**Error Detection and Correction**.

#### Practice Exam Test Questions

**Choose the letter of the best answer in each questions.**

1. Checksums use _________ arithmetic.

A)ย ย one’s complement arithmetic

B)ย ย two’s complement arithmetic

C)ย ย either (a) or (b)

D)ย ย none of the above

Answer: **Option A**

Solution:

2. The checksum of 1111 and 1111 is _________.

A)ย ย 0000

B)ย ย 1111

C)ย ย 1110

D)ย ย 0111

Answer: **Option A**

Solution:

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

A)ย ย 1 to 10

B)ย ย 0 to 10

C)ย ย 1 to 11

D)ย ย none of the above

Answer: **Option B**

Solution:

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

A)ย ย one bit less than

B)ย ย one bit more than

C)ย ย The same size as

D)ย ย none of the above

Answer: **Option B**

Solution:

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

A)ย ย Hamming rule

B)ย ย Hamming code

C)ย ย Hamming distance

D)ย ย none of the above

Answer: **Option C**

Solution:

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

A)ย ย range

B)ย ย power

C)ย ย degree

D)ย ย none of the above

Answer: **Option C**

Solution:

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

A)ย ย addition and subtraction

B)ย ย addition and multiplication

C)ย ย addition and division

D)ย ย none of the above

Answer: **Option A**

Solution:

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

A)ย ย The quotient

B)ย ย The dividend

C)ย ย The divisor

D)ย ย The remainder

Answer: **Option D**

Solution:

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

A)ย ย CRC

B)ย ย Checksum

C)ย ย Simple parity check

D)ย ย Two-dimensional parity check

Answer: **Option C**

Solution:

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

A)ย ย block; blockwords

B)ย ย block; datawords

C)ย ย linear; datawords

D)ย ย none of the above

Answer: **Option B**

Solution:

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

A)ย ย burst

B)ย ย double-bit

C)ย ย single-bit

D)ย ย none of the above

Answer: **Option A**

Solution:

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

A)ย ย 0

B)ย ย 1

C)ย ย 2

D)ย ย none of the above

Answer: **Option A**

Solution:

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

A)ย ย onward

B)ย ย forward

C)ย ย backward

D)ย ย none of the above

Answer: **Option B**

Solution:

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

A)ย ย 5

B)ย ย 4

C)ย ย 3

D)ย ย none of the above

Answer: **Option C**

Solution:

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

A)ย ย an odd-number of

B)ย ย an even-number of

C)ย ย two

D)ย ย no errors

Answer: **Option A**

Solution:

16. The Hamming distance between equal codewords is _________.

A)ย ย 0

B)ย ย 1

C)ย ย n

D)ย ย none of the above

Answer: **Option A**

Solution:

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

A)ย ย ANDing

B)ย ย XORing

C)ย ย ORing

D)ย ย none of the above

Answer: **Option B**

Solution:

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

A)ย ย forward

B)ย ย backward

C)ย ย retransmission

D)ย ย none of the above

Answer: **Option C**

Solution:

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

A)ย ย linear; nonlinear

B)ย ย block; convolution

C)ย ย block; linear

D)ย ย none of the above

Answer: **Option B**

Solution:

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

A)ย ย 1 and 2

B)ย ย 0 and 1

C)ย ย 0 and 2

D)ย ย none of the above

Answer: **Option B**

Solution:

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

A)ย ย 11

B)ย ย 6

C)ย ย 5

D)ย ย none of the above

Answer: **Option A**

Solution:

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

A)ย ย detection; correction

B)ย ย correction; detection

C)ย ย creation; correction

D)ย ย creation; detection

Answer: **Option B**

Solution:

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

A)ย ย 4

B)ย ย 8

C)ย ย 2

D)ย ย none of the above

Answer: **Option A**

Solution:

24. The checksum of 0000 and 0000 is __________.

A)ย ย 0000

B)ย ย 1111

C)ย ย 0111

D)ย ย 1110

Answer: **Option B**

Solution:

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

A)ย ย 1101

B)ย ย 1000

C)ย ย 1111

D)ย ย none of the above

Answer: **Option B**

Solution:

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

A)ย ย 5

B)ย ย 3

C)ย ย 2

D)ย ย none of the above

Answer: **Option A**

Solution:

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

A)ย ย Checksum

B)ย ย CRC

C)ย ย Simple parity check

D)ย ย Two-dimensional parity check

Answer: **Option A**

Solution:

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

A)ย ย redundancy

B)ย ย degree

C)ย ย generator

D)ย ย none of the above

Answer: **Option C**

Solution:

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

A)ย ย OR

B)ย ย XOR

C)ย ย AND

D)ย ย none of the above

Answer: **Option B**

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)ย ย codewords

B)ย ย datawords

C)ย ย blockwords

D)ย ย none of the above

Answer: **Option A**

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)ย ย 11

B)ย ย 5

C)ย ย 6

D)ย ย none of the above

Answer: **Option C**

Solution:

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

A)ย ย x

B)ย ย 1

C)ย ย x + 1

D)ย ย none of the above

Answer: **Option C**

Solution:

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

A)ย ย Convolution

B)ย ย Cyclic

C)ย ย Non-linear

D)ย ย none of the above

Answer: **Option B**

Solution:

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

A)ย ย 0

B)ย ย 1

C)ย ย 2

D)ย ย none of the above

Answer: **Option C**

Solution:

#### Complete List of Chapter Quiz in Data Communications and Networking

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### MCQ in Error Detection and Correction (pdf)

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