You will usually stay on the same visa you were on at the DIAC stage when you apply to the RRT. For more information about the different types of visa you could be on at the DIAC stage, please click here.
If the visa you used to come to Australia has not expired then you will still be on that visa when you apply to the RRT. If that visa expires at the RRT stage then you will usually move to a bridging visa when it expires.