AZ104-Q: Zero-downtime deployment with slots
Q: You want to deploy a new version of an App Service web app, test it, and then make it live without downtime, with the ability to roll back quickly. Which feature do you use?
- A) Deployment slots (deploy to staging, then swap) ✓
- B) Autoscale
- C) Azure Backup
- D) App Service plan resize
Answer: A — Deployment slots. App Service deployment slots let you deploy to a staging slot, validate it, then perform a swap to make it the production slot — with zero downtime and easy rollback (swap back). Autoscale (B) changes capacity, not deployment. Backup (C) is for recovery, not releases. Resizing the plan (D) changes tier/scale, not the deployed version.
Why it helps
Deployment slots = staging/production swap for zero-downtime, testable releases. A standard App Service exam scenario.