In general try to use the newest version, AutoCadLight - 2013. But it really relates to the App you will use to open the DXF. If your AutoCad is newer than 2013 then that would answer the question. If it is an older version of AutoCad, the dates are in the names on the EazyDraw export popup menu.
Note: You should try SVG, DXF is rather crude an problematic. If your work flow will be to a laser cuter, 3d printer, something in anyway current - , skip the DXF AutoCad step and use SVG. If you end driver doesn't support SVG, look for a better one.
Remember for a DXF export you will need to move the origin of the drawing to the lower left of the page and set y-axis to plus -> up. The is on Scale palette in EazyDraw.