30 Questions
What happens when two bits in one data unit are damaged and two bits in the same positions in another data unit are also damaged?
The LRC checker does not detect an error.
What type of parity is used for the LRC?
Even parity
What is the binary representation of the LRC for the message 'THE CAT'?
00101111
What is the purpose of the LRC checker?
To detect errors in transmission
What is the approximate percentage of transmission errors detected by CRC?
99.999%
What is the purpose of the CRC?
To detect transmission errors
If data is sent at a rate of 1Mbps, how many bits can a noise of 1/100 sec affect?
10,000 bits
What is the primary purpose of error detection in data communications?
To decide whether the received data is correct or not
What type of redundancy checking is also referred to as character parity?
Vertical redundancy checking (VRC)
What is the main advantage of using longitudinal redundancy checking (LRC)?
It increases the likelihood of detecting burst errors
What happens to the LRC bits in the transmitter?
They are computed and appended to the end of the message
What type of error can VRC detect, but only if the total number of errors is odd?
Burst error
What is the purpose of the checksum in error detection?
To detect errors involving an odd number of bits
What is the process of creating a checksum?
Adding sections together using one's complement and then complementing the sum
What is the primary requirement for reliable communication in networks?
Data transmission with complete accuracy
What is the function of the generator polynomial in CRC?
To create a checksum for error detection
Which type of error is most likely to occur in serial data transmission?
Burst error
What operation is performed on the data and generator polynomial in CRC?
Modulo-2 division
What is the purpose of the CRC code?
To detect errors in transmission
What is the duration of a bit in serial data transmission at a rate of 1Mbps?
1 μs
Which layer of the OSI model is responsible for error detection and correction?
Data link layer and transport layer
What type of errors can the checksum detect?
Most errors involving an even number of bits and all errors involving an odd number of bits
What is the term for two or more bits in the data unit changing from 1 to 0 or from 0 to 1?
Burst error
Why is single-bit error less likely to occur in serial data transmission?
The noise must have a very short duration
What is the primary advantage of using forward error correction over retransmission?
It is faster and more efficient.
What is the condition that must be satisfied by the value of r in error correction?
2r ≥ m+r+1
How does the receiver correct a single-bit error using an error-correcting code?
It reverses the value of the altered bit.
What is the purpose of redundancy bits in error correction?
To enable error detection and correction.
What type of error can be corrected using a Hamming code?
Single-bit error.
What is the benefit of using a Hamming code for error detection?
It can detect and correct single-bit errors.
This quiz covers the basics of error detection and correction in computer networks, including types of errors and correction methods.
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