function ValidateIPaddress(ipaddress) {  
  if (/^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/.test(ipaddress)) {  
    return (true)  
   }  
  //alert("You have entered an invalid IP address!")  
  return (false)  
}  

function ValidateDomainname(domainname) {
   if (/^[a-z0-9]+([-.][a-z0-9]+)*\.[a-z]{2,}$/i.test(domainname)) {  
    return (true)  
   }  
  //alert("You have entered an invalid domain name!")  
  return (false)  
}

function validateDomainForm()
{
    // Validate domain or host name
    var domainname = $("#domainname").val();
    //alert("Domain name: "+domainname);
    
    
    if ($("#PTR").is(":checked"))
    {
       if(!ValidateIPaddress(domainname)) {
         $("#errorMsg").removeClass("hiddenAlert");
         $("#errorMsg").html("<p>Invalid IP address!</p>"); 
         return(false);
      }
      else {
         $("#errorMsg").addClass("hiddenAlert");
         return(true);
      }
    }
    else
    {
      if(!ValidateDomainname(domainname)) {
         $("#errorMsg").removeClass("hiddenAlert");
         $("#errorMsg").html("<p>Invalid Domain Name</p>");
         return(false);
      }
      else {
         $("#errorMsg").addClass("hiddenAlert");
         return(true);
      }
    }
  return true;
}