Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Computer Science > Chapter 2 (2.1, 2.2, 2.3) Data Transmission > Flashcards

Chapter 2 (2.1, 2.2, 2.3) Data Transmission Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

packets

A

A small part of data is transmitted over a network usually 64 KiB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 3 components of a packet

A

Header
Payload
Trailer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Header

A

IP Address of sender and receiver

sequence number of packet - so that all the data can get reassembled

Size of packet In bytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Payload

A

The actual data

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Trailer

A

Method of identifying the end of
the packet

Error checking method

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Cyclic Redundancy Checks

A

Sending computer adds all the 1 bits in the payload and sends as a hex value in the trailer.
Receiving the computer recalculates the 1 bits and compares the value to the one in the trailer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Router

A

Receives a data packet and decides where to send next based on the information in the header

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Packet switching

A

Method of data transmission where data is broken down into packets and sent independently from the start point to the endpoint.
Packets get reassembled at the destination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

General process of packet switching

A

Data is broken down into packets
* Each packet could take a different route
* A router controls the route a packet takes (always selects the shortest path available)
* Packets may arrive out of order
* Once the last packet has arrived, packets are
reordered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Benefits of packet switching

A

High transmission rate
there is no need to tie up a single communication line
it is relatively easy to expand package usage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Drawbacks of packet switchign

A

packets can be lost and need to be re-sent
the method is more prone to errors with real-time streaming
there is a delay at the destination whilst the packets are being re-ordered.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Node

A

stages in a network that receive and transmit data packets.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

real-time streaming

A

Transmission of data for live events. It is sent as it is received or generated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Hop number

A

A number in the header that helps terminates lost packets so that the network doesn’t get clogged.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Factors considered why transmitting data

A

» the direction of data transmission

» the method of transmission

» how will data be synchronised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Simplex

A

Can be transferred only in one direction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Half-duplex

A

Can be transferred in both directions, but only one at a time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Full-duplex

A

Can be transferred in both directions, simultaneously.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Serial

A

Sending data down one channel/wire one bit at a time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Serial advantage

A

More reliable over longer distances

Data wont get skewed

Less expensive

21
Q

Parallel

A

Sending data down multiple channels/wires multiple bits at a time. (Usually 1 byte at a time)

22
Q

Parallel advantage

A

Faster rate of transmission than serial

Works better in shorter distances

easier to program input/output operations when parallel used

23
Q

Skewed data

A

Data arrives with bits that are unsynchronised.

24
Q

Universal Serial Bus (USB)

A

Serial data transmission which has become industry standard for connecting a computer to a device via a USB port.

25
Q

What happens when a device is plugged into a computer using a usb port

A

» the computer automatically detects that a device is present (this is due to a small change in the voltage on the data signal wires in the USB cable)
» the device is automatically recognised, and the appropriate device driver software is loaded up so that the computer and device can communicate
effectively
» if a new device is detected, the computer will look for the device driver that matches the device; if this is not available, the user is prompted to download the appropriate driver software

26
Q

USB Advantage

A

Industry standard - is compatible almost everywhere.
Plug and play - no external drivers need to be installed in order to use it
Different transmission rates 1.5mbps - 5gbps

27
Q

USB Disadvantage

A

Only up to 5m
V1 USB Isn’t supported on new computers

28
Q

Parity

A

Error checking method to check whether data has been changed or corrupted. This method is based on the number of 1 bits in the byte. If odd number then odd parity, if even number then even parity

29
Q

Parity bit

A

A bit added to the MSB of a byte to ensure that the byte follows either the even or odd parity protocol.

30
Q

Parity block

A

Horizontal and vertical parity check on a block of data that is being transmitted.

31
Q

Parity byte

A

Extra byte of data sent at the end of a parity block. Made of the parity bits from the vertical checks of a data block.

32
Q

Checksum

A

Error detection method that is calculated from the block of data that has been sent. Value is sent after each block.

33
Q

Process of checksum

A

» the checksum is calculated
from the block of data

» the calculation is done using an agreed algorithm

» the checksum is then transmitted with the block of data

» at the receiving end, the checksum is recalculated by the computer using the block of data

» the re-calculated checksum is then compared to the checksum sent with the data block

» if the two checksums are the same, then no transmission errors have occurred; otherwise a request is made to re-send the block of data.

34
Q

Check digit

what errors can it detect

A

Calculated from other digits in the code and detect errors in data entry.

Incorrect digit entered
Transposition errors
Omitted or extra digits
Phonetic errors

35
Q

ARQ - Automated Repeated Requests

A

Error checking method that uses a system of acknowledgements and timeouts. If the sender receives a negative acknowledgement from the receiver or it doesn’t receive any acknowledgement at all before the timeout, it will resend the data until a positive acknowledgement is received or a pre-determined number of re-transmissions has taken place. If the sender receives a positive acknowledgement then data has been transferred successfully.

36
Q

Echo check

A

Data is sent to a receiver, and then the receiver sends that data back to the sender to get compared. If it is corrupted, the sender resends the data .

37
Q

encryption

A

Process of making data useless without encryption keys. The correct key is required to decode the data.

38
Q

Symmetric encryption

A

The same encryption key is used to encrypt and decrypt a message.

39
Q

Asymmetric encryption

A

Uses public and private keys to ensure that data is secure.

40
Q

Public key

A

Key that is known to all users

41
Q

Private key

A

Key that is only known to a single user.

42
Q

What is an eavesdropper

A

Person that intercepts data being transmitted on a wired/wireless network

(hacker)

43
Q

What is plaintext
what is ciphertext

A

plaintext– the original text/message before it is put through an encryption algorithm

ciphertext – encrypted data that is the result of putting a plaintext message through an encryption algorithim

44
Q

What is an encryption Algorithm

A

a complex piece of software that takes plaintext and generates ciphertext

45
Q

Explain how asymmetric encryption works

A

First - Receiver uses an algorithm to generate a matching pair of keys. A public key and a private key

Second - The public key is sent to the sender.

Third - The sender uses the public key to encrypt the data (ciphertext) and sends it back to the receiver

Fourth - Receiver uses the matching private key to decrypt the ciphertext

46
Q

Can you use a public key to decrypt data in asymmetric encryption?

A

No

47
Q

Quantum computers

A

Very fast computers that can do calculations at a high speed. Performs calculations based on probability not 0 and 1 values. This means it can process a lot more data than a normal computer.

48
Q

Causes for errors in data transmission

A

» interference (all types of cable can suffer from electrical interference, which can cause data to be corrupted or even lost)

» problems during packet switching

» skewing of data (parallel data transmission - cause data corruption if the bits arrive out of synchronisation).

49
Q

Drawback of symmetric encryption

A

The security issue of keeping the key a secret since the same key is used by the sender and receiver

Computer Science (28 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions