  In the unusual intrinsic QSO redshift models, QSOs are ejected by active
galaxies with periodic non-cosmological reshifts, thus QSOs are generally
associated with active galaxies, and certain structures will be revealed in the
QSO redshift distribution. As the largest homogeneous sample of QSOs and
galaxies, SDSS data provide the best opportunity to examine this issue. We
review the debates on this issue, focused on those based on SDSS and 2dF data,
and conclude that there is no strong connection between foreground active
galaxies and high-redshift QSOs. The existence of two dips in the SDSS QSO
redshift distribution at z=2.7 and 3.5 has recently re-ignited those
controversial debates on the origin of QSO redshift. It also turned out that
both dips are totally caused by selection effects and after selection effects
have been corrected, the two dips disappear and no structure in the redshift
distribution of SDSS DR5 sample. These results support that the reshifts of
QSOs are cosmological.
