MRB zeroing

I know that this has been covered in the past but but since the
archives are down I ask again.
Someone in the past gave CL input to zero the mrb and it went
something like this:
=09dd if=3D/dev/zero of=3D/dev/hda ibs=3D512 obs=3D512
If someone can confirm or modify this so it it usable I would
appreciate it.

TIA
Clayton Stapleton