A small Go snippet demonstrating how to use a custom DNS resolver to lookup IPs.

custom-dns-resolver.go

package main

import (
	"context"
	"fmt"
	"net"
	"time"
)

func main() {
	customResolver := &net.Resolver{
		PreferGo: true,
		Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
			return net.Dial(network, "1.1.1.1:53")
		},
	}

	timeout := 10 * time.Second
	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()

	ipAddrs, err := customResolver.LookupIPAddr(ctx, "example.com")
	if err != nil {
		if ctx.Err() == context.DeadlineExceeded {
			fmt.Println("DNS lookup timed out!")
		} else {
			fmt.Println("Error:", err)
		}
		return
	}

	for _, ipAddr := range ipAddrs {
		fmt.Printf("%s\n", ipAddr.String())
	}
}