I got similer question in my CCIE written exam. Above command will installed default route Cust1 vrf routing table and not in global routing table
Having a static route with a global keyword in the Cust1 VRF ensures that all packets destined to the Internet are routed to the Internet gateway and subsequently to the Internet.
For reference se below ink
http://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/24508-internet-access-mpls-vpn.html
Kindly rate for useful post
Regards,
Pawan