DVA-C02 Troubleshooting and Optimization Practice Question
A company runs a monolithic application on EC2 Behind an Application Load Balancer. They want to migrate to a microservices architecture using ECS Fargate. What is the most important optimization to ensure minimal downtime during the migration?
⚠ Common exam trap
Candidates often confuse scaling strategies (horizontal/vertical) with deployment strategies, assuming that adding more capacity or consolidating services will inherently reduce downtime, when in fact only a controlled traffic-shifting method like blue/green with weighted routing ensures minimal disruption during a live migration.
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
✓
Use a blue/green deployment strategy with weighted target groups.
A blue/green deployment strategy with weighted target groups allows you to gradually shift traffic from the existing monolithic EC2 application (blue) to the new microservices on ECS Fargate (green) while monitoring for errors. This minimizes downtime by enabling instant rollback if issues arise, and it leverages Application Load Balancer (ALB) features like stickiness and health checks to ensure a seamless transition without disrupting active connections.
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 a blue/green deployment strategy with weighted target groups.
Why this is correct
A blue/green deployment strategy is ideal for migrating a monolithic application to microservices with minimal downtime. It involves running two identical environments: the existing 'blue' version and the new 'green' version with microservices. Weighted target groups, typically configured on an Application Load Balancer (ALB) or Route 53, allow for a controlled, gradual shift of traffic from the blue to the green environment, enabling real-time testing and easy rollback if issues occur.
- ✗
Increase the EC2 instance size to handle the microservices load.
Why it's wrong here
Increasing the EC2 instance size, known as vertical scaling, is a strategy to enhance the capacity of a single server. However, when migrating to a microservices architecture, especially one leveraging container orchestration services like Amazon ECS with AWS Fargate, the underlying EC2 instance size becomes largely irrelevant. Fargate abstracts away the server infrastructure, managing compute capacity automatically, thus making vertical scaling of specific EC2 instances an inappropriate solution for this migration context.
- ✗
Deploy all microservices in a single ECS service for simplicity.
Why it's wrong here
Deploying all microservices within a single Amazon ECS service fundamentally undermines the core benefits of a microservices architecture. Microservices are designed for independent deployment, scaling, and failure isolation, allowing each component to evolve and operate autonomously. Consolidating them into one service reintroduces tight coupling, creates a single point of failure, and prevents individual scaling based on specific service demands, negating the architectural advantages.
- ✗
Scale horizontally by adding more EC2 instances.
Why it's wrong here
While horizontal scaling by adding more EC2 instances can improve the availability and performance of an existing monolithic application, it does not directly facilitate a controlled, zero-downtime migration to a new microservices architecture. This approach primarily addresses capacity for the current application rather than providing a mechanism for gradually deploying, testing, and transitioning traffic to new, independently deployable microservices without service interruption.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DVA-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 DVA-C02 exam.