.NET and C# interview questions

It treats an in-memory sequence as IQueryable so expression trees can be composed.

MapControllers enables attribute-routed controller endpoints.

I return FileStreamResult or Results.File with the right content type and content-disposition.

They run set-based updates and deletes without loading entities into memory.

They eager-load related data in one query.

I add an IsDeleted flag and a global query filter.

Clients present a TLS client cert that middleware maps to a user.

I store the key ring in a shared location and let new keys activate while old ones decrypt existing cookies.

It creates stubs and verifies interactions on interfaces.

I inject an abstraction for UtcNow instead of DateTime.UtcNow directly.

Factory creates short-lived contexts for parallel or background work.

BeginScope attaches properties to subsequent log calls in that block.

The configuration stack layers providers

Formatters choose JSON or XML based on Accept headers when configured.

Attributes inject the caller name for INotifyPropertyChanged or logging helpers.

A field EF maps that does not exist on your CLR type, like UpdatedAt.

Helpers that return strongly typed IResult implementations for OpenAPI metadata.

An async-friendly timer that awaits ticks without callback reentrancy headaches.

It spins real Docker dependencies like Postgres for integration tests.

Server-side caching of endpoint output with policies for duration and tags.