In C#, how do classes differ from structs, and when would you use each? Explain async/await in C#. How does it improve responsiveness without creating new threads? What is the purpose of IDisposable, and how do using statements/declara­tions ensure deterministic cleanup? Compare IEnumerable, IQueryable, ICollection, and List—when do you choose each? What are boxing and unboxing in C#, and why can they hurt performance? Describe the MVC pattern. How do Models, Views, and Controllers collaborate in ASP.NET MVC? What are Action Filters in MVC? Name common filters and typical use cases. Differentiate ViewData, ViewBag, and TempData. When is each appropriate? How do you implement validation in MVC (server-side and client-side)? Explain the ASP.NET Core request pipeline. What are middlewares and their execution order? How does Dependency Injection work in .NET Core? Describe Singleton, Scoped, and Transient lifetimes. What is the Options pattern (IOptions, IOptionsSnapshot, IOptionsMonitor) and when would you use each? How do you configure logging and health checks in ASP.NET Core? Minimal APIs vs Controllers in ASP.NET Core—trade-offs and when to choose each. In EF Core, what’s the difference between tracking and no-tracking queries? When use AsNoTracking()? How do you manage EF Core migrations in a CI/CD pipeline? In React, why prefer functional components with Hooks over class components? Explain useEffect and the dependency array. How do you prevent infinite re-renders? Compare React Context with Redux (or Zustand) for state management. When choose which? What techniques do you use to optimize React performance and minimize unnecessary re-renders?