  The pointlike impurity scattering is studied for a superconductor with
different pairing symmetries based on a minimal two band model proposed by S.
Raghu $et$ $al.$ [Phys. Rev. B {\bf 77}, R220503 (2008)], and the
self-consistent Bogoliubov-de Gennes equations. Two intra-gap resonance peaks
are found at or near the nonmagnetic impurity site for a typical $s_{x^2y^2}$
symmetry and strong scattering potentials. Such intra-gap resonance peaks are
absent for the sign unchanged s-wave and $d_{x^2-y^2}$-wave order parameter.
Thus we propose that a non-magnetic impurity with strong scattering potentials
can be used to probe the pairing symmetry in iron-based superconductors.
