The Scottish sides learned of their first round opponents yesterday after UEFA made the draw.
Rangers will take on Prishtina, of Kosovo, or St Joseph’s, of Gibraltar, in the first round.
And they now know that should they advance to the second round, it will be either Cork City, Progres Niederkorn or Cardiff Met waiting for them.
Fans will remember Progres after losing to them in a shock result in qualifying two years ago.
Aberdeen will play RoPS, from Finland, in their opening qualifier before potentially facing CS Fola Esch, of Luxembourg, or FC Chikhura Sachkhere, of Georgia, in the second round.
And Killie will go up against Serbian side FK Partizan should they progress past Connah’s Quay Nomads in the first round.
The second round matches are scheduled for July 25th and August 1st.