How can I check if a particular IP is a server?

I figured out how to generate a list of all the IP addresses on my local network, and what I want to do is check each one to see if it is running my game as a server, perhaps through some sort of ping function. Is there any function Unity can perform to do this? My goal is to create a multiplayer LAN game where instead of requiring internet access to reach the Master Server players can start their own servers and connect with each other through the LAN, in a similar manner to games like Halo. This seems like it should be a pretty basic function but I've trawled the web and searched through UnityAnswers and come up with no leads.

I haven't used Unity networking, but it looks like you could call Network.Connect with an invalid password and use the returned error to determine whether you got refused or there was no server there at all.