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AZ-400 Practice Question: A team is designing a release pipeline for a .NET…
A team is designing a release pipeline for a .NET Core web application. They want to deploy to Azure App Service using a blue-green deployment strategy to minimize downtime. Which Azure App Service feature should they use to implement this?
⚠ Common exam trap
Test-takers frequently confuse Azure Traffic Manager or Load Balancer as necessary for blue-green deployments, but Azure App Service's built-in deployment slots with swap operation are the correct and simplest implementation for this specific service.
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 deployment slots with swap operation.
Deployment slots in Azure App Service support swap operations that enable blue-green deployment by swapping the production slot with a staging slot. This minimizes downtime because the swap is warm-up and validation is done in the staging slot before traffic is redirected, and the swap itself is instantaneous under the hood. No external load balancer or traffic manager is needed because the swap operation handles the routing internally.
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 Azure Load Balancer in front of two separate App Services.
Why it's wrong here
Azure Load Balancer in front of two separate App Services is unnecessarily complex because it requires managing two distinct App Service instances, each with its own settings and deployment, and does not provide the native warm-up and traffic-shifting capabilities that App Service deployment slots offer. It also fails to address the need for zero-downtime application code swaps during release, as it only distributes traffic based on backend health, not versioned deployments.
- ✓
Use deployment slots with swap operation.
Why this is correct
Deployment slots with swap operation are the correct choice because they enable blue-green deployment: the new release is deployed to a staging slot, validated, and then swapped with the production slot, making the new version live with zero downtime. App Service automatically handles slot swap by warming up the target slot and preserving production settings, and the swap operation allows instant rollback if issues arise, which is ideal for a .NET Core web app release pipeline.
- ✗
Configure auto-scaling rules.
Why it's wrong here
Auto-scaling rules are designed to adjust the number of running instances in response to load metrics (e.g., CPU percentage or request count), but they do not control how application code is deployed or released. They cannot perform a version switch or manage the transition from an old build to a new one; they only scale out/in horizontally, so they are irrelevant for a release pipeline's deployment strategy.
- ✗
Use Azure Traffic Manager to route traffic between slots.
Why it's wrong here
Azure Traffic Manager is a DNS-based traffic router used to distribute traffic across globally deployed endpoints for latency, priority, or geographic routing, not for swapping between deployment slots—slots already share the same hostname, and Traffic Manager cannot trigger a slot swap operation. Using Traffic Manager between slots is an anti-pattern because it would require slot URLs to be exposed as endpoints and does not provide the atomic, warm-up-aware swap that App Service's native swap mechanism does.
Go deeper
Related to this question
Learn chapter
Introduction to DevOps and Azure DevOps
Key term
Feature
A feature is a distinct unit of functionality that delivers value to the user, often managed and tracked throughout the software development lifecycle.
Key term
Blue-green deployment
Blue-green deployment is a release strategy that reduces downtime and risk by running two identical production environments, one live and one idle, enabling instant traffic switching between them.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-400 practice question is part of Courseiva's free Microsoft 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 AZ-400 exam.