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