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Computer Science for IGCSE & O level - Data Transmission (Section 11)

1
What does 'ciphertext' refer to in the context of cryptography?
Answer
(C)
The encrypted form of the data.
2
What is one way that the sender knows the data has been successfully delivered?
Answer
(B)
The receiver acknowledges the data.
3
What is the main purpose of a hashing algorithm?
Answer
(B)
To verify data integrity.
4
In the ISBN-13 calculation, what is done after calculating the remainder?
Answer
(B)
Subtract from 10.
5
What do you call the process of converting data from a readable format to an unreadable format?
Answer
(C)
Encryption
6
Which of the following is an error detection mechanism?
Answer
(C)
Checksum
7
What does CRC stand for?
Answer
(C)
Cyclic Redundancy Check
8
What is the main goal of an error detection code?
Answer
(B)
To ensure data has arrived correctly.
9
If you are using odd parity and the data byte is 01100011, what will the parity bit be?
Answer
(A)
0
10
What typically constitutes a data packet?
Answer
A
B
C
11
What is the primary goal of error detection codes?
Answer
(B)
To identify if any errors occurred during transmission.
12
What does the term 'payload' represent within a data packet?
Answer
(B)
The actual data being transmitted.
13
What is the benefit of using a digital signature?
Answer
(C)
It guarantees message authenticity and non-repudiation.
14
What type of key is shared in symmetric encryption?
Answer
(C)
A secret key
15
What is a defining characteristic of symmetric encryption?
Answer
(C)
It's generally faster and simpler.
16
In packet switching, the 'hop number' indicates what?
Answer
(B)
The number of routers a packet has already passed through.
17
What type of encryption is generally faster and simpler?
Answer
(A)
Symmetric
18
Which of the following is NOT a form of error detection?
Answer
(C)
Encryption
19
What is the main benefit of serial data transmission?
Answer
(B)
Requires fewer wires.
20
What is the main function of a USB connector?
Answer
(B)
To provide a universal interface for connecting devices.
21
What is the principal mechanism utilized by ARQ to ensure reliable data transmission?
Answer
(C)
Retransmission of data.
22
What is a 'trailer' in the context of data packets?
Answer
(C)
Information used to detect errors in transmission.
23
What is the primary aim of symmetric encryption?
Answer
(B)
To establish a secure communication channel.
24
In which mode does data transmission occur in only one direction?
Answer
(C)
Simplex
25
What does a digital signature provide?
Answer
B
C
26
In symmetric encryption, what is the primary requirement for secure data transmission?
Answer
(C)
Securing the secret key.
27
How are checksums typically calculated?
Answer
(B)
By adding up the data values and taking the remainder after division by a certain number.
28
What is the main advantage of using a digital signature?
Answer
(A)
Ensures data has not been altered.
29
What is the main goal of using checksums in data communication?
Answer
(B)
To ensure the data's integrity.
30
What is used to decrypt data in asymmetric encryption?
Answer
(B)
The private key
31
In the context of data transmission, what does 'ARQ' stand for?
Answer
(C)
Automatic Repeat Request
32
Which method is used to convert the data to an unreadable format?
Answer
(A)
Encryption
33
In the context of data transmission, what does 'ARQ' stand for?
Answer
(B)
Automatic Repeat Request
34
What is the purpose of using a public key?
Answer
(B)
Encrypt a message.
35
What is the major security consideration when using symmetric encryption?
Answer
(B)
The key.
36
Which type of encryption uses a single key for both encryption and decryption?
Answer
(B)
Symmetric encryption
37
What is the purpose of a 'sequence number' in a packet?
Answer
(C)
To ensure packets are reassembled in the correct order.
38
What does a router do in packet switching?
Answer
(C)
Decides where to send the next packet.
39
What is the role of encryption in data security?
Answer
(C)
To protect data from unauthorized access.
40
What is the significance of a 'positive acknowledgement' in ARQ?
Answer
(A)
It means the data has been received correctly.
41
What is a key used for in cryptography?
Answer
(B)
To transform data into ciphertext and back.
42
Which of the following can cause data corruption during transmission?
Answer
A
C
43
What is one of the benefits of USB-C compared to older USB versions?
Answer
(C)
Provides higher power delivery capabilities.
44
What is the main function of error detection codes?
Answer
(C)
To identify changes in the data.
45
What distinguishes half-duplex from full-duplex data transmission?
Answer
(B)
Half-duplex transmits data in one direction at a time; full-duplex transmits in both directions simultaneously.
46
Which of the following methods uses an extra bit added to a byte to ensure an even or odd number of 1s or add number of 1?
Answer
(B)
Parity check
47
What is the primary function of a hashing algorithm?
Answer
(C)
To create a unique 'fingerprint' of data.
48
The secrecy of which element is most critical in symmetric encryption?
Answer
(C)
The secret key.
49
In the ISBN-13 system, what is the purpose of the check digit?
Answer
(B)
To verify the validity of the ISBN.
50
What is the role of a 'timeout' in ARQ?
Answer
(B)
To retransmit data if no acknowledgement is received.