JSFiddle - React, Tailwind, and code Playground

HTML

<form name="ipAddress">
<div id="ipRange">
    <div id="ipRange1">
        1. From: <input type="text" name="ipfrom" /> To: <input type="text" name="ipto" /><input type="button" onClick="validate('ipRange1');" value="Validate">
    </div>
</div>
    <input type="button" value="Add" onClick="addIpRange();"/>
</form>

JavaScript

var ipIndex = 1;
    var validIp = /^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$/;
    
    function addIpRange(){
        
        var ipDiv = document.getElementById('ipRange');
        var newDiv = document.createElement('div');
       
        ipIndex++;
        newDiv.innerHTML = ipIndex + '. From: <input type="text" name="ipfrom" /> To: <input type="text" name="ipto" /><input type="button" onClick="validate(\'ipRange' + ipIndex + '\');" value="Validate">'
        newDiv.setAttribute('id', "ipRange" + ipIndex);
        ipDiv.appendChild(newDiv);
    
    }
    
    function validate(id){
    
        var divToCheck = document.getElementById(id);
        
        var ipAdress = divToCheck.getElementsByTagName('input');
        var ipFrom = document.getElementById(id).childNodes[1].value;
        var ipTo = document.getElementById(id).childNodes[3].value;
        
        if(validIp.test(ipFrom)){
            if(validIp.test(ipTo)){
                if(ipFrom > ipTo){
                    alert("Invalid Ip Range");
                } else {
                    alert("Valid Ip Range");
                }
            } else {
                alert("Invalid Ip Address [To]");
            }
        } else {
            alert("Invalid Ip Address [From]");
        }        
    
    }