2nd Part

Question 1

differ in scope from relatively slow wide area networks, employed to transmit messages across vast geographic distances, to very fast local area networks that may connect computers located in the same building

Answer 1

computer networks

Question 2

computers, switches, and terminals interconnected by network links are collectively called _____

Answer 2

nodes

Question 3

its purpose is to provide a connection between nodes that need to communicate

Answer 3

network control

Question 4

the arrangement of nodes and links in a network

Answer 4

topology

Question 5

what are the most widely used topologies?

Answer 5

• hierarchical network
• star network
• ring network
• bus network

Question 6

characterized as:

• a corporate host computer (often a mainframe), divisional minicomputers or powerful workstations, and workgroup support via micros
• matches the organizational structure of many firms and is still frequently used in WANs
• the user workstations may be, in turn, interconnected
  using one of the LAN topologies
• failure of the host does not disable divisional processing, which is a fail-safe feature
• cost-effectiveness of micros and the growing importance of groupwork leads some downsizing firms to move away from hierarchical networks to client/server computing

Answer 6

hierarchical network

Question 7

characterized as:

• a hub computer or switch (such as a PBX) interconnects a number of workstations
• the computer at the hub acts as the network server, providing access to the shared database and software
• all communications between the workstations must go through this central mode
• easy to manage and expand, since in both cases it is largely the single central node that is affected in an expansion of a processing capacity
• the central node is a locus of vulnerability: it may be overloaded or it may fail, disabling the entire network

Answer 7

star network

Question 8

characterized as:

• each node is connected to two of its neighbors
• the nodes are usually close to one another; this topology is frequently used in LANs
• when one node sends a message to another, the message passes through each intermediate node, which restores the signal, as signals deteriorate in transmission
• if a node fails, the ring is out of service, unless the ring contains two channels transmitting in opposite directions

Answer 8

ring network

Question 9

characterized as:

• the nodes on a bus network are connected to a common link such as coaxial cable
• this arrangement is used in LANs
• a failing device does not affect the rest of the network; failure of the bus itself, of course, brings the network down

Answer 9

bus network

Question 10

establish connections between nodes that need to
communicate over a network

Answer 10

switching devices

Question 11

what are the principal techniques for switching?

Answer 11

• circuit switching
• packet switching
• fast packet switching