I'm playing with the following code:

[ServiceContract]
public interface IUserAccountService
{
    [OperationContract]
    UserAccountResponse CreateNewUserAccount(UserAccountRequest userAccountRequest);
}

public abstract class BaseResponse
{
    public bool Success { get; set; }
    public string Message { get; set; }
}

public class UserAccountResponse : BaseResponse
{
    public int NewUserId { get; set; }
}

My questions are:

1. Do I need to add the DataContract attribute to both the abstract class and the subclass?
2. If the abstract class does not need the DataContract attribute, can I add the DataMember attribure to its properties?