DOP-C02 Resilient Cloud Solutions Practice Question
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 choices
Why each option matters
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.
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 Route 53 weighted routing is not needed for internal load balancing; the ALB already distributes traffic across AZs. Option B is wrong because configuring health checks to mark instances unhealthy based on AZ instance count would not help with even distribution and could cause unnecessary failures. Option D is wrong because the least outstanding requests routing algorithm optimizes for request queue depth but does not enable cross-zone load balancing; cross-zone load balancing must be explicitly enabled.
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.
- ✗
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.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.