Useage: ./ip http://<domain>/<endpoint>

main.go

package main

import (
	"encoding/binary"
	"fmt"
	"log"
	"net"
	"net/url"
	"os"
	"strconv"
)

func main() {
	u, err := url.Parse(os.Args[1])
	if err != nil {
		log.Fatal(err)
	}

	ip, err := net.ResolveIPAddr("ip4", u.Host)
	if err != nil {
		log.Fatal(err)
	}

	ip4 := ip.IP.To4()
	u.Host = strconv.FormatInt(int64(binary.BigEndian.Uint32([]byte{ip4[0], ip4[1], ip4[2], ip4[3]})), 10)
	fmt.Println(u.String())

}