Directions Service Algorithm

Hi,

as I have searched through the Forum for an answer regarding this Topic I have seen a lot of answers stating that it is an modified Version of A*, Dijkstra or CH. Hence I would like to ask personally which algorithm is used for the directions. Is it the same even if I use the avoid Polygons feature etc. ?

It would be really helpful to get a definite answer regarding this as it would really help me with my thesis