Computer Awareness Quiz: Computer Networks

The attack surface of a system is the total collection of every point at which an unauthorised person could try to enter it or pull data out of it: open ports, running services, user accounts, login pages, removable drives and even the employees who can be tricked.

A modulator changes the form of a signal: it loads the digital bits produced by a computer onto an analog carrier wave so that they can travel over a telephone line, a cable or a radio link.

GPRS was added to the 2G cellular system so that the same radio channel could carry data in packets instead of holding a circuit open the way a voice call does.

In a star network every computer has its own cable running to a central hub or switch, so the shape resembles the spokes of a wheel.

In a full mesh every node is joined directly to every other node, so the number of links equals the number of pairs that can be formed from the nodes, given by the formula n(n-1)/2.

A router joins two or more different networks and decides, for every packet, which outgoing line will carry it towards its destination.

The Media Access Control address is the permanent physical address written into the network interface card by its maker, and it is 48 bits long, shown to users as twelve hexadecimal digits in six pairs such as 00:1A:2B:3C:4D:5E. The first half identifies the manufacturer and the second half the particular…

In a ring the machines form a closed loop and a small control frame called a token keeps circulating around it; only the computer holding the token may put data on the ring, and when it finishes it releases the token to the next machine.

The registered jack numbered 45 is the eight-pin plastic plug crimped on the end of an unshielded twisted pair Ethernet cable, and it is what clicks into the network port of a computer, a switch or a router.

Full duplex means both ends can send and receive at the very same moment, and on a telephone call each speaker can talk while still hearing the other, so traffic flows in both directions together.

The Transmission Control Protocol first sets up a connection through a three-way handshake, then numbers every segment, waits for an acknowledgement for each and sends it again if none arrives, and finally hands the data to the application in the original order.

The internet joins networks in every country through undersea cables, optical fibre on land and satellite links, all of them following the common TCP/IP rules, and no single organisation owns it, so it is rightly called the largest wide area network and a network of networks.