A router usually can link only LANs with the identical protocol. Like bridges, routers restrict a LAN's local traffic to itself, passing data on the bridged LAN only when the data is specially intended for it. A way of ensuring that data on a LAN is protected from unauthorized use. Network security measures can be software-based, where passwords restrict users' access to certain data files or directories. This kind of security is usually is implemented by the network operating system.
Audit trails are another software-based .
A computer providing a service to LAN users, such as shared access to disks, files, a printer, or an electronic mail system. Usually a combination of hardware and software. A logical network connection between two workstations for the exchange of data. Also a data conversation between two devices. It is possible to have more than one session going between two devices simultaneously.