How do you authenticate APIs using bearer tokens?

Short answer: API validates incoming JWT bearer token from Azure AD. Configure authentication in ASP.NET Core: builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationS cheme) .AddJwtBearer(options => { options.Authority = $" options.Audience = clientId; });

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.