DOP-C02 Resilient Cloud Solutions Practice Question
This DOP-C02 practice question tests your understanding of resilient cloud solutions. 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.
A company is designing a highly available architecture for a web application that uses Amazon EC2 instances. The application must be resilient to the failure of a single instance and a single Availability Zone. Which TWO actions should the company take? (Choose TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use an Auto Scaling group with a minimum of two instances spread across two Availability Zones.
Option A is correct because an Auto Scaling group with a minimum of two instances spread across two Availability Zones ensures that if one instance or one entire AZ fails, the remaining instance(s) in the other AZ can continue serving traffic, and Auto Scaling will automatically launch a replacement instance in the healthy AZ to restore the desired count. Option B is correct because distributing EC2 instances across at least two Availability Zones is the fundamental requirement for AZ-level resilience, as it eliminates a single point of failure at the AZ boundary.
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.
✓
Use an Auto Scaling group with a minimum of two instances spread across two Availability Zones.
Why this is correct
Auto Scaling group with multiple AZs provides automatic recovery and resilience.
Related concept
Read the scenario before looking for a memorised answer.
✓
Distribute EC2 instances across at least two Availability Zones.
Why this is correct
Multiple AZs provide resilience to an AZ failure.
Related concept
Read the scenario before looking for a memorised answer.
✗
Place all EC2 instances in a single Availability Zone and use a Network Load Balancer.
Why it's wrong here
Single AZ is not resilient.
✗
Use a single Application Load Balancer in one Availability Zone.
Why it's wrong here
The ALB should also be multi-AZ; a single AZ ALB is a single point of failure.
✗
Use a single large EC2 instance in one Availability Zone.
Why it's wrong here
A single instance is a single point of failure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think a load balancer alone provides high availability, but they overlook that the load balancer itself must be deployed across multiple AZs (or be a Regional service like ALB with cross-zone load balancing enabled) and that instances must be in at least two AZs to survive an AZ failure.
Detailed technical explanation
How to think about this question
Under the hood, an Auto Scaling group with a multi-AZ distribution leverages the AWS Regional service model where the Auto Scaling service itself is resilient across AZs; it uses health checks (EC2 status checks or ELB health checks) to detect instance failure and automatically triggers a replacement launch in a healthy AZ. A subtle behavior is that if an entire AZ becomes impaired, Auto Scaling will not launch new instances into that AZ until it is restored, instead distributing replacements across the remaining healthy AZs, which maintains capacity as long as at least one AZ is operational.
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
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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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: Use an Auto Scaling group with a minimum of two instances spread across two Availability Zones. — Option A is correct because an Auto Scaling group with a minimum of two instances spread across two Availability Zones ensures that if one instance or one entire AZ fails, the remaining instance(s) in the other AZ can continue serving traffic, and Auto Scaling will automatically launch a replacement instance in the healthy AZ to restore the desired count. Option B is correct because distributing EC2 instances across at least two Availability Zones is the fundamental requirement for AZ-level resilience, as it eliminates a single point of failure at the AZ boundary.
What should I do if I get this DOP-C02 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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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.
Question Discussion
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