Catalyzes the sodium-dependent uptake of extracellular D-alanine and glycine. D-alanine(in) + Na(+)(in) = D-alanine(out) + Na(+)(out) glycine(in) + Na(+)(in) = glycine(out) + Na(+)(out) Belongs to the alanine or glycine:cation symporter (AGCS) (TC 2.A.25) family.