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 development team wants to ensure that their application can continue serving traffic even if an entire AWS Availability Zone (AZ) becomes unavailable. The application runs on Amazon EC2 instances in an Auto Scaling group and uses an Application Load Balancer (ALB). Which configuration should the team implement to meet this requirement?
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 launch EC2 instances across multiple AZs, and ensure the ALB is enabled for cross-zone load balancing.
Option A is correct because deploying EC2 instances across multiple Availability Zones (AZs) ensures that if one AZ fails, the remaining AZs continue to serve traffic. Enabling cross-zone load balancing on the ALB distributes incoming requests evenly across all healthy instances in all AZs, preventing traffic from being sent only to instances in the same AZ as the client. This architecture meets the requirement for high availability and fault tolerance at the AZ level.
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 EC2 instances across multiple AZs, and ensure the ALB is enabled for cross-zone load balancing.
Why this is correct
Multiple AZs provide resilience against AZ failure; cross-zone load balancing distributes traffic evenly.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a launch template with multiple instance types to ensure diversity across the fleet.
Why it's wrong here
Instance type diversity does not address AZ failure.
✗
Use a single AZ but configure EC2 Auto Scaling to replace unhealthy instances automatically.
Why it's wrong here
This does not protect against AZ failure.
✗
Launch all EC2 instances in the same AZ to minimize latency, and configure the Auto Scaling group to maintain a minimum of two instances.
Why it's wrong here
All instances in one AZ remain vulnerable to AZ failure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse instance-level resilience (e.g., replacing unhealthy instances) with AZ-level resilience, or they think that multiple instances in a single AZ provide sufficient fault tolerance, ignoring the fact that an AZ failure takes down all instances in that AZ.
Detailed technical explanation
How to think about this question
Cross-zone load balancing is enabled by default for Application Load Balancers, but it is critical to verify this setting, especially for Network Load Balancers where it is disabled by default. When cross-zone load balancing is active, the ALB distributes traffic to instances in all AZs equally, regardless of the AZ of the client. In a multi-AZ Auto Scaling group, the group automatically distributes instances across the specified AZs, and the ALB health checks ensure traffic is only routed to healthy instances, providing seamless failover if an entire AZ becomes unavailable.
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: Configure the Auto Scaling group to launch EC2 instances across multiple AZs, and ensure the ALB is enabled for cross-zone load balancing. — Option A is correct because deploying EC2 instances across multiple Availability Zones (AZs) ensures that if one AZ fails, the remaining AZs continue to serve traffic. Enabling cross-zone load balancing on the ALB distributes incoming requests evenly across all healthy instances in all AZs, preventing traffic from being sent only to instances in the same AZ as the client. This architecture meets the requirement for high availability and fault tolerance at the AZ level.
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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Question Discussion
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