How do you ensure zero-downtime deployments?

Short answer: Use deployment slots in Azure App Service. Swap staging and production after successful smoke tests. Enable traffic routing gradually using Azure Front Door. Use feature flags to hide new features until fully validated.

Real-world example (ShopNest)

ShopNest on Azure typically uses App Service + SQL Database + Blob Storage + Application Insights for monitoring.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.