Which command would create a valid ipv6 default route?

The default route is a route that allows a router to forward packets even though its routing table contains no specific route to the destination network.

The command that creates a valid IPv6 default route is the following:

ipv6 route : : / 0 2001:db8:acad:2::a

::/0 is the prefix and prefix length for a default route is : : / 0. This matches any address.