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Computer Science IGCSE > 2. Data Transmission > Flashcards

2. Data Transmission Flashcards

1
Q

What are packets?

A

Small ‘chunks’ of data that make up a larger piece of data that has been broken down by TCP protocol so that it can be transmitted over the internet.

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2
Q

What does TCP stand for?

A

Transmission Control Protocol

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3
Q

What are the three main components of a packet?

A

Header
Payload
Trailer

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4
Q

What does the PAYLOAD contain?

A

The actual data being transported in a packet

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5
Q

What information is typically included in a packet’s HEADER?

A

Source IP address
Destination IP adress
Packet number

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6
Q

What is the purpose of error checking in packets?

A

To ensure that when a packet is received there is minimal or no corruption of the data

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7
Q

How is a parity bit used for error detection?

A

A bit added to a packet to check that no bits have been filled from 0 to 1

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8
Q

How is a checksum used for error detection?

A

A calculation performed on packet data to detect corruption by comparing the result to a stored checksum value

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9
Q

What is corruption in the context of data packets?

A

Where packet data is changed or lost in some way, or data is gained that originally was not in the packet

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10
Q

What is packet switching?

A

A method of sending and receiving data across a network, the packs of data ae sent via different routers

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11
Q

What is the method of packet switching

A

Data is broken down into packets
Each packer is assigned a sequence number
Each packet can take its own route based on congestion
Routers are responsible for controlling the route each packet rakes
Packers may arrive out of order. Once the final packet arrives, they are reordered

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12
Q

What is the role of routers in packet switching?

A

Routers control the routes taken for each packet and decide which nearby router is closer to the destination device.

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13
Q

What happens if a packet does not reach its destination?

A

The receiver can send a resend request to the sender to resend the packet

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14
Q

What is one advantage of packet switching in terms of data security?

A

It’s harder to hack an individual’s data as each packet contains minimal data and travels through the network separately

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15
Q

Why is packet switching generally faster than sending a large packet?

A

Each packet finds the quickest way around the network

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16
Q

What happens to packets when they arrive at their destination?

A

They are reordered correctly to reconstruct the original data

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17
Q

What is the benefit of packet switching in terms of network efficiency?

A

Allows multiple users to share the same data path

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18
Q

What is data transmission?

A

The process of transferring data from one device to another using a wired or wireless connection

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19
Q

What are two types of wired data transmission

A

Serial and Parallel

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20
Q

What is serial transmission?

A

A method where a stream of bits is sent in a sequence, one after the other

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21
Q

What is parallel transmission?

A

A method where a stream of bits is sent in a sequence one after the other across multiple wires at the same time.

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22
Q

What is a skew in parallel transmission?

A

When data arrives out of order in asynchronous (non-existing) parallel transmission

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23
Q

What is an advantage of serial transmission over parallel transmission.

A

More reliable over longer distances

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24
Q

What is simplex transmission?

A

A method where data travels in only one direction

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25
Q

What is half-duplex transmission?

A

A method where data can travel in both directions, but not simultaneously

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26
Q

What is a full-duplex transmission?

A

A method where data can travel in both directions at the same time

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27
Q

What does a USB stand for

A

Universal Serial Bus

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28
Q

What type of data transmission does USB use?

A

Asynchronous and serial data transmission

29
Q

Name three types of USB connectors

A

USB - A
USB - B
USB - C

30
Q

What happens when a device is connected to a USB port?

A

The computer automatically detects the device and loads the appropriate driver

31
Q

What is backward compatibility in USB?

A

newer USB standards cam work with older USB devices and ports

32
Q

What is interference in data transmission?

A

Any disturbance that can cause errors in the data being sent

33
Q

Define data loss

A

When some data is lost during transmission

34
Q

What is data gain

A

When additional data is received beyond what was originally sent

35
Q

Define data change

A

When some bits in the transmitted data have been altered or flipped

36
Q

What can cause interference in wireless technology?

A

Physical barriers
Bad weather
Other wireless signals

37
Q

What is a format?

A

A way of arranging data so that it can be easily understood by people and computers

38
Q

Why is it important to check for errors in data transmission?

A

Computer expect data in certain formats and if data is not as expected, things can go wrong

39
Q

Define corruption in data transmission?

A

When data received is not as expected and therefore is difficult or impossible to process.

40
Q

What is a parity check

A

A method to determine whether bits in a transmission have been corrupted

41
Q

Define parity bit

A

A bit added to each byte transmitted to ensure the total number of 1s in the byte matches the agreed parity

42
Q

What is the difference between odd and even parity

A

Odd parity requires an odd number of 1’s in the byte, while even parity requires an even number of 1s

43
Q

What is a parity block?

A

A block of data with the number of 1’s totalled horizontally and vertically to check for errors and locate where they occurred

44
Q

What is parity byte

A

A byte sent with the data which contains the parity bits from the vertical parity calculation in a parity block

45
Q

How does an echo check work?

A

Transmits the received data back to the sender who then checks the data to see if any errors occurred during transmission

46
Q

What is the main disadvantage of an echo check?

A

It isn’t as reliable as an error could have occurred when the sender transmits the data or when the receiver transmits the data back

47
Q

How does a checksum algorithm determine if an error has occurred?

A

Calculates a checksum value before transmission, sending it with data, recalculating it upon receipt, and comparing the two values. If they match no error has occurred.

48
Q

What is a check digit

A

A digit added to the end of a block of data to determine if the data has been corrupted

49
Q

Define ISBN

A

A unique identifier for books that includes a check digit for error detection

50
Q

How many digits are in a standard ISBN number?

A

10 digits

51
Q

Where is the check digit located in an ISBN number?

A

The final digit

52
Q

What is a barcode

A

A series of black and white lines that can be scanned to identify an item, often including a check digit for validation

53
Q

What is the purpose of a check digit in a barcode?

A

To validate and authenticate an item

54
Q

What is the main limitation of check digits?

A

They can determine if data has been corrupted but do not reveal where the corruption has occurred

55
Q

Define Automatic Repeat Request (ARQ)

A

A protocol that notifies the sender that an error has occurred and that the data is received is incorrect

56
Q

What is a negative acknowledgement transmission in ARQ?

A

A negative acknowledgment transmission in ARQ is a message sent by the receiver to indicate that the data is corrupted.

57
Q

Define positive acknowledgement transmission in ARQ

A

A message sent by the receiver to indicate that the data is correct.

58
Q

What is a time-out in ARQ?

A

A certain time period that the sender waits before automatically resending the data if no acknowledgement is received

59
Q

What happens if the receiver doesn’t send any acknowledgement in ARQ?

A

The sender waits for a time-out period before automatically resending the data

60
Q

How does ARQ handle corrupted data?

A

The receiver sends a negative acknowledgement prompting the sender to resend the data

61
Q

How does ARW differ from other error detection methods?

A

it actively requires retransmission of corrupted data, rather than just receiving errors

62
Q

What is encryption?

A

A method of scrambling data before being transmitted across a network in order to protect the contents from unauthorised access

63
Q

Define SSID

A

SSID is Service Set Identifier, which along with a password is used to create a ‘master key’ for wireless network encryption

64
Q

What is cipher text?

A

Encrypted data that has been scrambled using a master key

65
Q

Define plaintext

A

The name fir data before it is encrypted

66
Q

What is symmetric encryption?

A

When both the sender and receiver are given an identical secret key which can be used to encrypt or decrypt information

67
Q

Define asymmetric encryption?

A

When two keys are used, a public key known to everyone and a private key known only to the receiver

68
Q

What protocol is specifically designed for Wi-Fi security?

A

WPA2 is specifically designed for Wi-Fi security

69
Q

Define public key

A

A key known to everyone in asymmetric encryption

Computer Science IGCSE (2 decks)

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