DOP-C02 Resilient Cloud Solutions Practice Question
A company runs a containerized application on Amazon ECS with Fargate launch type. The application experiences intermittent failures when the ECS service scheduler attempts to place tasks during a deployment. The DevOps engineer notices that tasks fail to start due to insufficient IP addresses in the VPC subnets. What is the MOST resilient solution to prevent this issue?
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
✓
Configure the ECS service to use multiple subnets with larger CIDR blocks across multiple Availability Zones.
Using a larger CIDR block for subnets provides more IP addresses, and using multiple subnets across Availability Zones increases availability and capacity. Option A is wrong because increasing desired count does not solve IP shortage. Option B is wrong because ECS service-linked role does not affect IP allocation. Option C is wrong because VPC endpoints do not provide IP addresses for tasks.
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 ECS service-linked role with permissions to allocate IPs.
Why it's wrong here
An ECS service-linked role only grants ECS the permissions to call EC2 APIs on your behalf, such as creating and attaching ENIs; it has nothing to do with the number of IP addresses available. IP exhaustion in a subnet is a capacity planning issue, not a permissions issue. The service-linked role already includes the necessary EC2 permissions, and adding extra permissions cannot expand the subnet CIDR or free up consumed addresses.
- ✗
Increase the desired task count in the ECS service to pre-warm IP addresses.
Why it's wrong here
Setting a higher desired task count does not pre-warm IP addresses; each task in awsvpc mode immediately consumes one primary private IP from the subnet's pool. Increasing the desired count would actually consume more IPs and worsen the exhaustion, not relieve it. There is no AWS mechanism that reserves or caches IPs for tasks before they run, so this approach directly counteracts your goal.
- ✗
Use VPC endpoints for ECS to reduce IP usage.
Why it's wrong here
Interface VPC endpoints create their own elastic network interfaces and consume IP addresses from the subnets where they are deployed, making the shortage worse rather than better. They provide private connectivity to services like Amazon ECS API or Amazon ECR, but they do not affect the per-task ENI allocation or the available IP count in the task subnets. Reducing ECS IP usage requires addressing subnet CIDR size, not the route path to control-plane services.
- ✓
Configure the ECS service to use multiple subnets with larger CIDR blocks across multiple Availability Zones.
Why this is correct
Deploying the ECS service across multiple subnets with larger CIDR blocks increases the total number of usable private IP addresses in different Availability Zones, allowing additional tasks to be launched. Since each awsvpc-mode task requires an ENI with its own private IP, a larger IP pool directly solves the exhaustion. Using multiple AZs also improves availability by spreading tasks across fault domains, making this the appropriate corrective action.
Visual reference
Go deeper
Related to this question
About these practice questions
One of 1,298 original DOP-C02 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
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.