Resolve a hostname using a different DNS server

gistfile1.txt

package main

import (
	"flag"
	"fmt"
	"log"
	"net"

	"github.com/miekg/dns"
)

var server = flag.String("nameserver", "192.168.122.1",
	"IPv4 Address of the DNS server.")

func main() {
	flag.Parse()

	if flag.NArg() == 0 {
		return
	}

	if serverIP := net.ParseIP(*server); serverIP == nil {
		log.Fatalf("could not parse nameserver ip %s", *server)
	}

	c := dns.Client{}
	m := dns.Msg{}
	for _, target := range flag.Args() {
		m.SetQuestion(target+".", dns.TypeA)
		r, _, err := c.Exchange(&m, *server+":53")
		if err != nil {
			log.Fatal(err)
		}
		if len(r.Answer) == 0 {
			log.Fatal("No results")
		}
		for _, ans := range r.Answer {
			Arecord := ans.(*dns.A)
			fmt.Printf("%s\n", Arecord.A)
		}
	}
}