Chapter 17 Communication and Internet Technologies

Question 1

State the 5 requirements for a data communications system. (3)

Answer 1

1. Sender
2. Receiver
3. Transmission medium
4. A message (any type of transmitted data)
5. protocol

Question 2

A message can only be transmitted if there is an ______ ________

Answer 2

Agreed Protocol

Question 3

What does “Bandwidth” mean?

Answer 3

The amount of data that can be carried on a network in a given period of time.

Question 4

What does “Protocol” mean?

Answer 4

A set of rules that govern the sending and receiving of data.

Question 5

What does “Network topology” mean?

Answer 5

Describes how the devices on a network are connected together.

Question 6

What is a Bus Topology

Answer 6

Has one link but is shared by a number of end-systems (multi-point connection)

Question 7

What is a Star Topology

Answer 7

Each end-system has a point-to-point connection to a central device.

Question 8

Name 2 types of transmission modes

Answer 8

Circuit Switching & Packet Switching

Question 9

Describe what is meant by Circuit Switching

Answer 9

A dedicated channel is established for the duration of the connection.

Question 10

Give 3 features of a Star Topology

Answer 10

1. Central device
2. Each node connects to a central device
3. Each node has a dedicated connection

Question 11

Describe Packet Switching

Answer 11

Data is broken down into packets before it is transported. Data packets contain the IP address and sequencing info’, thus they can travel along any path. This allows them to find the fastest possible route.

Question 12

Circuit Switching Pros

Answer 12

. Whole bandwidth is available
. Data transfer rate is faster
. Packets arrive in the same order they were sent
. Data packets can’t be lost

Question 13

Circuit Switching Cons

Answer 13

. Not very flexible
. Nobody can use the circuit (channel)
. If there is a fault on the dedicated line, there is no
alternate route
. More expensive as dedicated channel require full
bandwidth

Question 14

Packet Switching Pros

Answer 14

. Can overcome faulty lines as packets are re-routed
. Less expensive (user only charged for duration of call)
. Higher data transmission

Question 15

Packet Switching Cons

Answer 15

. Time consuming if packet is lost - must be re-sent
. Does not work well for real-time data transmission
. There is a delay at destination as packets must be re-
assembled

Question 16

What does TCP stand for

Answer 16

Transmission Control Protocol

Question 17

What are the 4 layers of the TCP/IP model?

Answer 17

Application
Transport
Internet
Link

(remember ATIL acronym)

Question 18

Name protocols for each layer

Answer 18

Application - HTTP, SMTP, DNS, FTP, POP3
Transport - TCP, UDP, SCTP
Internet - IPv4, IPv6

Question 19

How is each layer of the stack implemented?

Answer 19

Sequentially

Question 20

Explain why circuit switching is used for voice calls? (2)

Answer 20

Because the whole bandwidth is available, which allows for faster data transmission, making it better for real-time conversations.

Question 21

Why is packet switching used to send and receive data? (2)

Answer 21

Less likely chance of data packet being lost as it can be re-sent.

Question 22

Network Interface Card (NIC)

Answer 22

Has a unique MAC address

Provides physical connection between router and a computer.

Question 23

Wireless Access Point (WAP)

Answer 23

Allows devices to connect via radio connection instead of using cable.

Question 24

What does “Peer-to-peer network” mean?

Answer 24

A network that doesn’t have any centralized servers. Each computer in the network can act as client and server.

Question 25

What protocol is used by P2P file sharing

Answer 25

Bit Torrent Protocol

Question 26

Bit Torrent allows for ____ ____ _____

Answer 26

Fast file share

Question 27

What is meant by “Tracker” in the BitTorrent protocol

Answer 27

A server that maintains a list of all the other peers actively downloading and uploading the content

Question 28

What is meant by “Seed” in the BitTorrent protocol

Answer 28

A peer computer that has 100% of the file

Question 29

What is meant by “Swarm” in the BitTorrent protocol

Answer 29

All of the connected peer computers that have part of the file to be downloaded