In what layer transform Domain into DTO

Hello, in an Asp.Net MVC application the architecture has domain entity classes, DTOs and ViewModels. The ViewModels transformation I make in the controller, so far so good, but at what layer should I make the transformation of domain classes to DTO, is it correct for a repository to return DTO or receive DTO for insertion into the database? The correct would not be working with domain classes in services, business rules layer and repositories and DTO only in the presentation layers?