In this section of Data Communication and Networking – Error Detection and Correction MCQ (Multiple choice) Based Short Questions and Answers,All the Multiple Choice Questions and Answers (MCQs) have been compiled from the book of Data Communication and Networking by The well known author behrouz forouzan.

**This Section covers below lists of topics.**

- Single-bit error or a burst error MCQs.
- Redundancy methods ,parity check, cyclic redundancy check (CRC), and checksum MCQs.
- Hamming code MCQs.

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

- block; blockwords
- linear; datawords
- block; datawords
- none of the above

C. block; datawords

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

- datawords
- blockwords
- codewords
- none of the above

C. codewords

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

- Hamming code
- Hamming distance
- Hamming rule
- none of the above

B. Hamming distance

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

- 5
- 6
- 11
- none of the above

B. 6

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

- 5
- 6
- 11
- none of the above

C. 11

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

- XORing
- ORing
- ANDing
- none of the above

A. XORing

#### 7. A simple parity-check code can detect __________ errors

- an even-number of
- two
- no errors
- an odd-number of

D. an odd-number of

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

- Non-linear
- Convolution
- Cyclic
- none of the above

C. Cyclic

#### 9. The _____of errors is more difficult than the ______

- correction; detection
- detection; correction
- creation; correction
- creation; detection

A. correction; detection

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

- 1 to 10
- 1 to 11
- 0 to 10
- none of the above

C. 0 to 10

#### 11. In modulo-2 arithmetic, we use only ______

- 1 and 2
- 0 and 2
- 0 and 1
- none of the above

C. 0 and 1

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

- 1
- 2
- 0
- none of the above

C. 0

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

- 8
- 4
- 2
- none of the above

B. 4

#### 14. The Hamming distance between equal codewords is _________

- 1
- n
- 0
- none of the above

C. 0

#### 15. The Hamming distance between 100 and 001 is ________

- 2
- 0
- 1
- none of the above

A. 2

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

- 2
- 3
- 5
- none of the above

C. 5

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

- 3
- 4
- 5
- none of the above

A. 3

#### 18. The _______ of a polynomial is the highest power in the polynomial

- range
- degree
- power
- none of the above

B. degree

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

- degree
- generator
- redundancy
- none of the above

B. generator

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

- x
- x + 1
- 1
- none of the above

B. x + 1

#### 21. Which error detection method uses one's complement arithmetic?

- Simple parity check
- Two-dimensional parity check
- CRC
- Checksum

D. Checksum

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

- Simple parity check
- Two-dimensional parity check
- CRC
- Checksum

A. Simple parity check

#### 23. In cyclic redundancy checking, what is the CRC?

- The divisor
- The quotient
- The dividend
- The remainder

D. The remainder

#### 24. In cyclic redundancy checking, the divisor is _______ the CRC

- The same size as
- one bit less than
- one bit more than
- none of the above

C. one bit more than

#### 25. A burst error means that two or more bits in the data unit have changed.

- double-bit
- burst
- single-bit
- none of the above

B. burst

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

- backward
- onward
- forward
- none of the above

C. forward

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

- backward
- retransmission
- forward
- none of the above

B. retransmission

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

- block; linear
- linear; nonlinear
- block; convolution
- none of the above

C. block; convolution

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

- addition and multiplication
- addition and division
- addition and subtraction
- none of the above

C. addition and subtraction

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

- XOR
- OR
- AND
- none of the above

A. XOR