AZ-900 Practice Question 65: App Service Deployment Slots
Microsoft Azure Fundamentals (AZ-900) · Test 7 · question 5 of 10
A team hosts its production web app on Azure App Service. Before every release, they want to deploy the new version to a separate, fully warmed-up copy of the app, then switch that copy into production so that no requests are dropped, and be able to reverse the switch immediately if something goes wrong. Which App Service capability provides this?
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Answer:
Deployment slots are live apps with their own hostnames. Deploying to a nonproduction slot lets you validate app changes and make sure every instance is warmed up before it swaps into production, which "eliminates downtime when you deploy your app. The traffic redirection is seamless. No requests are dropped." If the swapped-in version misbehaves, you "perform the same swap immediately to get your last known good site back", exactly the rollback the team wants.
Option A, scaling out, adds capacity to whatever version is already running; it doesn't stage a new version anywhere for validation. Option C describes the manual, downtime-prone pattern deployment slots exist to replace; DNS changes propagate gradually and aren't instantly reversible. Option D, autoscale, reacts to load metrics on the current deployment; it has no role in staging or validating a new one before it reaches users.