When configuring a static route, certain parameters are required for the route to function correctly. Let us analyze each option:

Option A :

Incorrect : The preference (or administrative distance) is optional. If not specified, the router uses the default preference value for static routes.

Option B :

Incorrect : While the next-hop IP address is commonly used in static route configuration, it is not always mandatory. For example, you can specify an outgoing interface instead of a next-hop address.

Option C :

Incorrect : The subnet mask is essential for defining the network prefix of the destination network. Without the mask, the router cannot determine the range of IP addresses covered by the route.

Option D :

Correct : The subnet mask is mandatory when configuring a static route. It defines the network portion of the destination IP address, enabling the router to match packets to the correct route.

Thus, the correct answer is D .

References:

HCIA Huawei ACCESS Official Documentation , Chapter: Static Route Configuration.

IP Routing and Subnet Masks by Huawei.