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 stateless web application on EC2 instances behind an Application Load Balancer. To improve resilience, which configuration should be used for the EC2 instances?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use multiple EC2 instances across two or more Availability Zones
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.
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 one EC2 instance with a larger instance type
Why it's wrong here
Does not improve availability.
✗
Use a single, large EC2 instance in one Availability Zone
Why it's wrong here
Single AZ is a single point of failure.
✗
Use multiple EC2 instances in one Availability Zone with health checks disabled
Why it's wrong here
Disabling health checks can route traffic to unhealthy instances.
✓
Use multiple EC2 instances across two or more Availability Zones
Why this is correct
Provides fault tolerance across AZs.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think scaling vertically (larger instance) or using multiple instances in a single AZ is sufficient, but the DOP-C02 exam specifically tests the requirement for multi-AZ deployment to achieve resilience against AZ failures.
Detailed technical explanation
How to think about this question
Under the hood, the ALB uses cross-zone load balancing to distribute traffic evenly across instances in all enabled AZs, and health checks (default: HTTP 200 on the configured path) determine instance eligibility. In a real-world scenario, if an AZ experiences an AWS service disruption, the ALB's DNS failover and health check mechanism automatically shift traffic to healthy instances in remaining AZs, achieving a Recovery Time Objective (RTO) of seconds to minutes without manual intervention.
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 multiple EC2 instances across two or more Availability Zones — 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.
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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