  We investigate the existence of chiral zero modes at a^{-1} \simeq 1 GeV in
quenched domain-wall QCD. Simulations are carried out for the plaquette and an
RG-improved gauge actions on a 12^3x24xN_s lattice with N_s=10-50. We find that
the pion mass in the chiral limit remains non-vanishing as N_s\to\infty for
both gauge actions. Possible origins of this non-vanishing pion mass are
discussed.
