DVA-C02 Deployment Practice Question
A company is implementing a CI/CD pipeline for a containerized application using Amazon ECS and AWS CodePipeline. The team wants to ensure zero-downtime deployments. Which THREE strategies should the team implement? (Choose THREE.)
⚠ Common exam trap
The trap is selecting options that sound like they improve deployment but actually cause downtime, such as 'rolling update with 100% batch size' or 'stop all tasks first'; candidates must recognize that zero-downtime requires maintaining capacity and gradually shifting traffic.
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 an Application Load Balancer.
Option A is correct because a blue/green deployment with an Application Load Balancer lets CodeDeploy shift traffic from the original ECS task set to the new (green) task set only after the new tasks pass health checks, and it can roll back instantly if validation fails, so users never hit a failed deployment. Option C is correct because ECS service auto scaling keeps the desired task count at the level the service needs during and after deployment, ensuring enough healthy tasks remain registered with the load balancer to absorb traffic while replacements are being launched. Option D is correct because the health check grace period prevents ECS from killing newly started tasks before they have finished booting and begun responding to ALB health checks, avoiding false unhealthy verdicts that would otherwise cause task churn and downtime. Option B is not appropriate because a rolling update with a batch size of 100% replaces all tasks at once, which removes all healthy capacity simultaneously and can cause an outage. Option E is not appropriate because stopping all existing tasks before starting new ones creates a hard outage, directly violating the zero-downtime requirement.
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 an Application Load Balancer.
Why this is correct
A blue/green deployment provisions an entirely new (green) set of ECS tasks alongside the running (blue) set, and the ALB shifts traffic over only once the green tasks pass health checks. Because the old environment stays live until cutover, users never hit a moment with zero healthy targets, and rollback is instant by simply routing back to blue.
- ✗
Use a rolling update with a fixed batch size of 100% of tasks.
Why it's wrong here
Setting the minimum healthy percent effectively to 0 (a 100% batch replacement) tells ECS it may stop all existing tasks before any replacement tasks are running and healthy, which creates a window with no active targets behind the load balancer and directly causes downtime during the deployment.
- ✓
Use ECS service auto scaling to maintain desired count during deployment.
Why this is correct
ECS service auto scaling keeps the desired task count aligned with load throughout the deployment, preventing the service from being under-provisioned while old and new tasks coexist; without it, capacity could dip below what's needed to serve traffic during the transition, undermining continuity even if the deployment strategy itself is sound.
- ✓
Configure the ECS service with health check grace period.
Why this is correct
The health check grace period tells the ALB and ECS to wait a defined interval after a task starts before failing it for not yet responding to health checks, giving the application process time to initialize; without this grace period, slow-starting containers could be killed prematurely, causing task churn and dropped requests.
- ✗
Stop all existing tasks before starting new tasks.
Why it's wrong here
Stopping every existing task before launching replacements guarantees a gap with zero running tasks capable of serving requests, which is the direct opposite of a zero-downtime approach; deployments must always keep some minimum percentage of tasks healthy and serving throughout the rollout.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
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.