defer cancel()
		_, h, err := r.exchange(ctx, tt.server, tt.question, time.Second, useUDPOrTCP, false)
		if err != nil {
			t.Error(err)
			continue
		}
		if h.RCode != tt.rcode {
			t.Errorf("got %v from %v; want %v", h.RCode, tt.server, tt.rcode)
			continue
		}
	}
}

func TestDNSTransportNoFallbackOnTCP(t *testing.T) {
	fake := fakeDNSServer{

	return printUint16(uint16(o))
}

// An RCode is a DNS response status code.
type RCode uint16

// Header.RCode values.
const (
	RCodeSuccess        RCode = 0 // NoError
	RCodeFormatError    RCode = 1 // FormErr
	RCodeServerFailure  RCode = 2 // ServFail
	RCodeNameError      RCode = 3 // NXDomain
	RCodeNotImplemented RCode = 4 // NotImp
	RCodeRefused        RCode = 5 // Refused
)