The correct answer is to configure the Auto Scaling group to span multiple Availability Zones and enable health checks to replace unhealthy instances. This approach ensures high availability by distributing instances across AZs, so when one AZ fails, the Auto Scaling group can launch new instances in the remaining healthy zones, while health checks automatically detect and replace failed instances to maintain capacity. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this concept tests your understanding of resilient architecture patterns, often appearing in questions that contrast horizontal scaling with vertical scaling or single-AZ pitfalls. A common trap is choosing to increase instance size or use a larger AMI, which does not address AZ-level failure. Memory tip: think “spread and replace”—spread instances across AZs and replace them via health checks to survive zone outages.
DOP-C02 Resilient Cloud Solutions Practice Question
This DOP-C02 practice question tests your understanding of resilient cloud solutions. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
A company runs a critical web application on EC2 instances behind an Application Load Balancer (ALB) across multiple Availability Zones. During a recent failure of one AZ, the application experienced downtime because the Auto Scaling group did not launch new instances quickly enough. What should a DevOps engineer do to improve resilience?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure the Auto Scaling group to span multiple AZs and enable health checks to replace unhealthy instances.
Option D is correct because distributing instances across multiple AZs ensures that failure of one AZ does not affect the entire application, and using a multi-AZ deployment with proper Auto Scaling group configuration is a best practice for high availability. Option A is wrong because increasing instance size does not mitigate AZ failure. Option B is wrong because a single AZ still presents a single point of failure. Option C is wrong because using a larger AMI does not help with resilience.
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.
✓
Configure the Auto Scaling group to span multiple AZs and enable health checks to replace unhealthy instances.
Why this is correct
Multiple AZs provide high availability and health checks ensure quick replacement.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a larger AMI to reduce boot times.
Why it's wrong here
Boot time reduction does not solve the AZ failure issue.
✗
Increase the instance size of the EC2 instances to handle more traffic.
Why it's wrong here
Instance size impacts performance, not resilience to AZ failure.
✗
Configure the Auto Scaling group to launch instances in a single AZ with a larger instance count.
Why it's wrong here
A single AZ is a single point of failure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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
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.
Identify which DOP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Resilient Cloud Solutions — This question tests Resilient Cloud Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure the Auto Scaling group to span multiple AZs and enable health checks to replace unhealthy instances. — Option D is correct because distributing instances across multiple AZs ensures that failure of one AZ does not affect the entire application, and using a multi-AZ deployment with proper Auto Scaling group configuration is a best practice for high availability. Option A is wrong because increasing instance size does not mitigate AZ failure. Option B is wrong because a single AZ still presents a single point of failure. Option C is wrong because using a larger AMI does not help with resilience.
What should I do if I get this DOP-C02 question wrong?
Identify which DOP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company runs a critical web application on EC2 instances behind an Application Load Balancer. To improve resilience, they want to automatically replace unhealthy instances. Which AWS feature should they use?
easy
✓ A.Auto Scaling group with ELB health checks
B.CloudWatch alarm that terminates the instance
C.AWS Lambda function that checks health and launches new instances
D.Elastic Load Balancer health checks
Why A: Auto Scaling groups with health checks automatically replace unhealthy instances. Option A is wrong because ELB health checks only mark instances unhealthy; replacement requires Auto Scaling. Option C is wrong because CloudWatch alarms trigger actions but not instance replacement. Option D is wrong because Lambda can invoke API calls but is not the native mechanism.
Variation 2. A company runs a critical web application on EC2 instances behind an Application Load Balancer. To improve resilience, they want to automatically replace failed instances. Which AWS service should they use?
medium
A.EC2 Instance Recovery
B.AWS Systems Manager Automation
C.CloudFormation Stack update
✓ D.Auto Scaling group with health checks
Why D: Auto Scaling automatically replaces unhealthy instances. ELB health checks integration triggers replacement. Option A is wrong because EC2 Instance Recovery only recovers on the same host. Option C is wrong because CloudFormation doesn't auto-replace. Option D is wrong because Systems Manager doesn't replace instances.
Variation 3. A company runs a stateless web application on EC2 instances behind an Application Load Balancer. To improve resilience, which configuration should be used for the EC2 instances?
easy
A.Use one EC2 instance with a larger instance type
B.Use a single, large EC2 instance in one Availability Zone
C.Use multiple EC2 instances in one Availability Zone with health checks disabled
✓ D.Use multiple EC2 instances across two or more Availability Zones
Why D: D is correct because deploying multiple EC2 instances across two or more Availability Zones (AZs) ensures high availability and fault tolerance. If one AZ fails, the Application Load Balancer (ALB) automatically routes traffic to healthy instances in other AZs, maintaining service continuity. This aligns with the AWS Well-Architected Framework's resilience best practices for stateless applications.
Last reviewed: Jun 20, 2026
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This DOP-C02 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 DOP-C02 exam.
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