I'm sure this has been discussed, but I couldn't find anything. I know you don't earn elite qualifying segments for Delta flights. However...

Does the same apply to NW-coded, DL-operated flights? I am thinking not.

Also, do you get segments for a DL-coded, NW-operated flight? Here I would think you do, but want clarification from someone who has done it. I'm finding fares much cheaper on NW if I book it with the DL code.