12. - acehsc.net · in october 2006, the rock band wolfmother streamed the first live show to...

Communication systems multiple choice questions 1. If communication traffic can travel in both directions, but only one way at a time, the communication system is

said to be A. half duplex B. full duplex C. nil duplex D. less duplex

2. Morgan sends a video file to a web-based video hosting site. What best describes Morgan’s action?

A. Uploading B. Handshaking C. Downloading D. Videoconferencing

3. A device that interconnects two networks that use similar protocols is known as a

A. Router B. Bridge C. Gateway D. Nibble

4. A protocol

A. is an agreed procedure for establishing and maintaining communication between two computer devices B. is something that happens when a handshake occurs C. takes the place of a handshake D. has nothing to do with communications

5. Which error detection method is the most accurate?

A. cyclical redundancy check B. check sum C. block character check D. parity bit

6. A modem that can operate at 28000 baud can

A. Throughput data at a maximum speed of 28000 bps B. Throughput data at a maximum speed of 56000 bps C. Operate 28000 signal changes per second D. Operate 56000 signal changes per second

7. The Internet is a

A. large supercomputer controlling all information B. handful of supercomputers controlling all the information C. global network of communication links to which any user with a computer, and ISP account can link D. network within a local area

8. 9. What is ‘smtp’?

a. communications protocol used for receiving files sent from one computer to another over a network b. an internet standard for sending email messages from one computer to a server over a network c. an internet standard for securing email messages from one computer to a server over a network d. a protocol used for sending secure webpages and webpage components over the internet

10. A network configuration that has four nodes connected to a central server via a single linear cable whose two

ends to not meet is called a a. bus network b. star network c. ring topology d. hybrid topology

11. 12.

15. In October 2006, the rock band Wolfmother streamed the first live show to mobile phones. The show was encoded and compressed, then uploaded to a web server. A journalist reported that during fast sections of the guitar, the audio was distorted and broken. What would most likely have caused this distortion?

A. the speed of the server B. electromagnetic interference C. limitations of mobile bandwidth D. limitations of the speakers in mobile phones

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IPT Trial HSC 2010 Suggested Answers and Marking Criteria

Page 4 of 18

Question 23 (a)

Marking C riter ia Marks

Outlines at least THREE different relevant functions 3

Outlines TWO different relevant functions 2

Outlines ONE relevant function OR identifies THREE functions 1

ADSL router includes the functions of an ADSL modem, a router and an Ethernet switch (or possibly hub). The ADSL modem function modulates data packets travelling out so they comply with the protocols used by ADSL and performs the reverse operation to demodulate data packets as they arrive over the ADSL line into digital signals. ADSL uses standard copper phone lines, however it utilises frequencies above those used for voice. Secondly the router function uses IP to direct network packets to both LAN nodes and more critically to nodes on the Internet. Most routers also provide a variety of other functions, including firewalls and other security features. The Ethernet switch (or possibly hub) connects nodes using the transmission level Ethernet protocol. In this case the switch has 4 ports therefore up to four nodes can be directly connected. The switch and the connected nodes form a LAN where the switch directs data packets to their destination node based on

-in MAC address. If it is a hub then all packets are sent to all nodes.

Question 23 (b)


Demonstrates good understanding of the new hardware required 2

Demonstrates limited understanding of the function of new hardware required 1

To enable wireless connections a wireless access point (WAP) is required. The WAP converts Ethernet to wireless 802.11g so the laptops can connect. However, for home use it is often more cost effective to purchase a wireless router (which includes a built-model that includes a WAP. If a wireless router is purchased then all additional functions should be turned off (refer to user manual) so the device acts just as a WAP would. The WAP should be connected to one of the spare Ethernet ports . This will enable wireless devices (the laptops) to join the Ethernet network via the 802.11g wireless link, and then connect to the Internet via the ADSL link. If a new

In all cases security should be setup for the 802.11g network to prevent others from accessing the network.

Question 23 (c)


Demonstrates excellent understanding of the network including all hardware devices and links required, with a correctly labelled diagram including correct transmission level protocols

3

Demonstrates sound understanding of the network including most hardware devices and links 2

Demonstrates some limited understanding of the network 1

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IPT Trial HSC 2010 Suggested Answers and Marking Criteria

Page 5 of 18

Question 23 (d)


Identifies HTTP and TCP/IP protocols AND demonstrates excellent understanding of the essential processes each performs.

3

Identifies HTTP and TCP/IP protocols AND demonstrates general understanding of the essential processes each performs.

2

Identifies HTTP and TCP/IP protocols OR demonstrates general understanding of the role of the application level, and the communication, control and addressing level protocols

1

HTTP GET command with the URL of the webpage. When the HTTP command reaches the web server the web server responds by

r, which makes sense of the file and displays it within the browser. At the communication, control and addressing level TCP/IP operates to manage the delivery of the data packets involved in the transfer of the HTTP GET command and the transfer of the web page document back to the browser. TCP ensures messages reach their destination correctly, while IP manages the actual delivery through the network. Although TCP and IP operate together, each performs distinct functions. A TCP communication session is initiated between sender and receiver. All TCP segments are sent

acknowledges receipt of each segment as they are received. If an acknowledgement is not received within a reasonable amount of time then the sender will retransmit that segment. The IP manages the movement of data packets (datagrams) from sender to receiver. The IP address is used by routers to determine the most efficient route each datagram should follow. IP does not guarantee delivery of datagrams - in fact, datagrams found to have an error or other problem are simply discarded.

Question 24 (a)


All entities and processes are identified 1

External Entities: Sending User, Receiving User Processes: Encrypt message, Generate keys, Decrypt message

Question 24 (b)


Demonstrates excellent understanding of the encryption, transfer and decryption process shown in the diagram, including the generation and use of the two keys

3

Demonstrates excellent understanding of at least two significant processes comprising the encryption, transfer and decryption process shown in the diagram

2

Demonstrates limited understanding of at least one process shown in the diagram 1

1. Sending user constructs the message 2. Sender requests public key 3. Receiver generates a public/private key pair and sends the public key to the sender. 4. Sender uses the public key to encrypt the message to be sent 5. Encrypted message is transmitted from sender to receiver 6. The receiver uses the private key to decrypt the message 7. Message is viewed by receiving user

Answer 3

Answer 4

12. - acehsc.net · in october 2006, the rock band wolfmother streamed the first live show to...

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