/etc/resolv.confを変更せずにGolangでLookupTXTを実行する方法は?

import (
    "log"
    "net"

    "github.com/miekg/dns"
)

func main() {
    target := "microsoft.com"
    server := "8.8.8.8"

    // Create a new DNS client with a custom server.
    c := dns.Client{Net: "udp", Server: server}

    // Build a request message.
    m := dns.Msg{}
    m.SetQuestion(target+".", dns.TypeTXT)

    // Exchange the request and receive the response.
    r, _, err := c.Exchange(&m, server+":53")
    if err != nil {
        log.Fatal(err)
    }

    // Process the response.
    if len(r.Answer) == 0 {
        log.Fatal("No results")
    }
    for _, ans := range r.Answer {
        TXTrecord := ans.(*dns.TXT)
        for _, txt := range TXTrecord.Txt {
            log.Println(txt)
        }
    }
}