Can Go\'s Standard Library Specify a Custom DNS Server for Lookup Functions?

Can Go's Lookup Functions Specify a Server?*

Go's dnsclient library seamlessly loads configuration from /etc/resolv.conf, providing essential DNS functionality. However, certain scenarios demand the utilization of a specific DNS server. Does the Go standard library offer a mechanism akin to:

func LookupTXT(name string, dnsServer string) (txt []string, err error)

that can override the default DNS server while maintaining the integrity of /etc/resolv.conf?

Solution

Although the DNS client provided by Go does not directly support specifying a server during DNS resolution, there are alternative approaches to achieve this functionality. One viable option is to leverage the comprehensive dns library developed by miekg:

import (
    "log"

    "github.com/miekg/dns"
)

func main() {

    target := "microsoft.com"
    server := "8.8.8.8"

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

Upon executing this code, you will obtain the resolved IP addresses for the target domain, demonstrating the effective use of a specified DNS server without compromising the system's default configuration.

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