An important factor in your system setup is whether your system is a standalone system or a multiuser system that is connected to a host or to a network and is dependent on them.
In a network with many users, one person is usually assigned the responsibility of managing the operation of the computers. This individual, called the system administrator, takes care of starting up and shutting down the computer; connecting terminals, printers, disks, tapes, and modems; backing up files; getting new users started; protecting the system from unauthorized entry; and so on. On a large system, this is often a full-time job in itself, requiring a qualified professional. In general, a UNIX system needs more system administration than a DOS system because of its complexity.
You have a standalone system if it can perform tasks without being connected to a server or host system and if you do not share your system with other users. On a standalone system, you may have to become your own system administrator. If you do, then you must do more than log in and log off when you use your system. Refer to the AIX Version 4 System Management Guide: Operating System and Devices for more information.
You have a dependent system if it must be connected to a host or a server to perform any tasks. This kind of system is typically found in a multiuser or network environment. In this environment, if the server or host stops functioning, your system also stops functioning.
In a multiuser system, there is one main computer, the host, which is shared by everyone. A host computer is the primary or controlling computer that serves the terminals that are connected to it. To use your system, you need to start a session on the host computer. To start a session, you log in.
The main terminal connected to the host is known as the console. The system administrator uses the console to manage the system. The following illustration shows a host system.
A network is a system with computers connected to other computers. Within a network, every computer is called a node. Every node in a system has its own address. In a network, computers play one of two roles: server or client. In some instances, a computer can act as a client to one computer and as a server to another.
A computer on a network that shares its resources or provides a service throughout the network is known as a server. The following are types of servers:
A computer that uses shared resources is known as a client. For example, you may have a UNIX system with its own disk storage where you save some of your files. You, the client, use the file server, which has greater storage capacity, to store other files. If someone on another computer needs to use the files on your computer, they are the client and your system is the server. This is a typical client/server relationship. The following illustration shows a typical client/server network.
