anchor.diff:  %% If there was an OPT RR record in request, it modifies it properly and concates to the ADDITIONAL section.
   %% @end
   %%--------------------------------------------------------------------
  --spec set_reply_code(DNSRec :: #dns_rec{}, ReplyType :: term()) -> #dns_rec{}.
  +-spec set_reply_code(DNSRec :: #dns_rec{header :: #dns_header{}}, ReplyType :: dns_query_handler_behaviour:reply_type()) -> #dns_rec{}.
   set_reply_code(#dns_rec{header = Header} = DNSRec, ReplyType) ->
       ReplyCode = case ReplyType of
                       nx_domain -> ?NXDOMAIN;
  
positive.code: %% @end
  %%--------------------------------------------------------------------
  -spec call_handler_module(HandlerModule :: module(), Domain :: string(), Type :: atom()) ->
      term().
  call_handler_module(HandlerModule, Domain, Type) ->
      case type_to_fun(Type) of
          not_impl ->
  
negative.code:                                                     CurrRec#dns_rec{arlist = CurrArList ++ [RR]}
                                              end
                                      end
                                  end, DNSRecUpdatedHeader, ResponseList),
                              generate_answer(NewRec#dns_rec{arlist = NewRec#dns_rec.arlist}, OPTRR, Transport)
                      end;
                  Error ->
  