How to find registered cache servers

I support a large educational network with multiple sites. Recently I've discovered that previous engineering resources configured cache servers and left them scattered about the network at various sites. They may (or probably not) be configured properly. I'm curious if there is a way to find a list of all the registered cache servers in the network that are behind our public address space (roughly 6 /24 networks). I want to get this cleaned up this weekend before IOS 8.2 rolls out and I have 4000 iPads destroying my internet access.

Thank you.