Do all C# casts result in boxing/unboxing

Question

I am curious to know if all casts in C# result in boxing, and if not, are all casts a costly operation?

Example taken from Boxing and Unboxing (C# Programming Guide)

Answer 1

No.

Boxing means putting a value into a new reference type instance.

Standard casts between reference types do not result in any allocations.
(User-defined casts can do anything)