code: public static function findPublishedFallbackByHostname($strHost, array $arrOptions=array())
  	{
  		// Try to load from the registry (see #8544)
  		if (empty($arrOptions))
  		{
  			$objModel = Registry::getInstance()->fetch(static::$strTable, $strHost, 'contao.dns-fallback');
  
  			if ($objModel !== null)
  			{
  				return $objModel;
  			}
  		}
  
  		$t = static::$strTable;
  		$arrColumns = array("$t.dns=? AND $t.fallback='1'");
  
  		if (!static::isPreviewMode($arrOptions))
  		{
  			$time = Date::floorToMinute();
  			$arrColumns[] = "($t.start='' OR $t.start<='$time') AND ($t.stop='' OR $t.stop>'" . ($time + 60) . "') AND $t.published='1'";
  		}
  
  		return static::findOneBy($arrColumns, $strHost, $arrOptions);
  	}
docs: Find the language fallback page by hostname
  
  @param string $strHost    The hostname
  @param array  $arrOptions An optional options array
  
  @return PageModel|Model|null The model or null if there is not fallback page