The answer is to configure the Auto Scaling group to span at least three Availability Zones and set the Application Load Balancer to route traffic to all AZs. This is the most resilient configuration because distributing EC2 instances across multiple AZs eliminates a single point of failure; if one AZ goes down, the remaining two zones absorb the full traffic load, ensuring continuous availability. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of high-availability architecture patterns, often appearing in questions about fault tolerance and disaster recovery. A common trap is assuming two AZs are sufficient, but AWS recommends three for production workloads to maintain capacity during a zone failure without overloading the surviving zones. Remember the memory tip: “Three is key for AZ resiliency—two leaves you vulnerable, three keeps you steady.”
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 runs a critical e-commerce application on Amazon EC2 instances behind an Application Load Balancer (ALB) with Auto Scaling. The application must be resilient to an Availability Zone (AZ) failure. What is the MOST resilient configuration?
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 at least three AZs and set the ALB to route traffic to all AZs.
Distributing instances across three AZs ensures that if one AZ fails, the remaining AZs can handle the load. This provides high availability and 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 launch instances in a single AZ with a larger instance type.
Why it's wrong here
Single AZ is not resilient to AZ failure.
✗
Deploy a single large EC2 instance in one AZ and use an Elastic IP for failover.
Why it's wrong here
Single instance is a single point of failure.
✗
Use a Network Load Balancer instead of an ALB and deploy instances in two AZs.
Why it's wrong here
Two AZs provide less resilience than three, and NLB does not add resilience by itself.
✓
Configure the Auto Scaling group to span at least three AZs and set the ALB to route traffic to all AZs.
Why this is correct
Multi-AZ deployment ensures resilience.
Related concept
Read the scenario before looking for a memorised answer.
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 at least three AZs and set the ALB to route traffic to all AZs. — Distributing instances across three AZs ensures that if one AZ fails, the remaining AZs can handle the load. This provides high availability and 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.
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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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