Yes, they did
NO. In a true peer to peer there is no server.
Distinguish between Peer-to-Peer and server based networks
Almost all modern day operating systems support peer to peer networking, and are usually the standard network protocol after a new installation.
It is possible that they do; the reason for this is that in a peer to peer network each workstation is responsible for their own security, backups, virus protection, etc. You can not mandate tool usage in a peer to peer network. In a client server network you can force policies to be obeyed, but not in a peer to peer network.
A peer-to-peer network is not required for have a server at all. Therefore, any peer-to-peer network could be formed without a server.
Peer-to-peer
Nope. There is no server in peer to peer networks. Only client computers connected to each other.
A peer-peer server is a computer network in which all the computers are equal, as opposed to a client-server network in which the computers get permission from an administrative computer. All computers in a peer-peer network can share and access available data freely.
A host in a peer to peer network can offer resources to other hosts or devices in the network without being a server. If you share a printer, or a folder across the network you are sharing information or resources with other devices; in each case neither system is a server. The ability to do this is built in to most desktop client operating systems.
In a peer to peer network, all nodes are the same. In a client-server network, conversely, the server node maintains control over other nodes.
peer-to-peer and server-based
The question does not fully make sense , but as far as I understood - any unix based OS is good for you.