GC752X Ping

I am trying to understand how these switches work.  

I have a GC752X Insight Managed switch.  It is on an isolated management LAN.  There are a total of 7 switches in the 10.200.80.0/24 subnet.  

The Systems Admin guy decided to get on the switch and try pinging the IP address of a server on the Lab network.  It shouldn't work but he tried anyway.  He got a response.  Three responses to be exact.  So did I went I tried it.  

Obviously, something is Proxy ARPing the MAC address and replying for the server.  Who it is I cannot tell.  Since the MAC Address table is just that.  It's a MAC Address table.  There are no IP addresses in the MAC Address table because it is a MAC Address table.  It is not an ARP, or (IP) Address Resolution Protocol table.  I can't determine the MAC address that is replying for that IP address.  

Is there any way to find out on the switch who is replying for the IP address?  Or should I do a Wireshark capture?  

Also, when it does a ping does it only use the management interface(s)? 

Or does it ping out any VLANs created on the switch?

What happens if the default gateway on the switch is itself?  

Thank you.