Computer Science for IGCSE & O level - Data Transmission (Section 5)
1
Which of the following statement(s) is/are true about the Transport Layer?
Απάντηση
A
C
2
Which of the following are used for error detection?
Απάντηση
A
B
3
What kind of error detection is used when data are sent back to the sender?
Απάντηση
(C)
Echo check
4
Which error-detection technique typically involves the retransmission of data?
Απάντηση
(D)
Automatic Repeat Request (ARQ)
5
Which term applies to a situation where two digits swap their positions in the process of data entry?
Απάντηση
(B)
Transposition Error
6
Which of the following would be best suited for a two-way communication?
Απάντηση
(C)
Full-duplex communication
7
In encryption, which of the following terms is used to describe the message before it is encrypted?
Απάντηση
(B)
Plaintext
8
What is the first number in a node, which is calculated from all the numbers in the code, to ensure the errors in data entry?
Απάντηση
(C)
Check digit
9
What does the term 'encryption' mean?
Απάντηση
(A)
The process of converting data into an unreadable format.
10
What is the main security benefit of using a VPN?
Απάντηση
(B)
It protects your internet traffic from eavesdropping and censorship.
11
Which of the following is a type of attack that attempts to make a network resource unavailable to its intended users?
Απάντηση
(C)
Denial-of-service (DoS)
12
In packet switching, what information does the header include to make sure that the packets can be assembled in the correct order?
Απάντηση
(C)
Sequence number.
13
Which of the following is a benefit of using a switch compared to a hub?
Απάντηση
(C)
Switches forward traffic only to the intended recipient, increasing efficiency.
14
In packet switching, what are the advantages of using different routes?
Απάντηση
B
C
15
Why are packets sometimes reordered when using packet switching?
Απάντηση
(A)
Because each packet may take a different route.
16
What is the function of 'ARP' (Address Resolution Protocol)?
Απάντηση
(B)
To resolve IP addresses to MAC addresses.
17
What is the main security risk associated with using symmetric encryption?
Απάντηση
(A)
The same key is used for both encrypting and decrypting, which can make it difficult to share the key securely.
18
What are some of the main advantages of a wireless network (Wi-Fi)?
Απάντηση
A
B
19
Which of the following is NOT a characteristic of full-duplex data transmission?
Απάντηση
(C)
A single channel is used for transmission.
20
Which of the following statements is true regarding symmetric encryption?
Απάντηση
(C)
It uses the same key for encryption and decryption.
21
Which of the following factors influence how data is transmitted?
Απάντηση
A
B
C
22
In a network, what task does a router primarily perform?
Απάντηση
(B)
Forwarding data packets.
23
Which of the following best describes the operation of an echo check?
Απάντηση
(B)
The receiver sends a copy of the data back to the sender to verify it.
24
What is 'social engineering'?
Απάντηση
(C)
The practice of manipulating people into revealing confidential information.
25
What kind of error could be detected by parity blocks?
Απάντηση
(D)
Both single and burst errors and errors where one bit has changed
26
Which of the following is a function of the 'application layer' of the OSI model?
Απάντηση
(C)
Providing network services to applications.
27
Which of the following best describes "automatic repeat request (ARQ)"?
Απάντηση
(B)
A system for detecting and correcting errors by retransmitting data.
28
In the context of data transmission, what does the term "checksum" refer to?
Απάντηση
(B)
A method of error detection.
29
What does the acronym ARQ stand for?
Απάντηση
(B)
Automatic Repeat Request
30
What are the common methods for detecting errors in data transmission?
Απάντηση
A
B
C
31
What is a 'MAC address' used for?
Απάντηση
(A)
To identify a device on a network at the data link layer.
32
What does USB stand for?
Απάντηση
(A)
Universal Serial Bus
33
What is the key difference between serial and parallel data transmission?
Απάντηση
(A)
Serial transmits data one bit at a time, while parallel transmits several bits simultaneously.
34
When using asymmetric encryption, how is the sender's private key typically used?
Απάντηση
(C)
To create a digital signature.
35
Which of the following are examples of network protocols?
Απάντηση
A
B
C
D
36
What does 'VPN' stand for?
Απάντηση
(A)
Virtual Private Network
37
What is 'spoofing' in a network context?
Απάντηση
(B)
An attack where an attacker impersonates a legitimate entity.
38
What is the purpose of a public key in asymmetric encryption?
Απάντηση
(B)
To encrypt messages only.
39
What is the primary function of the "header" in a data packet?
Απάντηση
(B)
Provides information about the data, such as source and destination addresses.
40
What type of transmission is often used for connecting a computer to a printer via a USB connection?
Απάντηση
(C)
Full-duplex
41
In the example of ISBN-13 algorithm where 978030640615X, what is the calculation algorithm is used?
Απάντηση
(A)
Weighted sum and then divide by 10 to find remainder
42
Why are check digits used?
Απάντηση
(C)
To detect errors, such as when data is entered incorrectly.
43
What is the primary benefit of breaking data into packets before transmission?
Απάντηση
(C)
It allows data to be sent via a different route.
44
Which of the following protocols is often used to encrypt web traffic?
Απάντηση
(C)
HTTPS
45
What is the term for the combination of hardware and software that translates signals from a computer into signals that can be transmitted over a phone line?
Απάντηση
(C)
Modem
46
Which of the following is the correct name for a form of encryption that involves both the sender and the recipient use the same key to encrypt and decrypt?
Απάντηση
(A)
Symmetric key encryption
47
Which of the following is an example of a "checksum"?
Απάντηση
(B)
A hash value used to verify data integrity
48
What is the function of a 'checksum' in data transmission?
Απάντηση
(B)
To detect errors in the data.
49
In asymmetric encryption, what happens if someone has your public key?
Απάντηση
(B)
They can encrypt messages to you.
50
Which method is most suitable for long-distance communication?
