They are told not to do that. if they do it intentionally after leering that the Prophet salla Allahu alaihi wa sallam told us not to do it, they have to make up for that day. But if it was done by mistake, there is no need to make up for that day and one should be more careful.

Sheikh, when making wudhou if someone sniffs water in the nose and some amount of water goes down the throat.Does that invalidates the fast. If this happened to a person do they have to fast another day because they broke their fast. JazakAllah Khair.