NW5.1 Servers Communicating using IP?

I have a WAN consisting of 5 NetWare 5.1 servers which have all been upgraded from 4.11 using the Upgrade/Migration Wizard so they were installed with IP and IPX.

What I would like to know is how do I know/check if the servers are communicating via IP? I need to know this as we are having our WAN upgraded which will stop us from using IPX between buildings..