  In this sequel to [L-Y1], [L-L-S-Y], and [L-Y2]
  (respectively arXiv:0709.1515 [math.AG], arXiv:0809.2121 [math.AG], and
arXiv:0901.0342 [math.AG]), we study a D-brane probe on a conifold from the
viewpoint of the Azumaya structure on D-branes and toric geometry. The details
of how deformations and resolutions of the standard toric conifold $Y$ can be
obtained via morphisms from Azumaya points are given. This should be compared
with the quantum-field-theoretic/D-brany picture of deformations and
resolutions of a conifold via a D-brane probe sitting at the conifold
singularity in the work of Klebanov and Witten [K-W] (arXiv:hep-th/9807080) and
Klebanov and Strasser [K-S] (arXiv:hep-th/0007191). A comparison with
resolutions via noncommutative desingularizations is given in the end.
