.NET and C# interview questions

A delegate is a type-safe function pointer.

Generics keep type safety and avoid boxing of value types.

Transient is a new instance every resolve.

The context snapshots entity instances and generates INSERT, UPDATE, or DELETE on SaveChanges.

I Include the navigation I need, or project to an anonymous type or DTO in one Select.

Ref passes a variable that must already be assigned and can be read and written.

Records are reference types with value-based equality and a concise init syntax.

Exceptions are for unexpected failures

The pool reuses worker threads for Tasks and I/O completions.

The GC frees unreachable objects, but event handlers, static caches, and forgotten subscriptions keep objects reachable.

Async await frees threads while waiting on I/O without blocking.

The Common Language Runtime runs .NET bytecode, handles memory with GC, and provides security and type safety.

An interface defines a contract of members a type must implement.

Middleware forms a pipeline that handles each HTTP request: logging, auth, routing, endpoints.

They wrap the whole file in a namespace without nested braces.

It declares constructor parameters on the type itself and can capture them as fields.

required forces object initializers or constructors to set those properties.

It provides atomic increments and compare-exchange without a full lock.

Task.Run is the modern short form for offloading to the thread pool.

Thread-safe dictionary operations without a coarse lock for every access.