  The Josephson effect in ballistic point contacts between single-band and
multi-band superconductors was investigated. It was found that in the case of
Josephson junctions formed by a single-band and an $s_\pm$-wave two-band
superconductor as well as by a single-band and a three-band superconductor the
junctions become frustrated, demonstrating the $\phi$-contact properties.
Depending on the ground state of a three-band superconductor with broken
time-reversal symmetry (BTRS), the Josephson junction can have from one to
three energy minima, some of which can be locally stable. We also study the
behavior of a dc SQUID based on the Josephson junctions between single-band and
multi-band superconductors. Some features on the dependences of the critical
current and the total magnetic flux on the applied flux of a dc SQUID based on
the Josephson point contacts between a single-band superconductor and an
$s_\pm$-wave superconductor, three-band superconductor with BTRS and three-band
superconductor without BTRS as compared to the conventional dc SQUIDs based on
single-band superconductors were found. The results can be used as an
experimental tool to detect the existence of multi-band structure and BTRS.
