The correct answer is to enable cross-zone load balancing on the Application Load Balancer. By default, an ALB distributes incoming traffic evenly across each Availability Zone, but within each zone, traffic is then spread only among the instances in that zone. Enabling cross-zone load balancing overrides this behavior, allowing the ALB to distribute traffic evenly across all healthy instances regardless of which Availability Zone they reside in, which is essential for achieving true even traffic distribution when instance counts vary between zones. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this concept tests your understanding of how ALB routing modes differ from the Network Load Balancer, which has cross-zone load balancing enabled by default. A common trap is assuming that the ALB’s default zonal distribution already balances across all instances, but it only balances across zones, not across individual instances within them. Memory tip: think of cross-zone as “crossing the zone boundary” to reach every instance equally.
DOP-C02 Resilient Cloud Solutions Practice Question
This DOP-C02 practice question tests your understanding of resilient cloud solutions. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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. The application runs on Amazon EC2 instances in an Auto Scaling group across three Availability Zones. The instances are behind an Application Load Balancer (ALB). Which additional step should the team take to ensure that traffic is evenly distributed across all healthy instances in all Availability Zones?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable cross-zone load balancing on the ALB.
Option C is correct. By default, ALB distributes traffic evenly across AZs, but cross-zone load balancing must be enabled to distribute traffic evenly across all instances regardless of AZ. Option A is wrong because ALB already distributes traffic across AZs. Option B is wrong because Route 53 is not needed for internal distribution. Option D is wrong because target group health checks are already enabled.
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 Amazon Route 53 weighted routing policy to distribute traffic to each AZ.
Why it's wrong here
Route 53 distributes traffic to the ALB, not within it.
✗
Configure health checks on the target group to mark instances as unhealthy if they are in an AZ with fewer instances.
Why it's wrong here
Health checks are based on instance health, not AZ distribution.
✓
Enable cross-zone load balancing on the ALB.
Why this is correct
This ensures even distribution across all instances in all AZs.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure the ALB to use least outstanding requests routing algorithm.
Why it's wrong here
This is a routing algorithm, but cross-zone balancing is still needed.
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: Enable cross-zone load balancing on the ALB. — Option C is correct. By default, ALB distributes traffic evenly across AZs, but cross-zone load balancing must be enabled to distribute traffic evenly across all instances regardless of AZ. Option A is wrong because ALB already distributes traffic across AZs. Option B is wrong because Route 53 is not needed for internal distribution. Option D is wrong because target group health checks are already enabled.
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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