Computer Network Questions and Answers

Q: The binary number 1101 is equivalent to which decimal value?

Correct answer: 13Each binary digit carries a place value that is a power of two, read from the right: \( 2^{0}, 2^{1}, 2^{2}, 2^{3} \), that is 1, 2, 4 and 8. For 1101 the set bits are in the 8, 4 and 1 positions: \[ 1\times8 + 1\times4 + 0\times2 + 1\times1 = 8 + 4 + 1 = 13. \] The reverse conversion divides repeatedly by two and reads the remainders upward: 13 gives remainder 1, then 6 gives 0, then 3 gives 1, then 1 gives 1 - reading up, 1101. It is worth memorising the first few powers of two, since almost every question in this area rests on them: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024. Note also that 1101 is D in hexadecimal, since one hexadecimal digit covers exactly four bits - which is why hexadecimal is used as shorthand for binary.

Q: How many digits of the network user Address are known as the DNIC (Data Network Identiication Code) ?

Correct answer: First fourThe DNIC is the first four digits of an X.121 network user address: three for the country and one to identify the network within it.

Q: Parity is used in data transmission to

Correct answer: detect single-bit errorsA parity bit is an extra bit appended to a group of data bits so that the total number of 1s is even, in even parity, or odd, in odd parity. The receiver recomputes it and compares. It detects a single-bit error but cannot correct it, because it shows that something is wrong without indicating which bit. And it fails entirely on an even number of errors, since two flipped bits leave the parity unchanged - which is its principal limitation. It is generated in hardware by a cascade of XOR gates, whose output is 1 exactly when the number of 1s is odd. Stronger schemes exist for more demanding work. Hamming codes use several parity bits over overlapping groups and can locate and correct a single-bit error. Cyclic redundancy checks detect burst errors far more reliably and are what network frames and storage media actually use. Parity survives in memory modules and serial links, where it is cheap and usually sufficient.

Q: In a crossbar with 1000 crosspoints, how many statistically are in use at any time ?

Correct answer: 250Crossbars are dimensioned on the observation that only about a quarter of the crosspoints are needed at once, since not every input is active and each active one uses a single crosspoint. For 1000 crosspoints that is 250.

Q: A decoder with 3 input lines has how many output lines?

Correct answer: 8A decoder activates exactly one output for each combination of its inputs, so \( n \) input lines give \( 2^{n} \) outputs. With three inputs that is \[ 2^{3} = 8. \] Such a device is called a 3-to-8 decoder. Its principal use is address decoding: the address lines of a processor are fed to a decoder whose outputs act as chip-select signals, so that exactly one memory or peripheral device responds to any given address. Decoders usually have an enable input, which allows several to be cascaded to decode a larger address space. The inverse device is an encoder, which takes \( 2^{n} \) inputs and produces an \( n \)-bit code. A priority encoder resolves the case of several inputs being active at once by responding to the highest, which is how interrupt controllers work. A related device is the seven-segment decoder, which converts a four-bit BCD digit into the seven signals that drive a display.

Q: Which among the following is not a transmission medium?

Correct answer: modemTelephone lines, coaxial cable and microwave systems all carry the signal, so each is a transmission medium. A modem is equipment at the end of the medium, converting the signal so it can travel.

Q: What is the decimal equivalent of the hexadecimal number 2F ?

Correct answer: 47In hexadecimal the digit F stands for 15, so \(2F_{16} = 2 \times 16 + 15 = 47\). Hexadecimal is convenient because each digit maps onto exactly four binary bits.

Q: Ether LAN uses

Correct answer: manchester encodingEthernet uses Manchester encoding: each bit is sent as a transition in the middle of its interval, so the receiver recovers the clock from the data itself and no separate timing signal is needed. The price is twice the bandwidth.

Q: Which of the given below houses the switches in Token Ring ?

Correct answer: MAUThe Multistation Access Unit holds the relays that close the ring: a station's connection is switched in when it is powered and bypassed when it is not, so one dead station does not break the ring.

101.

The binary number 1101 is equivalent to which decimal value?

A.13
B.11
C.15
D.12

Answer: B

Correct answer: 13

Each binary digit carries a place value that is a power of two, read from the right: \( 2^{0}, 2^{1}, 2^{2}, 2^{3} \), that is 1, 2, 4 and 8. For 1101 the set bits are in the 8, 4 and 1 positions: \[ 1\times8 + 1\times4 + 0\times2 + 1\times1 = 8 + 4 + 1 = 13. \] The reverse conversion divides repeatedly by two and reads the remainders upward: 13 gives remainder 1, then 6 gives 0, then 3 gives 1, then 1 gives 1 - reading up, 1101. It is worth memorising the first few powers of two, since almost every question in this area rests on them: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024. Note also that 1101 is D in hexadecimal, since one hexadecimal digit covers exactly four bits - which is why hexadecimal is used as shorthand for binary.

Discuss in Forum

102.

How many digits of the network user Address are known as the DNIC (Data Network Identiication Code) ?

A.First three
B.First four
C.First five
D.First seven

Answer: B

Correct answer: First four

The DNIC is the first four digits of an X.121 network user address: three for the country and one to identify the network within it.

Discuss in Forum

103.

Parity is used in data transmission to

A.detect single-bit errors
B.correct any number of errors
C.compress the data
D.encrypt the data

Answer: C

Correct answer: detect single-bit errors

A parity bit is an extra bit appended to a group of data bits so that the total number of 1s is even, in even parity, or odd, in odd parity. The receiver recomputes it and compares. It detects a single-bit error but cannot correct it, because it shows that something is wrong without indicating which bit. And it fails entirely on an even number of errors, since two flipped bits leave the parity unchanged - which is its principal limitation. It is generated in hardware by a cascade of XOR gates, whose output is 1 exactly when the number of 1s is odd. Stronger schemes exist for more demanding work. Hamming codes use several parity bits over overlapping groups and can locate and correct a single-bit error. Cyclic redundancy checks detect burst errors far more reliably and are what network frames and storage media actually use. Parity survives in memory modules and serial links, where it is cheap and usually sufficient.

Discuss in Forum

104.

Two networks each provide reliable connection-oriented service. One of them offers a reliable byte stream and the other offers a reliable message stream. A process writes 1024 bytes, then

A.both networks will receive 2048 bytes as a single unit
B.message stream network will receive 1024 bytes only at one time. But byte stream network will receive 2048 bytes as a single unit.
C.message stream network receives 2048 bytes as a whole. But bytes stream 1024 bytes only at a time.
D.both will receive 1024 bytes at one time since there is a gap between writes

Answer: B

Correct answer: message stream network will receive 1024 bytes only at one time

A message stream preserves the boundaries the sender wrote, so two writes of 1024 bytes arrive as two separate messages. A byte stream keeps no boundaries at all, so the same two writes may be read as one block of 2048 bytes, or in any other division.

Discuss in Forum

105.

In a crossbar with 1000 crosspoints, how many statistically are in use at any time ?

A.100
B.250
C.500
D.1000

Answer: B

Correct answer: 250

Crossbars are dimensioned on the observation that only about a quarter of the crosspoints are needed at once, since not every input is active and each active one uses a single crosspoint. For 1000 crosspoints that is 250.

Discuss in Forum

106.

A decoder with 3 input lines has how many output lines?

A.8
B.3
C.6
D.16

Answer: D

Correct answer: 8

A decoder activates exactly one output for each combination of its inputs, so \( n \) input lines give \( 2^{n} \) outputs. With three inputs that is \[ 2^{3} = 8. \] Such a device is called a 3-to-8 decoder. Its principal use is address decoding: the address lines of a processor are fed to a decoder whose outputs act as chip-select signals, so that exactly one memory or peripheral device responds to any given address. Decoders usually have an enable input, which allows several to be cascaded to decode a larger address space. The inverse device is an encoder, which takes \( 2^{n} \) inputs and produces an \( n \)-bit code. A priority encoder resolves the case of several inputs being active at once by responding to the highest, which is how interrupt controllers work. A related device is the seven-segment decoder, which converts a four-bit BCD digit into the seven signals that drive a display.

Discuss in Forum

107.

Which among the following is not a transmission medium?

A.telephone lines
B.coaxial cables
C.modem
D.microwave systems

Answer: C

Correct answer: modem

Telephone lines, coaxial cable and microwave systems all carry the signal, so each is a transmission medium. A modem is equipment at the end of the medium, converting the signal so it can travel.

Discuss in Forum

108.

What is the decimal equivalent of the hexadecimal number 2F ?

A.31
B.47
C.62
D.79

Answer: B

Correct answer: 47

In hexadecimal the digit F stands for 15, so \(2F_{16} = 2 \times 16 + 15 = 47\). Hexadecimal is convenient because each digit maps onto exactly four binary bits.

Discuss in Forum

109.

Ether LAN uses

A.polar encoding
B.diferential manchester encoding
C.manchester encoding
D.NRZ

Answer: C

Correct answer: manchester encoding

Ethernet uses Manchester encoding: each bit is sent as a transition in the middle of its interval, so the receiver recovers the clock from the data itself and no separate timing signal is needed. The price is twice the bandwidth.

Discuss in Forum

110.

Which of the given below houses the switches in Token Ring ?

A.NIC
B.MAU
C.Nine-pin connector
D.Transceiver

Answer: B

Correct answer: MAU

The Multistation Access Unit holds the relays that close the ring: a station's connection is switched in when it is powered and bypassed when it is not, so one dead station does not break the ring.

Discuss in Forum

Loading…

Topics

Other Subjects

Tags: Computer Network Questions and Answers || Computer Network MCQ Questions and Answers || Computer Network GK Questions and Answers || Computer Network GK MCQ Questions || Computer Network Multiple Choice Questions and Answers || Computer Network GK || GK on Computer Network || Computer Awareness Questions and Answers || Computer Awareness MCQ Questions and Answers || Computer Awareness GK Questions and Answers || GK on Computer Awareness

Computer Network Questions and Answers

Topics

Other Subjects

About Us

Stay informed about all important Dates & Notifications