Something else for a change: a challenge for the reader.
Given the following topology:
The router does not have any routing protocol configured. It does have all interfaces configured: 10.0.0.1 towards the WAN cloud, 10.0.1.1 towards the PC 2 subnet, and an IP address towards the PC 1 subnet. PC 2 is a Windows computer, static IP 10.0.1.2.
PC 1 is a Windows computer set to DHCP client, but there is no DHCP pool configured on the router or any other device. PC 1 hasn’t had any special changes to the software settings or TCP/IP stack.
Now the question: under what circumstances will PC 1 and PC 2 be able to ping each other?
To my knowledge, this question has two possible solutions. You have an idea? Please share it in the comments!
Update: the solution.
Reggle 
If APIPA is in use on PC1, you can configure a static nat in order to map the ip address
of the interface toward PC1 to the ip address of PC2.
That’s one correct answer!
In the case you configure pc1 with an IP address belonging to the address space of the connected interface to the router and specify a default gateway as the Ip address of that router’s interface…
That’s static setup on PC1. I may have been a bit unclear, but PC1 is set to DHCP. It would work, but not what I’m looking for.
Ipv6 addressing on the link to PC1 (via autoconfig on the PC), and then NAT-PT to allow ping from PC1 to PC2.
Ha! Creative solution, hadn’t thought of that. I was assuming IPv4 only.
However, NAT-PT is deprecated. So there might not be support for it on the router platform.
If APIPA is in use on PC1, you can configure a static nat in order to map the ip address
of the interface toward PC1 to the ip address of PC2.
Second answer can be a reverse of the above one .. NATing the 10.0.1.2 to one APIPA IP
Another possible solution is to give PC1 any ip address you want.
At PC1 create a static ARP pointing to the MAC address of router interface , with the remote address 10.10.1.2 of the PC2.
At PC2 you do the same , just change the address to the ip of PC1 and MAC.
It is a MITM way to get the two PCs connected.