Computer Networks - Data Communication & Network Security


Method of communication in which transmission takes place in both directions, but only in one direction at a time, is called




four wire circuit


full duplex


half duplex


Option: D

Explanation :

half-duplex (HDX) system provides communication in both directions, but only one direction at a time (not simultaneously). Typically, once a party begins receiving a signal, it must wait for the transmitter to stop transmitting, before replying (antennas are of trans-receiver type in these devices, so as to transmit and receive the signal as well).
full-duplex (FDX), or sometimes double-duplex system, allows communication in both directions, and, unlike half-duplex, allows this to happen simultaneously. Land-line telephone networks are full-duplex, since they allow both callers to speak and be heard at the same time, the transition from four to two wires being achieved by a hybrid coil. A good analogy for a full-duplex system would be a two-lane road with one lane for each direction.
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Unmodulated signal coming from a transmitter is known as

A. carrier signal
B. baseband signal
C. primary singal
D. None of these

Option: B

Explanation :


Bit stuffing refers to

A. inserting a '0' in user stream to differentiate it with a lag
B. inserting a '0' in lag stream to avoid ambiguity
C. appending a nibble to the lag sequence
D. appending a nibble to the use data stream

Option: A

Explanation :
Bit stuffing is required when there is a flag of bits to represent one of the incidents like start of frame, end of frame, etc, If same lag of bits appear in the data stream, a zero can be inserted. The receiver deletes this zero from the data stream.


 In a broad sense, a railway track is an example of

A. simplex
B. half-duplex
C. full-duplex
D. All of these

Option: B

Explanation :


Frequency range at which the land coaxial cables are used, is

A. 106 to 108 Hz
B. 1010 to 1011 Hz
C. 103 to 104 Hz
D. None of these

Option: A

Explanation :

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