Required for high-level resistance to glycopeptides antibiotics. Catalyzes the reduction of 2-keto acids to 2-D-hydroxy acids that give rise to peptidoglycan precursors that terminate in the depsipeptide D-alanine-2-lactate rather than the dipeptide D-alanine-D-alanine thus preventing vancomycin binding. By vancomycin, mediated by VanS/VanR. Belongs to the D-isomer specific 2-hydroxyacid dehydrogenase family.