  Using dark matter halos traced by galaxy groups selected from the Sloan
Digital Sky Survey Data Release 4, we find that about 1/4 of the faint galaxies
($\rmag >-17.05$, hereafter dwarfs) that are the central galaxies in their own
halo are not blue and star forming, as expected in standard models of galaxy
formation, but are red. In contrast, this fraction is about 1/2 for dwarf
satellite galaxies. Many red dwarf galaxies are physically associated with more
massive halos. In total, about $\sim 45$% of red dwarf galaxies reside in
massive halos as satellites, while another $\sim 25$% have a spatial
distribution that is much more concentrated towards their nearest massive
haloes than other dwarf galaxies. We use mock catalogs to show that the reddest
population of non-satellite dwarf galaxies are distributed within about 3 times
the virial radii of their nearest massive halos. We suggest that this
population of dwarf galaxies are hosted by low-mass halos that have passed
through their massive neighbors, and that the same environmental effects that
cause satellite galaxies to become red are also responsible for the red colors
of this population of galaxies. We do not find any significant radial
dependence of the population of dwarf galaxies with the highest concentrations,
suggesting that the mechanisms operating on these galaxies affect color more
than structure. However, over 30% of dwarf galaxies are red and isolated and
their origin remains unknown.
