function get_domain($host){  $myhost = strtolower(trim($host));  $count = substr_count($myhost, '.');  if($count === 2){    if(strlen(explode('.', $myhost)[1]) > 3) $myhost = explode('.', $myhost, 2)[1];  } else if($count > 2){    $myhost = get_domain(explode('.', $myhost, 2)[1]);  }  return $myhost; }