How did this work?

I have an old Macbook Pro from 2008 running Leopard. I also have a couple newer Macs running Mavericks.

The screen went bad on the Macbook, so I hooked it up directly with a network cable to my home network. The wireless card on the machine was disabled. I figured it would go grab an address through DHCP and I could connect to it and pull files off.

Sure enough, after hooking it up, I could see the machine on the network from the other machines and copy files.

However, when I actually did manage to get back into the Macbook, I noticed that the IP address had been statically assigned for a different network: in other words, it was on a different IP network than the other machines. The wireless card was disabled.

So the question is, how was I seeing that machine on the network? What was it using?

 

172.23.21.200

with a gateway of .1