Degrades NAD into adenosine and nicotinamide riboside, the latter being subsequently internalized by a specific permease. Also endowed with NAD(P) pyrophosphatase activity. Exhibits a broad substrate specificity, recognizing either mono- or dinucleotide nicotinamides and different adenosine phosphates with a maximal activity on 5'-adenosine monophosphate. a ribonucleoside 5'-phosphate + H2O = a ribonucleoside + phosphate Binds 2 Zn(2+) ions per subunit. Belongs to the 5'-nucleotidase family.