What is content negotiation, how ASP.NET Core chooses media

Short answer: types Automatically selects response format (JSON, XML) based on Accept header. Configured via formatters in MVC options. Falls back to default formatter if no match.

Real-world example (ShopNest)

ShopNest registers AppDbContext as Scoped and IMemoryCache as Singleton. Putting DbContext in a Singleton causes threading bugs.

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.