In IPv6, which type of static route cannot be used if the interface is an Ethernet interface?

In IPv6, a directly attached static route is one that points to a destination network that is directly reachable on the same network segment or interface. This means that if the destination network is directly connected to the router through an interface, such as an Ethernet interface, the router can reach that network without needing to use a next-hop address or any additional routing information.

However, when it comes to static routes in an IPv6 context, directly attached static routes are not applicable if the interface in question is an Ethernet interface. This is because Ethernet interfaces rely on link-layer addressing (MAC addresses) and typically require a layer of abstraction to define the route to a network. Therefore, a directly attached static route would not function as expected in scenarios involving Ethernet interfaces, which necessitates the use of either recursive or fully specified routing methods.

In summary, directly attached static routes are specific to various interface types, and Ethernet interfaces require alternative routing methods for proper functionality, making this the distinguishing factor of this question.