What data integrity means in transmission

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Quick Questions

Shade in the A or B circle for each question.

1. Which statement describes data integrity?

A Data travels across the network as fast as possible

B Data arrives complete and correct, the same as what was sent

2. A photo is sent as 10 packets but only 9 arrive. What is wrong with its integrity?

A It is not complete because data is missing

B It is still complete because most of it arrived

3. A message says 'MEET AT 4' but arrives as 'MEET AT 5'. Which part of integrity failed?

A Correct, because the data was changed

B Complete, because the message is shorter

4. Data arrives with extra bits that the sender never sent. Does it have integrity?

A Yes, because more data is always better

B No, because extra data means it is not complete and correct

5. Which one helps protect data integrity during transmission?

A A protocol that checks the data and asks for a resend if needed

B A louder speaker on the sending device

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1sent: HELLO received: HELLO		AThe extra letter S means data was gained, so the data is not complete and integrity is lost.
2sent: HELLO received: HELO		Bsent: 1011 received: 1011
3Correct data means nothing was changed in transit, so each character still matches what was sent		COne bit changed from 1 to 0, so the data is not correct and integrity is lost.
4Protocols protect integrity by adding checks, such as a parity bit, that help spot damaged data		Ddata = 1011 + parity bit 1
5sent: CAT received: CATS -> integrity kept		EThe data has integrity: it arrived complete and correct, exactly as it was sent
6sent: 1100 received: 1000 -> integrity kept		FIntegrity is lost: the data is not complete because a letter went missing

Definitions

data integrity

Fill in the Blanks

Complete each line of code by filling in the missing parts.

sent ← "HELLO" received ← "HELLO" IF received _ sent THEN integrity ← TRUE

sentNum ← 5 gotNum ← 4 IF gotNum _ sentNum THEN missing ← TRUE

sent ← "1011" received ← "1001" IF received _ sent THEN changed ← TRUE

sentNum ← 5 gotNum ← 6 IF gotNum _ sentNum THEN extra ← TRUE

IF received = sent THEN OUTPUT "Intact" ____ OUTPUT "Resend needed" ENDIF

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A sent ← 'HELLO'

B received ← sent

C IF received = sent THEN

D OUTPUT 'Data is intact'

Question 2

A sent ← 5

B got ← 4

C IF got < sent THEN

D OUTPUT 'Data has extra'

Question 3

A sent ← 'DOG'

B received ← 'DOT'

C IF received ≠ sent THEN

D OUTPUT 'Data is missing'

Question 4

A complete ← TRUE

B correct ← TRUE

C IF complete OR correct THEN

D OUTPUT 'Integrity kept'

Question 5

A protocol ← 'JPEG'

B SEND data USING protocol

C RESEND packet IF missing

D OUTPUT 'Data arrives intact'

Answer Key

What data integrity means in transmission

Section A: Quick Questions

B — Data arrives complete and correct, the same as what was sent

A — It is not complete because data is missing

A — Correct, because the data was changed

B — No, because extra data means it is not complete and correct

A — A protocol that checks the data and asks for a resend if needed

Section B: Match the Pairs

sent: HELLO received: HELLO → The data has integrity: it arrived complete and correct, exactly as it was sent

sent: HELLO received: HELO → Integrity is lost: the data is not complete because a letter went missing

Correct data means nothing was changed in transit, so each character still matches what was sent → sent: 1011 received: 1011

Protocols protect integrity by adding checks, such as a parity bit, that help spot damaged data → data = 1011 + parity bit 1

sent: CAT received: CATS -> integrity kept → The extra letter S means data was gained, so the data is not complete and integrity is lost.

sent: 1100 received: 1000 -> integrity kept → One bit changed from 1 to 0, so the data is not correct and integrity is lost.

Section C: Definitions

data integrity — Data has integrity when it arrives complete (nothing missing or extra) and correct (nothing changed) compared with what was sent.

Section D: Fill in the Blanks

sent ← "HELLO"
received ← "HELLO"
IF received = sent THEN integrity ← TRUE

sentNum ← 5
gotNum ← 4
IF gotNum < sentNum THEN missing ← TRUE

sent ← "1011"
received ← "1001"
IF received ≠ sent THEN changed ← TRUE

sentNum ← 5
gotNum ← 6
IF gotNum > sentNum THEN extra ← TRUE

IF received = sent THEN OUTPUT "Intact"
ELSE OUTPUT "Resend needed"
ENDIF

Section E: Spot the Error

B — received must be the data that actually arrives over the network, so it should be RECEIVE(). Copying sent into received makes the check always pass, even if the data was damaged.

D — Fewer packets arrived than were sent (4 is less than 5), so the data is incomplete. The message should say 'Data is missing', not that there is extra data.

D — Both words have 3 letters, so nothing is missing. One letter (G) turned into T, so the data was changed. The message should say 'Data was changed'.

C — Data integrity needs the data to be complete AND correct. Using OR would say integrity is kept even when the data is missing pieces or has been changed.

A — JPEG is an image file format, not a network protocol. A protocol such as TCP is needed to check packets and ask for missing ones to be resent, which protects integrity.