Usually, cabin pressure of an airliner is kept at a value corresponding to an altitude of not more than about 2000m.
Now, I heard that before takeoff, the pressure is already increased a little for higher stability of the fuselage. Maybe, this is wrong, but I had another experience:
I was in a 737-800 flying at 11500m. While the aircraft sank on approach for landing, I felt that typical pressure on my ears several times though we still were above 7000m. So, the cabin pressure already changed at that high altitude.
So, how is cabin pressure related to outside pressure during the entire flight?