Which of the following salts, does not undergo hydrolysis?

KCN is the salt of strong base KOH and weak acid HCN.

$ZnS{O}_4$  is the salt of weak base $Zn(OH{)}_2$ and strong acid H2SO4

CdS is the salt of weak base $Cd(OH{)}_2$ and weak acid $H_{2}S$

$NaCl{O}_4$ is the salt of strong acid $HCl{O}_4$  and strong base NaOH.