A network is a set of devices connected by physical media links. A network is
recursively is a connection of two or more nodes by a physical link or two or more networks
connected by one or more nodes.
A network can consist of two or more computers directly connected by some physical medium
such as coaxial cable or optical fiber. Such a physical medium is called as Links and the computer it
connects is called as Nodes.
What are the criteria necessary for an effective and efficient network?
It can be measured in many ways, including transmit time and response time.
It is measured by frequency of failure, the time it takes a link to recover from a failure,
and the network's robustness.
Security issues includes protecting data from unauthorized access and virues.