6.2 SecurityPrivacy&DataIntegrity.data_integrity

Question 1

What is data integrity?

Answer 1

Data integrity refers to the accuracy, completeness, and consistency of data.

Question 2

How can data integrity be compromised?

Answer 2

• During data entry and data transmission.
• By malicious attacks like malware or hacking.
• Through accidental data loss from hardware issues.

Question 3

What are two methods used to ensure data integrity?

Answer 3

Validation and verification.

Question 4

What is validation?

Answer 4

A method used to ensure entered data is reasonable and meets specific input criteria.

Question 5

What is verification?

Answer 5

A method used to ensure data is correct, using techniques like double entry or visual checks.

Question 6

What is a check digit?

Answer 6

An additional digit appended to a number to verify if the entered data is error-free.

Question 7

How is a check digit calculated using Modulo-11?

Answer 7

By applying modulus division by 11 to determine the check digit.

Question 8

What is a checksum?

Answer 8

A verification method used to detect if data has been altered or corrupted during transfer, calculated from the data block being sent.

Question 9

What is a parity check?

Answer 9

A method for verifying if data was transferred correctly, using even or odd parity.

Question 10

What is a parity bit?

Answer 10

An extra bit added at the end of a byte to maintain the correct parity according to the sender/receiver’s protocol.

Question 11

What is a parity block?

Answer 11

A combination of horizontal and vertical parity checks used on a block of data during transfer.

Question 12

How can you mitigate risks to data integrity?

Answer 12

• Use validation and verification during data entry.
• Protect systems against malware and hacking.
• Implement regular data back-ups to prevent accidental data loss.

Question 13

What is a parity byte?

Answer 13

A parity byte is an additional byte sent with transmitted data to enable vertical parity checking, alongside horizontal parity checking.

Question 14

What is Automatic Repeat Request (ARQ)?

Answer 14

ARQ is a type of verification check used to ensure data is received correctly.

Question 15

What is an acknowledgement in data transmission?

Answer 15

A message sent to the sender to confirm that data has been received without error.

Question 16

What is validation?

Answer 16

A method of checking if entered data is reasonable and within given criteria, but it does not confirm if the data is accurate or correct.

Question 17

Can validation detect accurate data entry mistakes?

Answer 17

No, validation checks if data is reasonable, but it cannot verify its accuracy (e.g., entering age as 62 instead of 26 would pass validation).

Question 18

What are common types of validation tests?

9

Answer 18

• Type check: Ensures data is of the correct type (e.g., numbers only in numeric fields).
• Range check: Ensures data falls within specified limits.
• Format check: Ensures data matches a required format (e.g., date format).
• Length check: Ensures data has the required number of characters.
• Presence check: Ensures mandatory fields are not left empty.
• Existence check: Ensures referenced data or files actually exist.
• Limit check: Checks either the upper or lower limit (but not both).
• Consistency check: Ensures related fields have logically consistent data.
• Uniqueness check: Ensures entered data is unique (e.g., usernames).

Question 19

Give an example of a type check validation.

Answer 19

Entering “sk.34” in a price field would fail, but entering “34.50” would pass.

Question 20

What is a range check, and give an example.

Answer 20

It checks if data falls within set limits. Example: Entering age as “-120” fails; “48” passes.

Question 21

Provide an example of a format check validation.

Answer 21

Entering a date as “12-12-20” fails if the format is “dd/mm/yyyy”, while “12/12/2020” passes.

Question 22

What is a length check with an example?

Answer 22

It verifies if data meets required length. Example: A phone number “012 345 678” fails if 11 digits are needed, while “012 345 678 90” passes.

Question 23

What is a presence check with an example?

Answer 23

Ensures required fields are filled. Example: Leaving a passport number field empty fails, while “AB 1234567 CD” passes.

Question 24

What is an existence check with an example?

Answer 24

Verifies if data or a file exists. Example: Searching for non-existent car registration “A123BCD” fails, while finding “books_in_stock” in a database passes.

Question 25

What is a limit check with an example?

Answer 25

Checks data against a single limit. Example: Entering "-25" for age fails if negative values are not allowed; "72" passes if the upper limit is 140.

Question 26

What is a consistency check with an example?

Answer 26

Ensures data in related fields is logically consistent. Example: Selecting "Mr" as a title and "female" as gender fails; selecting "Ms" and "female" passes.

Question 27

What is a uniqueness check with an example?

Answer 27

Ensures data is unique. Example: Choosing "MAXIMUS222" fails if already taken; website name "Aristooo.com" passes if it's unused.

Question 28

What is verification in data entry?

Answer 28

Verification is a method of preventing errors when data is manually entered or transferred between computers.

Question 29

What are the three common methods of verification during data entry?

Answer 29

- **Double Entry:** Data is entered twice by two people and compared for discrepancies. - **Visual Check:** Data on the screen is compared with the original document to identify errors. - **Check Digits:** An additional digit is added to a number to detect errors during data entry.

Question 30

How does double entry verification work?

Answer 30

Data is entered twice, often by two different individuals, and the entries are compared to identify inconsistencies.

Question 31

What is a visual check in verification?

Answer 31

A manual comparison of the entered data with the original source document to ensure accuracy.

Question 32

What is a check digit?

Answer 32

An extra digit added to a number (usually at the end) to help detect errors like incorrect entries, transpositions, omissions, or phonetic mistakes.

Question 33

Where are check digits commonly used?

Answer 33

In barcodes, ISBNs (books), and VINs (vehicle identification numbers).

Question 34

What types of errors can check digits detect?

Answer 34

- **Incorrect digits:** e.g., entering 8190 instead of 8180. - **Transposition errors:** e.g., entering 8108 instead of 8180. - **Omitted or added digits:** e.g., entering 818 or 81180 instead of 8180. - **Phonetic errors:** e.g., entering 13 (thirteen) instead of 30 (thirty).

Question 35

What is the modulo-11 method for calculating check digits?

Answer 35

1. Assign weightings from 7 to 1 (left to right) to each digit in a 7-digit number. 2. Multiply each digit by its weighting and sum the results. 3. Divide the total by 11 and find the remainder. 4. Subtract the remainder from 11 to get the check digit (if the result is 10, 'X' is used).

Question 36

Can you provide an example of modulo-11 check digit calculation?

Answer 36

- Number: 4 1 5 6 7 1 0 - Weightings: 7, 6, 5, 4, 3, 2, 1 - Calculation: (7×4) + (6×1) + (5×5) + (4×6) + (3×7) + (2×1) + (1×0) = 106 - 106 ÷ 11 = 9 remainder 7 - 11 − 7 = 4 (check digit) - Final number: 4 1 5 6 7 1 0 **4** If an incorrect number like 4 1 5 7 6 1 0 4 is entered and it does not pass check digit verification. The recalculated check digit would be 3 instead of 4, indicating an error occurred during data entry.

Question 37

How does the check digit help detect errors?

Answer 37

When the number is re-entered, the check digit is recalculated. If the new check digit doesn't match the original, an error is detected.

Question 38

What is verification during data transfer?

Answer 38

Verification during data transfer ensures data is not corrupted or lost when sent electronically between devices.

Question 39

What are some common methods of verification during data transfer?

Answer 39

- **Checksums** - **Parity Checks** - **ARQ**

Question 40

What is a checksum?

Answer 40

A checksum is a value calculated from a block of data and sent along with the data to detect any changes or corruption during transmission.

Question 41

How is a checksum calculated?

Answer 41

1. Add all the byte values in the data block. 2. If the sum (X) is ≤ 255, the checksum equals this value. 3. If X > 255: - Divide X by 256: X / 256 - Round down the result to get Y. - Multiply Y by 256 to get Z. - Subtract Z from X: X - Z (this is the checksum).

Question 42

Example of checksum calculation:

Answer 42

- Sum of bytes (X) = 1185 - 1185 / 256 = 4.629 → Y = 4 (rounded down) - 4 times 256 = 1024 (Z) - 1185 - 1024 = 161 (checksum)

Question 43

How does a checksum detect errors?

Answer 43

The sender’s checksum is compared with the receiver’s recalculated checksum. If they differ, an error occurred, triggering a request to resend the data.

Question 44

What is a parity check?

Answer 44

A parity check uses a parity bit to detect errors in data transmission, ensuring the correct number of 1-bits based on even or odd parity.

Question 45

What is a parity bit?

Answer 45

An extra bit added to a byte before transmission to ensure the total number of 1-bits is even (even parity) or odd (odd parity).

Question 46

How does even parity work?

Answer 46

The parity bit is set so the total number of 1-bits is even. - Example: Data = 1 1 0 1 1 0 0 (4 ones → already even) - Parity bit = 0 → Final byte: 0 1 1 0 1 1 0 0

Question 47

How does odd parity work?

Answer 47

The parity bit is set so the total number of 1-bits is odd. - Example: Data = 1 1 0 1 1 0 0 (4 ones → even) - Parity bit = 1 → Final byte: 1 1 1 0 1 1 0 0

Question 48

How does a parity check detect errors?

Answer 48

After transmission, the receiver recalculates the parity. If it doesn't match the agreed parity (even/odd), an error is detected.

Question 49

Example of parity error detection:

Answer 49

- **Sender’s byte (even parity):** 0 1 0 1 1 1 0 0 (4 ones → even) - **Receiver’s byte:** 0 1 0 0 1 1 0 0 (3 ones → odd) - **Result:** Error detected because parity changed from even to odd.

Question 50

Can a parity check identify the exact bit in error?

Answer 50

No, it can detect that an error occurred but cannot specify which bit is incorrect.

Question 51

What is the method of parity blocks in error checking for transmitted data?

Answer 51

Parity blocks involve performing a parity check both horizontally and vertically on a block of data to identify and locate errors. The method uses a parity byte that indicates the result of the vertical parity check and marks the end of the data block.

Question 52

What does a parity byte represent in the parity block method?

Answer 52

The parity byte consists entirely of the parity bits from the vertical parity check of the data block and also indicates the end of the transmitted data block.

Question 53

When might it be impossible to locate an error using the parity block method?

Answer 53

It may be impossible to locate the error if an even number of bits change value during transmission, as this would not alter the overall parity in a way that helps identify the specific error.

Question 54

What is Automatic Repeat Request (ARQ) in error checking?

Answer 54

ARQ is a method that involves sending an acknowledgment message to confirm correct data receipt, and requesting a re-send if an error is detected, or if a timeout occurs before acknowledgment.

Question 55

How does ARQ work when no error is detected in transmitted data?

Answer 55

If no error is detected, a positive acknowledgment is sent to the sender to confirm that the data has been received correctly.

Question 56

What happens if an error is detected during data transmission using ARQ?

Answer 56

If an error is detected, the receiving device requests the sending device to re-send the data packet.

Question 57

How does ARQ handle timeouts?

Answer 57

If a timeout occurs (i.e., the acknowledgment is not received within a specified time), the sending device will re-send the data packet.

Question 58

What is the purpose of ARQ in mobile phone networks?

Answer 58

ARQ is used in mobile phone networks to ensure data integrity by managing errors and ensuring reliable transmission.