func (mx *RDataMX) String() string {
	var b strings.Builder
	fmt.Fprintf(&b, "{Preference:%d Exchange:%s}", mx.Preference,
		mx.Exchange)
	return b.String()
}
String return readable representation of MX record.
package dns
import (
	"fmt"
	"strings"
	libnet "github.com/shuLhan/share/lib/net"
)
const (
	defMXPreference int16 = 10
)
type RDataMX struct {
	Preference int16
	Exchange string
}