Value in the MAC destination field when using an unnumbered interface?

Question

Cisco

For example, there is a network between two routers. Static routes are registered in them, but as the next hop, the outgoing interface to each other is registered, then what value will be in mac destination (if we use ethernet).

Answer 1

In theory, it should be like this:
First, the sending router will try to find out what MAC address the host with the desired destination IP has, that is, it will try to send a standard ARP request. If no one answers, then the status for such an entry will be Incomplete, respectively, there will be no MAC address.
In order for another host to respond to an ARP request, it must have such an address itself or proxy ARP is enabled.
If two routers are connected to each other, then there will be the MAC address of the neighboring router in outgoing packets.
Someone tried it in practice:
supportforums.cisco.com
And here they also talk about the disadvantages of such an undertaking:
learningnetwork.cisco.com