Common practices for device auto finding?

What are the best, or most common, ways of employing "auto finding" for a device/computer over wifi? Do you just do a UDP broadcast and response? When broadcasting do you only broadcast to your subnet or to everything? or Arp? or scan through every IP for the host-part and hope t connect? I was thinking of doing a UDP broadcast only to whatever subnet the device is connected to. Specifically, I'm working on an android-pc solutio开发者_C百科n.

I'm not sure about the wifi specific part of your question but the fact you ask about network level stuff like UDP makes me link you would be interested in what Apple calls Bonjour or was called Zeroconf in the IETF. There is Bonjour support for android out there although I've never worked with it.