Defining servers from HA cluster

I have a cluster of (two) database servers (HA/ High Availability). My application connects to one of them (active) at a time. The other one remains passive and always ready to get connected when the active one fails over.
It’s a typical Windows cluster mechanism. Now I have a challenge to handle these two servers, but how can I let the my app know which one to be connected, since both (active & passive) ned to be registered in consul.