Where are all the large impact craters on Ceres?

http://www.extremetech.com/wp-content/uploads/2016/07/breuqjgajm0dvargnkhm-768x425.jpg 768w, http://www.extremetech.com/wp-content/uploads/2016/07/breuqjgajm0dvargnkhm-640x354.jpg 640w, http://www.extremetech.com/wp-content/uploads/2016/07/breuqjgajm0dvargnkhm-672x371.jpg 672w, http://www.extremetech.com/wp-content/uploads/2016/07/breuqjgajm0dvargnkhm.jpg 1096w" sizes="(max-width: 300px) 100vw, 300px" />Ceres has been in our solar system for 4.5 billion years. Why doesn’t it have any large impact craters? Data from Dawn could offer us answers.