Well I have had a decent amount of Netware 3 & 4 experience, a little bit of AS400 - horrid things the little ones, used various flavours of multi user DOS. Too busy programming to get too involved with Windows networking.
Been using the XBASE family languages now for over 20 years and use the most powerful database engine of that family Advantage Database Server - know it pretty well and have done various jobs with the clients including wrappers to the Windows API for a VB programmer, the languages I mainly use are use it natively.
My next job is to learn C++, I know enough C and OOP to read C++ but not write it from scratch.
As to XBASE I have used the compiler versions - currently Visual Objects, and maintenance of Clipper applications, (ones I mainly wrote).
I get a bit of flack of some people as I am very pessimistic over locking and never leave it to the client or the server, prefering to tell the server when I want it locked, rather than let it decide, but this is mainly 20 years of experience and managing to never write an application capable of deadly embraces.