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 Go 1.9 this is possible by overriding the Dial function on a Resolver. For example, to ignore the request for the local resolver over UDP and connect to 9.9.9.9 via TCP we might do something like this:

r := &net.Resolver{
    Dial: func(ctx context.Context, _, _ string) (net.Conn, error) {
        return net.Dial("tcp", "9.9.9.9")
    },
}
addrs, err := r.LookupIPAddr(context.TODO(), "example.net")