# Forouzan: MCQ in Error Detection and Correction

(Last Updated On: December 28, 2017)

This is the MCQ in Error Detection and Correction from book the Data Communications and Networking 4th Edition by Behrouz A. Forouzan. If you are looking for a reviewer in datacom, topic in Electronics Systems and Technologies (Communications Engineering) this will definitely help you before taking the Board Exam.

In this particular topic you have learned that Data can be corrupted during transmission. To address this issue some applications require that errors be detected and must be corrected. If you skip the summary visit Error Detection and Correction.

#### Begin and Good luck!

Choose the letter of the best answer in each questions.

1. Checksums use _________ arithmetic.

• A)   one’s complement arithmetic
• B)   two’s complement arithmetic
• C)   either (a) or (b)
• D)   none of the above

Solution:

2. The checksum of 1111 and 1111 is _________.

• A)   0000
• B)   1111
• C)   1110
• D)   0111

Solution:

3. In modulo-11 arithmetic, we use only the integers in the range ______, inclusive.

• A)   1 to 10
• B)   0 to 10
• C)   1 to 11
• D)   none of the above

Solution:

4. In cyclic redundancy checking, the divisor is _______ the CRC.

• A)   one bit less than
• B)   one bit more than
• C)   The same size as
• D)   none of the above

Solution:

5. The ________ between two words is the number of differences between corresponding bits.

• A)   Hamming rule
• B)   Hamming code
• C)   Hamming distance
• D)   none of the above

Solution:

6. The _______ of a polynomial is the highest power in the polynomial.

• A)   range
• B)   power
• C)   degree
• D)   none of the above

Solution:

7. In modulo-2 arithmetic, __________ give the same results.

• D)   none of the above

Solution:

8. In cyclic redundancy checking, what is the CRC?

• A)   The quotient
• B)   The dividend
• C)   The divisor
• D)   The remainder

Solution:

9. Which error detection method consists of just one redundant bit per data unit?

• A)   CRC
• B)   Checksum
• C)   Simple parity check
• D)   Two-dimensional parity check

Solution:

10. In _____ coding, we divide our message into blocks, each of k bits, called ___.

• A)   block; blockwords
• B)   block; datawords
• C)   linear; datawords
• D)   none of the above

Solution:

11. A _____ error means that two or more bits in the data unit have changed.

• A)   burst
• B)   double-bit
• C)   single-bit
• D)   none of the above

Solution:

12. Adding 1 and 1 in modulo-2 arithmetic results in _________.

• A)   0
• B)   1
• C)   2
• D)   none of the above

Solution:

13. In ________ error correction, the receiver corrects errors without requesting retransmission.

• A)   onward
• B)   forward
• C)   backward
• D)   none of the above

Solution:

14. If the Hamming distance between a dataword and the corresponding codeword is three, there are _____ bits in error.

• A)   5
• B)   4
• C)   3
• D)   none of the above

Solution:

15. A simple parity-check code can detect __________ errors.

• A)   an odd-number of
• B)   an even-number of
• C)   two
• D)   no errors

Solution:

16. The Hamming distance between equal codewords is _________.

• A)   0
• B)   1
• C)   n
• D)   none of the above

Solution:

17. In a linear block code, the _______ of any two valid codewords creates another valid codeword.

• A)   ANDing
• B)   XORing
• C)   ORing
• D)   none of the above

Solution:

18. In ________ error correction, the receiver asks the sender to send the data again.

• A)   forward
• B)   backward
• C)   retransmission
• D)   none of the above

Solution:

19. We can divide coding schemes into two broad categories: ________ and ______coding.

• A)   linear; nonlinear
• B)   block; convolution
• C)   block; linear
• D)   none of the above

Solution:

20. In modulo-2 arithmetic, we use only ______.

• A)   1 and 2
• B)   0 and 1
• C)   0 and 2
• D)   none of the above

Solution:

21. To guarantee correction of up to 5 errors in all cases, the minimum Hamming distance in a block code must be ________.

• A)   11
• B)   6
• C)   5
• D)   none of the above

Solution:

22. The _____of errors is more difficult than the ______.

• A)   detection; correction
• B)   correction; detection
• C)   creation; correction
• D)   creation; detection

Solution:

23. In block coding, if k = 2 and n = 3, we have _______ invalid codewords.

• A)   4
• B)   8
• C)   2
• D)   none of the above

Solution:

24. The checksum of 0000 and 0000 is __________.

• A)   0000
• B)   1111
• C)   0111
• D)   1110

Solution:

25. In one’s complement arithmetic, if positive 7 is 0111, then negative 7 is ________.

• A)   1101
• B)   1000
• C)   1111
• D)   none of the above

Solution:

26. In block coding, if n = 5, the maximum Hamming distance between two codewords is ________.

• A)   5
• B)   3
• C)   2
• D)   none of the above

Solution:

27. Which error detection method uses one’s complement arithmetic?

• A)   Checksum
• B)   CRC
• C)   Simple parity check
• D)   Two-dimensional parity check

Solution:

28. The divisor in a cyclic code is normally called the _________.

• A)   redundancy
• B)   degree
• C)   generator
• D)   none of the above

Solution:

29. In modulo-2 arithmetic, we use the ______ operation for both addition and subtraction.

• A)   OR
• B)   XOR
• C)   AND
• D)   none of the above

Solution:

30. We add r redundant bits to each block to make the length n = k + r. The resulting n-bit blocks are called _________.

• A)   codewords
• B)   datawords
• C)   blockwords
• D)   none of the above

Solution:

31. To guarantee the detection of up to 5 errors in all cases, the minimum Hamming distance in a block code must be _______.

• A)   11
• B)   5
• C)   6
• D)   none of the above

Solution:

32. A generator that contains a factor of ____ can detect all odd-numbered errors.

• A)   x
• B)   1
• C)   x + 1
• D)   none of the above

Solution:

33. _______codes are special linear block codes with one extra property. If a codeword is rotated, the result is another codeword.

• A)   Convolution
• B)   Cyclic
• C)   Non-linear
• D)   none of the above

Solution:

34. The Hamming distance between 100 and 001 is ________.

• A)   0
• B)   1
• C)   2
• D)   none of the above

Solution: