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Computer Science for IGCSE & O level - Data Transmission (Section 8)

1
What is the function of a checksum in data transmission?
Answer
(B)
To detect errors in the data.
2
When using asymmetric encryption, who typically has the public key?
Answer
(D)
Anyone who wants to send a message to the receiver.
3
What does the term
Answer
(B)
The original, unencrypted data.
4
Which of the following is true regarding the security of the public key in asymmetric encryption?
Answer
(B)
It can be shared with anyone.
5
In the context of quantum cryptography, what does polarization of photons represent?
Answer
(A)
Data
6
What is typically accomplished by a digital signature?
Answer
A
C
7
What is the outcome of the encryption process?
Answer
(B)
Ciphertext
8
Which of the following is a key advantage of serial data transmission, especially when compared to parallel transmission?
Answer
(B)
Reduced complexity in cabling, and therefore lower cost.
9
What is a 'hop number' in packet switching used for?
Answer
(C)
Preventing packets from circulating indefinitely.
10
What is a key advantage of using packet switching?
Answer
(D)
Improved expandability.
11
What is the primary advantage of serial data transmission over parallel data transmission, particularly for long-distance communication?
Answer
(B)
Lower cost due to simpler wiring.
12
What is the function of the 'header' in a data packet?
Answer
(B)
To provide information about the packet (e.g., source and destination).
13
What distinguishes symmetric encryption from asymmetric encryption?
Answer
(A)
Symmetric uses one key; asymmetric uses two.
14
What is the primary purpose of parity checks in the context of data communication?
Answer
(C)
To detect errors in the transmitted data.
15
In the context of asymmetric encryption, which key is kept confidential?
Answer
(B)
Private Key
16
What is the purpose of a check digit in data transmission?
Answer
(C)
To detect errors in the data
17
What technique is most commonly used for ensuring that data is transmitted without corruption?
Answer
(C)
Checksums
18
What is the relationship between serial and parallel data transmission in the context of distance?
Answer
(A)
Serial is better for longer distances
19
Which of the following is a key characteristic of full-duplex data transmission?
Answer
(C)
Data can be sent in both directions simultaneously.
20
What is the main difference between symmetric and asymmetric key cryptography?
Answer
(C)
Symmetric uses a single key, asymmetric uses a key pair.
21
What does the abbreviation 'ARQ' stand for?
Answer
(B)
Automatic Repeat Request
22
What is the role of the trailer in a packet?
Answer
(C)
To detect transmission errors.
23
In asymmetric encryption, what is the private key primarily used for?
Answer
(C)
Decrypting the data.
24
What is the primary function of a checksum in data transmission?
Answer
(B)
To verify the integrity of the data.
25
When data is encrypted, which of the following happens to the data?
Answer
(B)
It is transformed into an unreadable format.
26
In the context of encryption, what is meant by 'cipher text'?
Answer
(C)
The result of encrypting data.
27
What is the result of encrypting the data?
Answer
(B)
Ciphertext
28
What is the main function of a checksum?
Answer
(B)
To ensure data integrity.
29
If a byte using even parity contains the bits 1011001, what should the parity bit be?
Answer
(A)
0
30
What is the main purpose of the 'payload' section in a data packet?
Answer
(B)
To hold the actual data that is being transmitted.
31
What's the purpose of a negative acknowledgment (NAK) within the ARQ protocol?
Answer
(B)
To request a retransmission of the data.
32
Which term describes a message that has been encrypted?
Answer
(B)
Ciphertext
33
What is a common cause of data corruption during transmission?
Answer
A
B
34
What does the 'hop number' represent in packet switching?
Answer
(A)
The number of routers a packet has visited.
35
What is the primary purpose of check digits?
Answer
(B)
To detect data entry errors.
36
In asymmetric encryption, what is the intended use of the public key?
Answer
(C)
To encrypt the data.
37
Which mode of transmission is employed by a citizen's band (CB) radio?
Answer
(B)
Half-duplex
38
Which of the following can cause data corruption during transmission?
Answer
A
B
39
In the context of cryptography, what is meant by 'confidentiality'?
Answer
(B)
Preventing unauthorized disclosure of information.
40
What is a key advantage of serial data transmission regarding the number of wires required?
Answer
(B)
Requires fewer wires.
41
In asymmetric encryption, which key is distributed publicly?
Answer
(B)
Public Key
42
What type of acknowledgement indicates that the data has been received successfully?
Answer
(C)
Positive Acknowledgement (ACK)
43
What term refers to data that has been transformed into an unreadable form?
Answer
(B)
Ciphertext
44
What is the primary function of the parity bit in data transmission?
Answer
(B)
To detect transmission errors.
45
What security is crucial for symmetric encryption?
Answer
(C)
Protecting the secret key.
46
Which of the following is a characteristic of symmetric encryption?
Answer
(C)
Easy to implement and fast.
47
Which of the following error detection methods can detect single-bit errors, and some forms of multi-bit errors?
Answer
(D)
Cyclic Redundancy Check
48
What is the primary function of a Digital Signature?
Answer
(B)
To verify the integrity and authenticity of the data.
49
What is the term used to describe data that is in an unreadable format?
Answer
(B)
Ciphertext
50
What is an example of block-level error detection?
Answer
(B)
Checksum