code: func DefaultErrorFunc(w dns.ResponseWriter, r *dns.Msg, rc int) {
  	state := request.Request{W: w, Req: r}
  
  	answer := new(dns.Msg)
  	answer.SetRcode(r, rc)
  
  	state.SizeAndDo(answer)
  
  	vars.Report(state, vars.Dropped, rcode.ToString(rc), answer.Len(), time.Now())
  
  	w.WriteMsg(answer)
  }
docs: // DefaultErrorFunc responds to an DNS request with an error.