Telephone systems may be classified as:
	
1. duplex and symmetrical.
2. simplex and symmetrical.
3. duplex and asymmetrical.
4. simplex and asymmetrical.

A network that provides a constant bandwidth for the complete duration of a message transfer is a:

1. packet switched network.
2. circuit switched network.
3. cell switched network.

A router:

 	
1. determines on which outgoing link a packet is to be forwarded.
2. forwards a packet to all outgoing links, except the link upon which the packet originated.
3. forwards a packet to all outgoing links.
4. forwards a packet to the next free outgoing link.

The Internet is an example of a:

 	
1. packet switched network.
2. cell switched network.
3. circuit switched network.

A data link between the head office of a financial organization and one of its branches runs continuously at 2.048 Mbps. Between the hours of 0900 and 1700 it is noted that there are 295 bits received in error. Determine the bit error rate.
1. 2 x 10-7
2. 5 x 10-9
3. 5 x 10-8
4. 2 x 10-10

The optical fibre trans-Atlantic cable TAT-14 includes a section from Bude, Cornwall to Tuckerton, New Jersey. Determine the propagation delay if the route length is 6,254 km.
 	
1. 312.7 ms.
2. 31.98 ms.
3. 3.198 ms.
4. 31.27 ms.

A file is downloaded to a home computer using a 56 kbps modem connected to an Internet Service Provider. If the download completes in 2 minutes, estimate the maximum size of data downloaded.
 	
1. 13.44 Mbit.
2. 6.72 Mbit.
3. 26.88 Mbit.
4. 336 Kbit.

Baseband transmission may be defined as the transmission of a signal over a link:
 	
1. by means of wires.
2. without any change in frequency.
3. at a different band of frequencies.
4. which is relatively short.

Skin effect may be described as:
(Note: more than one answer is correct.)
 	
1. a thin layer of electricity.
2. conduction of electricity through skin.
3. conduction restricted to a small central region of a conductor.
4. conduction restricted to the outer layer of a conductor.

A block of data consisting of 2048 bits is transmitted between two computers interconnected by 450 m of twisted-pair wire. If the transmission rate is 34 kbps determine a, the ratio of propagation delay to transmission delay.
 	
1. 3.76 x 10-6
2. 37.6 x 10-6
3. 3.76 x 10-3
4. 376 x 10-6

Asynchronous transmission may be defined as:
 	
1. communication where the receiver clock must be in exact synchronism with that of the transmitter.
2. communication where the receiver clock must be in approximate synchronism with that of the transmitter.
3. communication where receiver will operate satisfactorily, even if its clock frequency is appreciably different to that of the transmitter.

Synchronous transmission may be defined as:
 	
1. communication where the receiver will operate satisfactorily, even if its clock frequency is appreciably different to that of the transmitter.
2. communication where the receiver clock must be in approximate synchronism with that of the transmitter.
3. communication where the receiver clock is arranged to be in exact synchronism with that of the receiver.

Manchester encoding is principally designed to:
 	
1. increase the bandwidth of a signal transmitted on the medium.
2. have more than one symbol per bit period.
3. ensure that the line remains unbalanced.
4. ensure that a transition occurs in the centre of each bit period.

Is the following statement true of the Go-back-N error control strategy?
A transmitter may send up to N packets before it receives an acknowledgment.

1. True
2. False

A protocol data unit (PDU) is exchanged between the same layer in two separate protocol stacks. It comprises the PDU passed from the layer immediately above and its own protocol control information.

1. True
2. False