Which path planner is chosen if unspecified?

Hi, I am using ros-groovy with the ur5 package and I would like to get some information about the path planners. First is, if I do not specify a specifiy path planner, which one is being chosen? Or is there a default one? And second (still no specific solver chosen), after the path planning, can I get the name of the solver which was being chosen? I would like to do a performance benchmark of the various solvers.