routing to healthy targets in the other AZ.
- C
Increase the target group deregistration delay to allow old instances to stay longer.
Why wrong: Changing deregistration delay affects connection draining, not capacity placement across AZs. It doesn’t create additional resilient instances.
- D
Use a Network Load Balancer, but keep all subnets in a single Availability Zone.
Why wrong: Switching load balancer type doesn’t fix the root cause. If capacity is only in one AZ, failures will still impact the service.
SAA-C03 Design Resilient Architectures Practice Question
This SAA-C03 practice question tests your understanding of design resilient architectures. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. A key principle to apply: application Load Balancers (ALBs) distribute traffic across multiple Availability Zones.. 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.
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?
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
Ensure the ALB and Auto Scaling group span multiple subnets in at least two Availability Zones.
Option B is correct because placing both the ALB and the Auto Scaling group across multiple subnets in at least two Availability Zones ensures that if one AZ becomes unavailable, the ALB can route traffic to healthy instances in the remaining AZs, and the Auto Scaling group can automatically launch replacement instances in the other AZs. This directly provides automatic failover for the compute layer within a single Region without manual intervention.
Key principle: Application Load Balancers (ALBs) distribute traffic across multiple Availability Zones.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Place the Auto Scaling group in only one subnet so instance launches are simpler.
Why it's wrong here
Using only one subnet/AZ removes redundancy. An AZ outage would still take down capacity until manual action occurs.
- ✓
Ensure the ALB and Auto Scaling group span multiple subnets in at least two Availability Zones.
Why this is correct
Spreading the ALB and Auto Scaling group across at least two AZs provides redundant capacity. If one AZ fails, the ALB continues routing to healthy targets in the other AZ.
Related concept
Application Load Balancers (ALBs) distribute traffic across multiple Availability Zones.
- ✗
Increase the target group deregistration delay to allow old instances to stay longer.
Why it's wrong here
Changing deregistration delay affects connection draining, not capacity placement across AZs. It doesn’t create additional resilient instances.
- ✗
Use a Network Load Balancer, but keep all subnets in a single Availability Zone.
Why it's wrong here
Switching load balancer type doesn’t fix the root cause. If capacity is only in one AZ, failures will still impact the service.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think a single-AZ setup with a load balancer is sufficient for high availability, but without multi-AZ subnets for both the ALB and Auto Scaling group, the architecture remains vulnerable to AZ failure and requires manual recovery.
Detailed technical explanation
How to think about this question
Under the hood, an ALB is inherently regional and can route traffic to targets across multiple AZs, but it must be configured with subnets in at least two AZs to enable cross-zone load balancing. The Auto Scaling group must also be configured with multiple subnets (one per AZ) so that it can launch instances in any of the specified AZs; if one AZ fails, the group automatically scales in the remaining AZs to maintain capacity. This design leverages the AWS Regional resilience model, where the ALB health checks and Auto Scaling lifecycle hooks work together to detect failures and replace instances without manual intervention.
KKey Concepts to Remember
- Application Load Balancers (ALBs) distribute traffic across multiple Availability Zones.
- Auto Scaling groups can launch instances into subnets across multiple AZs.
- Spanning multiple AZs provides fault tolerance against single AZ outages.
- ALBs automatically route traffic away from unhealthy instances or unavailable AZs.
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
Application Load Balancers (ALBs) distribute traffic across multiple Availability Zones.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Review application Load Balancers (ALBs) distribute traffic across multiple Availability Zones., then practise related SAA-C03 questions on the same topic to reinforce the concept.
- →
Design Resilient Architectures — study guide chapter
Learn the concepts, then practise the questions
- →
Design Resilient Architectures practice questions
Targeted practice on this topic area only
- →
All SAA-C03 questions
1,040 questions across all exam domains
- →
SAA-C03 study guide
Full concept coverage aligned to exam objectives
- →
SAA-C03 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related SAA-C03 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Design Secure Architectures practice questions
Practise SAA-C03 questions linked to Design Secure Architectures.
Design Resilient Architectures practice questions
Practise SAA-C03 questions linked to Design Resilient Architectures.
Design High-Performing Architectures practice questions
Practise SAA-C03 questions linked to Design High-Performing Architectures.
Design Cost-Optimized Architectures practice questions
Practise SAA-C03 questions linked to Design Cost-Optimized Architectures.
SAA-C03 VPC practice questions
Practise SAA-C03 questions linked to SAA-C03 VPC.
SAA-C03 S3 lifecycle policy questions
Practise SAA-C03 questions linked to SAA-C03 S3 lifecycle policy questions.
SAA-C03 RDS Multi-AZ questions
Practise SAA-C03 questions linked to SAA-C03 RDS Multi-AZ questions.
SAA-C03 IAM policy practice questions
Practise SAA-C03 questions linked to SAA-C03 IAM policy.
SAA-C03 Route 53 failover questions
Practise SAA-C03 questions linked to SAA-C03 Route 53 failover questions.
SAA-C03 CloudFront practice questions
Practise SAA-C03 questions linked to SAA-C03 CloudFront.
SAA-C03 NAT gateway questions
Practise SAA-C03 questions linked to SAA-C03 NAT gateway questions.
SAA-C03 VPC endpoint questions
Practise SAA-C03 questions linked to SAA-C03 VPC endpoint questions.
Practice this exam
Start a free SAA-C03 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this SAA-C03 question test?
Design Resilient Architectures — This question tests Design Resilient Architectures — Application Load Balancers (ALBs) distribute traffic across multiple Availability Zones..
What is the correct answer to this question?
The correct answer is: Ensure the ALB and Auto Scaling group span multiple subnets in at least two Availability Zones. — Option B is correct because placing both the ALB and the Auto Scaling group across multiple subnets in at least two Availability Zones ensures that if one AZ becomes unavailable, the ALB can route traffic to healthy instances in the remaining AZs, and the Auto Scaling group can automatically launch replacement instances in the other AZs. This directly provides automatic failover for the compute layer within a single Region without manual intervention.
What should I do if I get this SAA-C03 question wrong?
Review application Load Balancers (ALBs) distribute traffic across multiple Availability Zones., then practise related SAA-C03 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Application Load Balancers (ALBs) distribute traffic across multiple Availability Zones.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Keep practising
More SAA-C03 practice questions
- A content publishing system uses Lambda functions that call an unreliable third-party API. Failed events must be retaine…
- A startup runs two EC2-based workloads in the same AWS Region. Its customer-facing API is always on, and its nightly vid…
- A warehouse integration service must use shared file storage across Linux EC2 instances in multiple Availability Zones.…
- A team runs a stateless web app on Amazon EC2 behind an Application Load Balancer. During traffic spikes, new EC2 instan…
- A service in private subnets downloads product images from Amazon S3 and stores job state in DynamoDB. A NAT Gateway is…
- A static site is hosted in Amazon S3 and delivered by CloudFront. After a frontend release, the same JavaScript bundles…
Last reviewed: Jun 11, 2026
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.