Masking sensitive configuration data?

Short answer: ✅ Best practices: Don't log sensitive values Use [JsonIgnore] or remove values before logging Mask in logs manually: _logger.LogInformation("Token: {Token}", Mask(token)); Never store secrets in source-controlled files (appsettings.json) Use user-secrets, Key Vault, or environment variables instead Authentication & Authorization (JWT, Identity)

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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.