Prior car, knocking noise was the rack and pinion. 100k+ over rough streets had worn the pinion gear. Wasn't a safety issue, didn't affect handling and couldn't feel it in the steering/wheel. Dealer mechanic pinpointed the noise with a stethoscope. I later replaced the rack & pinion myself. The part was $300 at the dealer. Paid a shop to do the alignment though, they didn't really have anything to do as I compared the OEM and replacement to match up the tie-rods.
To state it again, you can't tell whether your rack mount nuts are loose without putting a torque wrench on them. If regular movement is allowed, it may damage the rubber bushings.
To state it again, you can't tell whether your rack mount nuts are loose without putting a torque wrench on them. If regular movement is allowed, it may damage the rubber bushings.