Computer Science for IGCSE & O level - Data Transmission (Section 6)
1
Which of these methods require a round-trip of data?
Απάντηση
B
D
2
What kind of information are used to generate a check digit?
Απάντηση
B
C
D
3
What is the purpose of a 'proxy server'?
Απάντηση
(B)
To filter and cache network traffic.
4
Which of the following are examples of network security threats?
Απάντηση
A
B
C
5
In the context of asymmetric encryption, who is the sender?
Απάντηση
(A)
The follower
6
What is the function of 'segmentation' in data transmission?
Απάντηση
(B)
To divide data into smaller, manageable units for transmission.
7
Which is used to identify the errors in data entry?
Απάντηση
(B)
Check digits
8
How do echo checks identify errors?
Απάντηση
(A)
By sending the data back to the sender.
9
Which of the following are examples of wired network technologies?
Απάντηση
A
C
10
What is 'social engineering'?
Απάντηση
(B)
The practice of manipulating people to gain information.
11
What distinguishes a full-duplex communication mode?
Απάντηση
(B)
Data is sent in both directions simultaneously.
12
Which of the following is NOT a component of a typical packet header?
Απάντηση
(C)
The payload.
13
What is the role of a private key in asymmetric encryption?
Απάντηση
(C)
Decrypt data that was encrypted with the corresponding public key.
14
What are the common causes of data corruption during transmission?
Απάντηση
A
B
C
15
Which of the following is the biggest disadvantage of using asymmetric encryption?
Απάντηση
(A)
It is very complex and time-consuming
16
Which of the following is considered a 'layer 1' protocol in the OSI model?
Απάντηση
(D)
The physical layer
17
What does the term 'firewall' primarily do in terms of network security?
Απάντηση
(B)
Filters network traffic based on predefined rules.
18
What does full-duplex communication allow?
Απάντηση
(B)
Data to be sent in both directions simultaneously.
19
What is the purpose of error-checking methods such as checksums and parity bits?
Απάντηση
A
C
20
How does 'red-time streaming' relate to packet switching?
Απάντηση
(A)
It increases the likelihood of packets getting reordered.
21
What are the key characteristics of serial data transmission?
Απάντηση
(A)
Sends bits one at a time over a single channel.
22
What is the role of a sequence number in the packet header?
Απάντηση
(B)
To reassemble packets in the correct order.
23
What type of data transmission is commonly used for longer distances?
Απάντηση
(C)
Serial
24
Which type of data transmission is usually preferred for long distances?
Απάντηση
(B)
Serial data transmission.
25
In the context of ISBN-13 calculation, which operation is used to calculate the check digit?
Απάντηση
(B)
Modulo
26
What is the main advantage of asymmetric encryption over symmetric encryption?
Απάντηση
(C)
Higher data security
27
What is an example of "plaintext"?
Απάντηση
(D)
An email's body before encryption
28
What is the main limitation of using parity checks for error detection?
Απάντηση
(A)
It can only detect single-bit errors.
29
What is a key advantage of using packet switching in a network?
Απάντηση
(B)
More efficient use of network resources.
30
Which of the following are types of error detection techniques?
Απάντηση
A
B
31
What are the benefits of using a USB system?
Απάντηση
A
B
C
32
What is the function of the 'sequence number' in a packet's header?
Απάντηση
(C)
To help reassemble packets in the correct order.
33
What is the role of the 'payload' in a data packet?
Απάντηση
(B)
To contain the actual data being transmitted.
34
How does half-duplex data transmission work?
Απάντηση
(B)
Data is sent in one direction at a time.
35
Which of the following uses an excluded value which is a result after blocks of data, the receiving computer also calculates the value from the blocks of data and compares the values?
Απάντηση
(C)
Checksum
36
Which layer of the OSI model is responsible for formatting the data before transmission?
Απάντηση
(A)
The Presentation Layer
37
What can cause data corruption during transmission?
Απάντηση
A
C
38
Which type of transmission mode allows for sending data in only one direction?
Απάντηση
(C)
Simplex
39
In the context of data security, what does "encryption" achieve?
Απάντηση
(B)
Protects data by converting it into an unreadable format.
40
What is the primary purpose of the OSI model?
Απάντηση
(B)
To provide a framework for understanding how networks operate.
41
Which of the following scenarios would be most likely to cause an error detectable by a parity check?
Απάντηση
(A)
A single bit is flipped during transmission.
42
What is 'malware'?
Απάντηση
(B)
Software designed to damage or disrupt a computer system.
43
What is the primary goal of using error detection methods in data transmission?
Απάντηση
(C)
To identify and handle transmission errors.
44
What is a primary advantage of asymmetric encryption?
Απάντηση
(B)
Simplified key exchange.
45
Which mode enables two-way communication at the same time?
Απάντηση
(C)
Full-duplex
46
Which of the following is true about the security of symmetric encryption?
Απάντηση
(A)
The key must be kept secret.
47
What type of error detection involves sending data twice and comparing the two instances?
Απάντηση
(C)
Repetition
48
What are the possible causes of data corruption during data transmission?
Απάντηση
A
B
C
49
What is the result of the ISBN-13 calculation for the number 978030640615X (where X represents the check digit)?
Απάντηση
(C)
2
50
What is the role of 'authentication' in data security?
