gethostbyname() Showing wierd results while domain validation

Question

This is the code iam using for validating the domain name using gethostbyname().

This is working fine until i use it on localhost.

As soon as i upload it on my server,gethostbyname() started returning ip address of the unknown domain name as well.

$url=$_GET['d'];
function getHost($Address) { 
           $parseUrl = parse_url(trim($Address)); 
           return trim($parseUrl['host'] ? $parseUrl['host'] : array_shift(explode('/', $parseUrl['path'], 2))); 
        }

  $get=getHost($url);
  $domain = str_ireplace('www.', '', $get);

 if(filter_var(gethostbyname($domain), FILTER_VALIDATE_IP))
{
echo gethostbyname($domain);
echo $domain;
}
else
{
echo gethostbyname($domain);
   echo "Not Valid";
}

My test cases are :-

1)www- it return 184.173.134.234

2)google.coma- it returns 67.215.65.132

3)google.comaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa - it returns 67.215.65.132

One more interesting thing happening is that for these same domain name when i run them on my localhost .this same function returns Not valid.

Any help would be appreciated :)

Answer 1

Based on the answer and research by Ben D...

# Get the URL from the GET Parameters
$url = $_GET['d'];

# Derive the HTTP Host
$hostname = parse_url( $url , PHP_URL_HOST );
# Strip the "WWW." from the hostname if present
$hostname = preg_replace( '/^www\./i' , '' , $hostname );

# Look for the IP Address
$ip_address = gethostbyname( $hostname );

if( filter_var( $hostname , FILTER_VALIDATE_IP ) ){
  echo 'Hostname is an IP Address already';
  echo $hostname;
}elseif( $ip_address==$hostname || $ip_address=='67.215.65.132' ){
  echo 'Domain Not Found';
}elseif( filter_var( $ip_address , FILTER_VALIDATE_IP ) ){
  echo $ip_address;
  echo $hostname;
}else{
  echo 'Invalid IP Address Returned';
  echo $ip_address;
  echo $hostname;
}