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Computer Science IGCSE > 2. Data Transmission > Flashcards

2. Data Transmission Flashcards

(69 cards)

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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
What is half-duplex transmission?
A method where data can travel in both directions, but not simultaneously
26
What is a full-duplex transmission?
A method where data can travel in both directions at the same time
27
What does a USB stand for
Universal Serial Bus
28
What type of data transmission does USB use?
Asynchronous and serial data transmission
29
Name three types of USB connectors
USB - A USB - B USB - C
30
What happens when a device is connected to a USB port?
The computer automatically detects the device and loads the appropriate driver
31
What is backward compatibility in USB?
newer USB standards cam work with older USB devices and ports
32
What is interference in data transmission?
Any disturbance that can cause errors in the data being sent
33
Define data loss
When some data is lost during transmission
34
What is data gain
When additional data is received beyond what was originally sent
35
Define data change
When some bits in the transmitted data have been altered or flipped
36
What can cause interference in wireless technology?
Physical barriers Bad weather Other wireless signals
37
What is a format?
A way of arranging data so that it can be easily understood by people and computers
38
Why is it important to check for errors in data transmission?
Computer expect data in certain formats and if data is not as expected, things can go wrong
39
Define corruption in data transmission?
When data received is not as expected and therefore is difficult or impossible to process.
40
What is a parity check
A method to determine whether bits in a transmission have been corrupted
41
Define parity bit
A bit added to each byte transmitted to ensure the total number of 1s in the byte matches the agreed parity
42
What is the difference between odd and even parity
Odd parity requires an odd number of 1's in the byte, while even parity requires an even number of 1s
43
What is a parity block?
A block of data with the number of 1's totalled horizontally and vertically to check for errors and locate where they occurred
44
What is parity byte
A byte sent with the data which contains the parity bits from the vertical parity calculation in a parity block
45
How does an echo check work?
Transmits the received data back to the sender who then checks the data to see if any errors occurred during transmission
46
What is the main disadvantage of an echo check?
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
How does a checksum algorithm determine if an error has occurred?
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
What is a check digit
A digit added to the end of a block of data to determine if the data has been corrupted
49
Define ISBN
A unique identifier for books that includes a check digit for error detection
50
How many digits are in a standard ISBN number?
10 digits
51
Where is the check digit located in an ISBN number?
The final digit
52
What is a barcode
A series of black and white lines that can be scanned to identify an item, often including a check digit for validation
53
What is the purpose of a check digit in a barcode?
To validate and authenticate an item
54
What is the main limitation of check digits?
They can determine if data has been corrupted but do not reveal where the corruption has occurred
55
Define Automatic Repeat Request (ARQ)
A protocol that notifies the sender that an error has occurred and that the data is received is incorrect
56
What is a negative acknowledgement transmission in ARQ?
A negative acknowledgment transmission in ARQ is a message sent by the receiver to indicate that the data is corrupted.
57
Define positive acknowledgement transmission in ARQ
A message sent by the receiver to indicate that the data is correct.
58
What is a time-out in ARQ?
A certain time period that the sender waits before automatically resending the data if no acknowledgement is received
59
What happens if the receiver doesn't send any acknowledgement in ARQ?
The sender waits for a time-out period before automatically resending the data
60
How does ARQ handle corrupted data?
The receiver sends a negative acknowledgement prompting the sender to resend the data
61
How does ARW differ from other error detection methods?
it actively requires retransmission of corrupted data, rather than just receiving errors
62
What is encryption?
A method of scrambling data before being transmitted across a network in order to protect the contents from unauthorised access
63
Define SSID
SSID is Service Set Identifier, which along with a password is used to create a 'master key' for wireless network encryption
64
What is cipher text?
Encrypted data that has been scrambled using a master key
65
Define plaintext
The name fir data before it is encrypted
66
What is symmetric encryption?
When both the sender and receiver are given an identical secret key which can be used to encrypt or decrypt information
67
Define asymmetric encryption?
When two keys are used, a public key known to everyone and a private key known only to the receiver
68
What protocol is specifically designed for Wi-Fi security?
WPA2 is specifically designed for Wi-Fi security
69
Define public key
A key known to everyone in asymmetric encryption

Computer Science IGCSE (2 decks)

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