They do indeed have one (or more depending on cage size) designated areas for doing that. The specific place you put the litter box is something you teach them,

They do indeed have one (or more depending on cage size) designated areas for doing that. The specific place you put the litter box is something you teach them, but they don't need much training to learn as they do seem to naturally do this with spots they choose themselves too. Of course it might happen occasionally outside of those areas too, but if that starts happening frequently it can be a sign that something is wrong with them health wise.