Server Distribution

A client-server systems need not be simple. The basic model is single client, single server

but you can also have multiple clients, single server

In this, the master receives requests and instead of handling them one at a time itself, passes them off to other servers to handle. This is a common model when concurrent clients are possible.

There are also single client, multiple servers

which occurs frequently when a server needs to act as a client to other servers, such as a business logic server getting information from a database server. And of course, there could be multiple clients with multiple servers.