No heat both front and rear heating zones

If at first glance the hoses going into and coming out of the heater core are hot, and you are not getting heat out of the ventilation system when the temperature setting is set to the hottest setting, then there could be a problem with the mechanism that blends the temperature inside the vehicle to get to the desired temperature. It would be unusual that both front and rear zones would not work if they have separate temperature controls. If they share one temperature control, then yes - both would be simultaneously affected.