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Computer Science for IGCSE & O level - Data Transmission (Section 14)

1
Which is the benefit of Checksum?
Answer
(A)
It ensures data has not been altered.
2
Which type of data transmission mode is suitable for a phone call?
Answer
(C)
Full-duplex
3
What does the ARQ protocol primarily aim to achieve?
Answer
(B)
Error correction.
4
What components make up a packet?
Answer
(B)
Header, Payload, and Trailer
5
What is the function of the IP address located in the header of a data packet?
Answer
(B)
To specify the sender and receiver of the data.
6
What does the 'payload' section of a data packet contain?
Answer
(B)
The actual data that is being transmitted.
7
Which type of encryption uses a single key for both encryption and decryption?
Answer
(B)
Symmetric encryption
8
Which of the following is a potential cause of data corruption?
Answer
A
C
9
What type of error detection is primarily used for data integrity during transmission?
Answer
(A)
Parity checks
10
In asymmetric encryption, which key is used to encrypt the data?
Answer
(B)
Public key
11
In a public key system, which key is kept secret?
Answer
(B)
Private Key
12
Which of the following is a key goal of cryptography?
Answer
(B)
To protect information from unauthorized access.
13
In asymmetric encryption, which key should be kept secret?
Answer
(B)
The private key.
14
Which security service can ensure that the sender can't deny that they sent a particular message?
Answer
(C)
Non-repudiation
15
In packet-switched data transmission, why are sequence numbers used?
Answer
(B)
To ensure that the packets arrive at the destination in the correct order.
16
What is an echo check used for?
Answer
(B)
To verify data accuracy.
17
In serial data transmission, the data bits are sent:
Answer
(B)
One after another over a single channel.
18
What is a primary goal of cryptography?
Answer
(C)
To protect information from unauthorized access.
19
What is the main objective of using parity checks in data transmission?
Answer
(B)
To detect errors.
20
In the context of data communication, what is an 'echo check' primarily used for?
Answer
(B)
Error detection
21
What is the main distinction between symmetric and asymmetric encryption?
Answer
(C)
Symmetric encryption uses one key, while asymmetric encryption uses two keys.
22
What is the main objective when using the parity check method?
Answer
(B)
To detect errors in the data
23
What is the unreadable format of data after encryption?
Answer
(B)
Ciphertext
24
What is the purpose of a public key?
Answer
(B)
To encrypt data.
25
In symmetric encryption, what is the primary requirement for maintaining data security?
Answer
(B)
Keeping the secret key protected.
26
What type of data transmission does a walkie-talkie use?
Answer
(B)
Half-duplex
27
What type of acknowledgement is sent when the data has an error?
Answer
(B)
Negative acknowledgement (NAK)
28
What is a key advantage of using serial data transmission over parallel transmission, particularly concerning the cabling?
Answer
(B)
Uses fewer wires, simplifying cabling and reducing cost
29
What security aspect does non-repudiation address?
Answer
(B)
Authenticity of the sender.
30
In the context of asymmetric encryption, what is the purpose of the private key?
Answer
(C)
To decrypt the data.
31
In the context of data transmission, what does the abbreviation 'CRC' stand for?
Answer
(A)
Cyclic Redundancy Check
32
What is the primary difference between symmetric and asymmetric encryption?
Answer
(A)
Symmetric uses one key, asymmetric uses two keys.
33
Which of the following methods are used to determine errors in the transmitted data? (Select all that apply)
Answer
A
B
C
34
In which data transmission mode can data be sent and received simultaneously?
Answer
(C)
Full-duplex
35
What is the main role of a 'router' in a network?
Answer
(B)
To connect different networks and forward data packets.
36
What are common causes of data corruption during transmission?
Answer
A
B
37
What information is typically included in the 'header' of a data packet?
Answer
A
C
D
38
Which of the following statements is most accurate regarding the use of ARQ?
Answer
(C)
ARQ is a mechanism for ensuring data reliability.
39
What is the primary role of the 'trailer' section in a data packet?
Answer
(B)
To detect and handle transmission errors.
40
What does the term 'trailer' refer to in data packet terminology?
Answer
(B)
The end of the packet, used for error detection and control.
41
Which type of key is kept secret in symmetric encryption?
Answer
(C)
A shared secret key
42
What does a timeout mechanism in ARQ primarily address?
Answer
(B)
Lost or delayed packets.
43
What are the typical components of a data packet?
Answer
A
B
C
44
What are the three factors that need to be considered when transmitting data?
Answer
(A)
Direction of transmission, method of transmission, and data synchronization
45
Which of the following describes the blocks where the receiving computer sends back a copy of the future the sending computer to allow it to compare the data?
Answer
(B)
automatic repeat request
46
What does a negative acknowledgment (NAK) indicate in the ARQ protocol?
Answer
(B)
Data has been corrupted during transmission.
47
What is the purpose of a timeout in an ARQ protocol?
Answer
(C)
To retransmit data if an acknowledgement is not received.
48
Which method is used if the receiving computer requests the data to be re-sent?
Answer
(B)
Automatic repeat request
49
What is the purpose of a 'checksum' in data transmission?
Answer
(B)
To detect errors during the transmission of data.
50
What is the purpose of the IP address in the packet header?
Answer
(B)
To identify the source and destination of the data.