I think I understand now.  I think this feature is to be used when you're using the hub as your internet egress point, because you don't actually have a 0.0.0.0/0 route to advertise into auto-vpn in that instance.  You just have the "baked in" default route on the MX hub from it having an internet connection.  When you have a static default to the core switch, you're advertising that into auto-vpn, and therefore you don't need the box checked and it is indeed redundant.  thanks for the replies! ... View more