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Computer Science for IGCSE & O level - Data Transmission (Section 15)

1
What is one of the methods used to generate a check digit?
Answer
(A)
ISBN 13
2
In asymmetric encryption, which key is used for decryption?
Answer
(B)
Private key
3
What method is used to check the integrity of data?
Answer
(C)
Checksums
4
Which device is primarily responsible for determining the most efficient path for data packets to reach their destination?
Answer
(C)
The router.
5
In data communication, what does ARQ stand for?
Answer
(B)
Automatic Repeat Request
6
Which of the following is NOT a characteristic of ARQ?
Answer
(C)
Always improving the speed.
7
Which component in a network is responsible for selecting the best route for data packets to their destination?
Answer
(C)
The router.
8
What type of error detection does a checksum fall under?
Answer
(C)
Block-level error detection
9
In the context of encryption, what is 'plaintext'?
Answer
(A)
The original, unencrypted data.
10
Why is serial data transmission often preferred for transmitting data over long distances?
Answer
(B)
Because it uses fewer wires, making cabling simpler and more cost-effective.
11
In the ISBN-13 example, what calculation is made with the digits of the ISBN to calculate the check digit?
Answer
(B)
Multiply alternate digits by 3 and add them up with the others.
12
What is the resulting output of encrypting a set of data?
Answer
(B)
Ciphertext
13
In cryptography, what is 'plaintext'?
Answer
(C)
The original, unencrypted message.
14
Which of the following is a characteristic of an echo check?
Answer
(B)
The sending device receives a copy of the transmitted data to confirm the reception.
15
In the ISBN-13 example, what is the next step after calculating the remainder?
Answer
(B)
Subtract the remainder from 10
16
Which of the following best describes what 'ciphertext' represents?
Answer
(C)
The encrypted form of a message.
17
What type of encryption uses a public key and a private key?
Answer
(B)
Asymmetric-key cryptography
18
What is the role of the check digit?
Answer
(A)
To ensure data integrity
19
Which of the following is a characteristic of symmetric encryption?
Answer
(C)
Uses a single key for both encryption and decryption.
20
What does the packet header usually contain?
Answer
(B)
The IP address of the sending device and IP address of the receiving device
21
What is the purpose of check digits in applications like ISBNs or vehicle identification numbers?
Answer
(C)
To detect errors introduced by typing or scanning.
22
What differentiates symmetric and asymmetric encryption?
Answer
(A)
Symmetric encryption uses one key for both encryption and decryption; asymmetric encryption uses two keys.
23
Which of the following techniques is most effective at detecting errors in large data transfers?
Answer
(C)
Automatic Repeat Request
24
Which element in a network is responsible for determining the best path for data packets to reach their destination?
Answer
(C)
The router.
25
What type of encryption uses a public key and a private key?
Answer
(B)
Asymmetric key encryption
26
What is the purpose of a USB-C connector?
Answer
(C)
To provide high-speed data transfer and power delivery
27
What mechanism does ARQ (Automatic Repeat Request) utilize for reliable data transfer?
Answer
(B)
Error detection and retransmission.
28
What are common factors that can lead to data corruption during transmission?
Answer
A
C
29
What is the result of encrypting plaintext?
Answer
(A)
Ciphertext
30
What can a positive acknowledgement signify within an ARQ protocol?
Answer
(A)
Data has been received.
31
In ARQ, what does a positive acknowledgement (ACK) signify?
Answer
(B)
The data was received without errors.
32
In which type of data transmission can data travel in both directions, but only one way at any given moment?
Answer
(B)
Half-duplex
33
Within a data packet, what is the primary role of the 'payload'?
Answer
(B)
To carry the actual data being transmitted.