Computer Science for IGCSE & O level - Data Transmission (Section 9)
1
What is a characteristic of the communication between sender and receiver in ARQ?
Απάντηση(C)
The receiver sends an acknowledgment.
2
Which of the following is an example of simplex data transmission?
Απάντηση(C)
Landing data from a computer to a printer
3
What is the primary purpose of the IP address in a data packet's header?
Απάντηση(B)
To identify the source and destination of the data.
4
What method of data transmission ensures that data is not lost or corrupted, by sending the data multiple times?
Απάντηση(C)
Automatic Repeat Request (ARQ)
5
What type of data transmission is used by a CB radio?
6
What is the main purpose of a 'key' in cryptography?
Απάντηση(C)
To encrypt and decrypt data.
7
What is the typical range of data transmission speed in a USB system?
8
Which of the following is an example of a public-key encryption algorithm?
9
What is 'CRC' used for in data transmission?
Απάντηση(B)
To ensure data integrity.
10
What is one of the primary benefits of using a USB connection?
Απάντηση(B)
It allows for easy connection and disconnection of devices.
11
What is the primary goal of an echo check?
Απάντηση(C)
To confirm data accuracy.
12
How does a receiving device know when it has received all packets?
Απάντηση(D)
When it has received all packets as indicated in the header.
13
What is the purpose of the extra bit added in a parity check?
Απάντηση(C)
To ensure that the total number of '1' bits is always even or odd
14
In the ISBN-13 example, what is the remainder after the calculation used to generate the check digit?
15
What is the main role of the IP address in the packet header?
Απάντηση(B)
To identify the source and the destination of the data.
16
What is the primary advantage of packet switching?
Απάντηση(C)
It is simple to expand and manage a network.
17
Which of the following methods are used to detect errors in data transmission?
18
What is a primary benefit of serial data transmission?
Απάντηση(C)
Requires fewer wires, simplifying cabling.
19
Which of the following is used for error detection in data transmission?
20
When employing asymmetric encryption, which of the following users would keep the private key?
21
What type of errors are check digits particularly useful in identifying?
Απάντηση(B)
Errors when data is typed or scanned.
22
What does 'CRC' stand for in the context of data transmission?
23
Which of the following is a characteristic of symmetric encryption?
Απάντηση(C)
Uses a single key for both encryption and decryption.
24
In the context of packet switching, what is the purpose of the 'sequence number'?
Απάντηση(B)
To help reassemble packets in the correct order.
25
When data is sent in packets, why is it necessary to reassemble the packets at the destination?
Απάντηση(A)
To ensure the correct order
26
What does the term 'bit' typically refer to in data transmission contexts?
Απάντηση(B)
The smallest unit of data, a binary digit (0 or 1).
27
Which transmission mode is used for a walkie-talkie?
28
What is the main purpose of the trailer section in a data packet?
Απάντηση(B)
To verify data integrity and detect errors.
29
In the context of a network, what is a 'node'?
Απάντηση(B)
A device connected to a network, such as a computer or a router.
30
What is an advantage of using USB (Universal Serial Bus)?
Απάντηση(C)
Devices can be automatically detected and drivers installed
31
What is an essential element of public-key cryptography?
Απάντηση(B)
A private key and a public key.
32
What role does a public key play in asymmetric encryption?
33
What is the role of sequence numbers in packetized data transmission?
Απάντηση(B)
To ensure data arrives in the correct order.
34
Which of the following terms represents the original message before it is encrypted, in the context of cryptographic techniques?
35
In symmetric encryption, which key is of the highest importance to safeguard?
36
What is a notable advantage of serial data transmission?
Απάντηση(B)
Requires fewer wires for data transfer.
37
What is a common application of asymmetric encryption?
Απάντηση(D)
Secure communication over a public network.
38
Which type of data transmission can send and receive data simultaneously?
39
What is the main advantage of using Checksum?
40
In asymmetric encryption, which key is used to encrypt data?
41
Which type of encryption uses a key to lock the data, while using another key to unlock it?
42
What is a characteristic of asymmetric key encryption?
Απάντηση(B)
Uses two mathematically linked keys (public and private).
43
What is the main difference between parallel and serial data transmission?
Απάντηση(B)
Parallel transmits bits simultaneously, while serial transmits bits sequentially.
44
What is a key used for in cryptography?
Απάντηση(B)
To encrypt and decrypt data.
45
Which key is used for encryption in public-key cryptography?
46
What is a key used for in data encryption?
Απάντηση(B)
To transform data into an unreadable format.
47
In the context of data transmission, what does 'CRC' stand for?
48
What is the function of the 'trailer' in a data packet?
Απάντηση(B)
To verify the data's integrity and detect transmission errors.
49
What is the primary objective of an echo check in data transmission?
Απάντηση(B)
To verify the accuracy of the data received.
50
Which method is often used to check for errors in packet data?
