Working of the WAN generally involves
Answer: D
Correct answer: All of these
A wide area network spans distances no single medium covers economically, so it uses whatever is available: leased telephone lines, terrestrial microwave links and satellite hops.
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Different computers are connected to a LAN by a cable and
Answer: B
Correct answer: interface card
Every machine on a LAN needs a network interface card to put frames on the cable and take them off. A modem is for telephone lines, which is a wide-area connection.
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The modem is used in data transmission. When was it invented, and in which country?
Answer: C
Correct answer: 1950, USA
Modems were developed in the United States in the 1950s, for the SAGE air defence system, which needed to carry radar data over telephone lines.
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Fibre optics have maximum segment
Answer: D
Correct answer: 2000 m
Fibre carries a signal furthest of the media in the list - 2000 m per segment for the 100Base-FX and 10Base-FL standards - because glass attenuates light far less than copper attenuates a current.
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Twisted pair have maximum segment of
Answer: C
Correct answer: 100 m
A twisted pair segment is limited to 100 m, which is why structured cabling is planned around that figure: 90 m of fixed cable and 10 m of patch leads.
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Thick coax have maximum segment of
Answer: A
Correct answer: 500 m
Thick coaxial cable, the 10Base5 of the original Ethernet, allows a 500 m segment - the 5 in the name records it. Thin coax, 10Base2, manages about 185 m.
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Method of communication in which transmission takes place in both directions, but only in one direction at a time, is called
Answer: D
Correct answer: half duplex
Half duplex allows both directions but only one at a time, so the line must be turned round between transmissions. Full duplex allows both at once and simplex only one direction ever.
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Unmodulated signal coming from a transmitter is known as
Answer: B
Correct answer: baseband signal
The signal as it comes from the source, before it is modulated onto a carrier, is the baseband signal. The carrier is what it is later imposed on.
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Bit stuffing refers to
Answer: A
Correct answer: inserting a '0' in user stream to differentiate it with a flag
The flag that marks a frame boundary is a fixed bit pattern, so the sender inserts a 0 after five consecutive 1s in the data, ensuring the pattern can never appear by accident. The receiver removes the inserted bit, so the data is unchanged.
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In a broad sense, a railway track is an example of
Answer: B
Correct answer: half-duplex
A single track carries trains in both directions but only one at a time, which is exactly half duplex. A double track would be full duplex.
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