We have performed an evaluation to determine whether or not Neptune's magnetospheric electrons can provide the ionization of Triton's ionosphere as previously suggested or whether photoionization is the dominant ionization mechanism. Our approach has been to determine the accessibility of magnetospheric electrons to Triton's ionosphere. Using scaling relationships based on Venus and Titan observations, we have developed estimates of the centrifugal, gradient B and E¿B drifts. We have computed trajectories of magnetospheric electrons and studied their accessibility to the Triton ionosphere. The following conclusions can be reached from this study: (1) Centrifugal drift delivers electrons to the ionopause. If centrifugal drift is impaired, then electron precipitation is severely limited. (2) Low-energy electrons (E200 km. A magnetized ionosphere would be equivalent to the high ram pressure case for the Venus interaction. A thick ionopause would contribute to prevention of precipitation of magnetospheric electrons into Triton's ionosphere when E<50 keV. Although our calculations at the present level of development cannot rule out the importance of electron precipitation as the source of Triton's ionosphere, we suggest that photoionization be considered viable for the production of Triton's ionosphere.