You have connected a Multilayer switch to an Internet Service Provider router that has the...

To enable internet access on a multilayer switch, you need to configure a default route that points to the ISP router as the next hop. A default route is a special type of static route that matches any destination IP address that is not found in the routing table. The syntax for adefault route is ip route 0.0.0.0 0.0.0.0 , where 0.0.0.0 0.0.0.0 means any IP address and any subnet mask. Alternatively, you can use the slash notation 0.0.0.0/0 to represent the same thing. Therefore, the correct configuration line to enter on the switch is ip route 0.0.0.0/0 172.16.31.254, which means that any traffic that is not destined for a local network will be forwarded to the ISP router at 172.16.31.254.

The other options are incorrect because they either use the wrong syntax or the wrong IP address. Option A uses the route command instead of the ip route command, which is not valid on a multilayer switch. Option C uses the routing command instead of the ip route command, which is also not valid on a multilayer switch. Option D uses the ip routing command instead of the ip route command, which is used to enable routing on the switch, not to configure a default route. Option D also omits the dots in the IP address and the subnet mask, which makes it invalid.

References:

What Is a Multilayer Switch and How to Use It?

Inter-VLAN Routing Configuration - 2024 Step-by-Step Tutorial

Multilayer Switch - Configuring IP Multilayer Switching