I have a 2000 A6 2.8. I am hearing a front-end knocking noise (drivers side sounds like right by the brake pedal)when i slowly drive over a bumpy road or when I drive slowly and slightly shake the wheel from right to left. Also, the knock began after having my axles rebuilt. Not sure if it was caused by this or if it just happened at the same time.

 

Check the steering rack bolts and the tie rod ends. To check the tie rod ends you have to lift the front wheels and hold onto the tire at 9 and 3 and move back and forth while looking at the tie rod end for play.
The rack bolts are in the cowl area under the battery and by the brake booster ect.