Why golang Lookup*** function can't provide a server parameter?

Question

For nslookup command, it has nslookup somewhere.com some.dns.server.

However, it seems that golang dnsclient only load config from /

Answer 1

Since a little while you can set the Dial for the Resolver, where you can define your nameserver in the DialContext

var resolver *net.Resolver

if nameserver != "" {
    resolver = &net.Resolver{
        PreferGo: true,
        Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
            d := net.Dialer{}
            return d.DialContext(ctx, "udp", net.JoinHostPort(nameserver, "53"))
        },
    }
} else {
    resolver = net.DefaultResolver
}

After that you can go as you're used to:

ips, err := resolver.LookupIPAddr(context.Background(), "www.example.com")