DVA-C02 Development with AWS Services Practice Question
A company is deploying a containerized application on Amazon ECS using the Fargate launch type. The application must be highly available across multiple Availability Zones. The developer needs to configure the ECS service. Which THREE configuration options are required? (Choose THREE.)
⚠ Common exam trap
Candidates often confuse the EC2 launch type with the Fargate launch type. Auto Scaling groups (Option A) are used to scale EC2 instances in an ECS cluster using the EC2 launch type, whereas Fargate manages the underlying infrastructure serverlessly. Additionally, while external state storage (Option E) is a best practice for stateless applications, it is not an ECS service configuration requirement for high availability.
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
✓
Set the desired number of tasks to at least 2.
Option B is correct because setting the desired task count to at least 2 ensures that more than one task replica runs, which is necessary for high availability so that the service survives the failure of a single task. Option C is correct because associating an Application Load Balancer with the ECS service distributes incoming traffic across the running tasks and performs health checks, enabling traffic to be routed only to healthy tasks in multiple AZs. Option D is correct because configuring the service to place tasks in at least two subnets in different Availability Zones spreads the tasks across distinct AZs, which is the fundamental requirement for multi-AZ high availability in ECS. Option A is not required because AWS Fargate is a serverless launch type that does not use EC2 Auto Scaling groups; scaling is handled through ECS Service Auto Scaling instead. Option E is not required because ECS manages task state internally, and DynamoDB is not part of the ECS service configuration for high availability.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create an Auto Scaling group for the Fargate tasks.
Why it's wrong here
Amazon ECS Fargate tasks run on serverless infrastructure managed by AWS, abstracting away the underlying EC2 instances. Therefore, traditional EC2 Auto Scaling groups are not used to manage or scale Fargate tasks directly. Instead, ECS Service Auto Scaling is configured directly on the ECS service to adjust the desired count of Fargate tasks based on metrics like CPU utilization or request count, making an Auto Scaling group irrelevant for Fargate.
- ✓
Set the desired number of tasks to at least 2.
Why this is correct
Setting the desired number of tasks to at least two is a fundamental practice for achieving high availability and fault tolerance in a containerized application. If a single task becomes unhealthy, crashes, or needs to be replaced during a deployment, the remaining tasks can continue to process requests, preventing service interruption. This redundancy ensures the application remains operational even with individual task failures.
- ✓
Associate an Application Load Balancer with the ECS service.
Why this is correct
Associating an Application Load Balancer (ALB) with the ECS service is crucial for distributing incoming application traffic efficiently across multiple tasks. The ALB performs health checks on individual tasks and routes requests only to healthy instances, ensuring clients connect to operational containers. This also enables seamless blue/green deployments and provides a stable DNS endpoint for the application.
- ✓
Configure the service to place tasks in at least two subnets in different Availability Zones.
Why this is correct
Configuring the ECS service to distribute tasks across at least two subnets in different Availability Zones (AZs) is a critical architectural decision for maximizing application resilience. This strategy ensures that if an entire Availability Zone experiences an outage or becomes degraded, the application can continue to operate without interruption using tasks running in the other healthy AZs. It prevents a single point of failure at the infrastructure level.
- ✗
Use a DynamoDB table to store task state.
Why it's wrong here
Using a DynamoDB table to store task state is not a standard or required configuration step for deploying an ECS Fargate service itself. While application-specific state *within* a containerized application might leverage DynamoDB for persistence, the ECS service configuration and management of tasks do not inherently require or use DynamoDB for their operational state. Task lifecycle and health are managed by the ECS control plane, not an external database for service state.
Visual reference
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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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.