Because AppleTalk assigns node IDs dynamically whenever a node joins the network or is rebooted, a node's address on an AppleTalk network can change from time to time, although a computer attempts to reuse the node ID it last used. A zone is a logical grouping of nodes within an AppleTalk internet. The use of zones allows a network administrator to set up departmental or other logical sets of nodes in an internet. Each zone is identified by a unique zone name. A socket is an addressable data-link entity on a network.
Endpoints exchange data with each other across an internet through sockets.
Because each endpoint has its own socket address, a node can have multiple concurrent open connections, for example, one to a file server and one to a printer. A node can have several sockets open at the same time, so each endpoint on an AppleTalk network is associated with a unique 8-bit socket number. Statically assigned sockets are those sockets that are permanently reserved for a designated protocol or process. For example, socket 4 is always reserved as the echo socket, used for echoing packets across a network. In certain situations, you can bind multiple endpoints to a single socket.