Lecture 2 - Data Communication Basics

Question 1

What is a ‘Node’

Answer 1

Anything connected to the network, usually a compute, but it could be a printer or a scanner.

Question 2

What is a ‘Segment’

Answer 2

Any portion of a network that is seperated by a switch, bridge or a router from another part of a network.

Question 3

What is a ‘Topology’

Answer 3

The method used to phyically connect nodes to the network.

Question 4

What is a ‘Backbone’

Answer 4

The main cabling of a network that all of the segments connect to. Usually, the backbone is capable of carrying more information than the individual segments.

Question 5

What are the three types of communication media for networks?

Answer 5

Copper - Fibre - Wireless

Question 6

What are the two advantages of Copper cables?

Answer 6

1. Easy to work with, requiring no specialist tools to cut and join cables.
2. Compatible with existing electronic systems.

Question 7

What is the disadvantage if Copper cables?

Answer 7

Copper cables are susceptible to electrical interface and signal attenuation. This can limit the distance between devices and the speed of data transfers.

Question 8

What are the advantages of Fibre Cables?

Answer 8

1. Less susceptible to electrical interference and are also less lossy than copper.
2. Can be used in very high-speed systems, 10Gbps over long communication links often spanning many kilometers.

Question 9

What are the disadvantages of Fibre cables?

Answer 9

1. More expensive than copper because they require specialist equipment and connectors to make clean and efficient connections.
2. Most electronic systems are copper based and expensive conversion systems are required.

Question 10

What is the advantage of wireless systems?

Answer 10

Free to air and less expensive than copper and fibre systems.

Question 11

What are the disadvantages of Wireless systems?

Answer 11

1. Susceptible to interface and limited bandwith.
2. Signal jamming is a serious concern, causing denial-of-service by polluting the airwaves with interference and blocking the reception of transmitted data.

Question 12

What is Signal Propagation?

Answer 12

The time for a signal pulse to travel between devices.

Question 13

How fast is Signal Propagation in Fibre Optic Cables?

Answer 13

Speed of light.

Question 14

What is Signal Reflection?

Answer 14

When a pulse meets a connector, joint, sharp-bend or end point, part of the energy signal is reflected back to its source.

Question 15

What is the effect of ‘ringing’ in regards to signal reflection?

Answer 15

Ringing can cause serious bit errors in the received data.

Question 16

What is Signal Attenuation?

Answer 16

Energy is lost as a signal propagates along wire, fibre optic or air. The signal gets smaller as the distance from the originating source increases.

Question 17

What is Packet Switching?

Answer 17

a mode of data transmission in which a message is broken into a number of parts which are sent independently, over whatever route is optimum for each packet, and reassembled at the destination.

Question 18

What are the two types of network addresses?

Answer 18

MAC address (Physical) and IP Address (Logical).

Question 19

What are the characteristics of LANs (Local Area Networks)

Answer 19

Confined to a limited geographical area. Typically owned, controlled and managed from within an organisation by a specialised administrator.

Question 20

What are the characteristics of WANs (Wide Area Network)

Answer 20

Large Geographical area, connects Local Area Networks together. Distibuted ownership and management and are not owned by any one organisation.

Question 21

Name the advantages of Peer-to-Peer Networks

Answer 21

1. Simple to setup.
2. Don’t require specialist servers.
3. Simple to administer and do not require a network administrator.

Question 22

Name the disadvantages of Peer-to-Peer Networks

Answer 22

1. No Centralised administraion or security.
2. Processing security only on a machine by machine basis.
3. Processing / loading on devices can become excessive.

Question 23

What are the advantages of the Client-Server model?

Answer 23

1. Simplifies network administration
2. Easier to scale.
3. Centralises user accounts, security, and access controls.