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Computer Science for IGCSE & O level - Data Transmission (Section 1)

1
What is the function of the 'trailer' in a data packet?
Answer
(C)
To detect transmission errors.
2
Which technique does a checksum employ to detect errors in data transmission?
Answer
(B)
Calculating a numerical value and comparing it at the receiver.
3
What type of data transmission is best suited for an internet connection?
Answer
(C)
Full-duplex.
4
Which of the following is a key characteristic of quantum cryptography?
Answer
(A)
Relies on the principles of quantum mechanics.
5
Which of the following methods uses an extra bit added to a byte to ensure an even number of 1s or an odd number of 1s?
Answer
(B)
Parity check
6
What does 'hop number' control in a packet-switched network?
Answer
(B)
The packet's lifespan.
7
What is "plaintext" in the context of cryptography?
Answer
(B)
The original, unencrypted message
8
In asymmetric encryption, who should keep the private key secret?
Answer
(B)
The receiver.
9
What does the 'sequence number' in a packet's header ensure?
Answer
(A)
The order of transmission of the packets
10
What is the purpose of a 'router' in a network?
Answer
A
C
11
Which is a characteristic of serial data transmission?
Answer
(B)
Suitable for long distances.
12
What is the main purpose of 'hashing' in data security?
Answer
(B)
To create a unique fingerprint of data for integrity verification.
13
What is the function of the 'data link layer' in the OSI model?
Answer
(A)
Providing reliable node-to-node data transfer.
14
In the context of packet switching, what is the role of a 'router'?
Answer
(C)
To determine the best path for each packet.
15
In the ISBN-13 calculation, what is the weight assigned to the first digit?
Answer
(A)
1
16
Which error-detection method is based on calculating a value using all bits in the payload?
Answer
(C)
Checksum.
17
What is the defining characteristic of 'Simplex' data transmission?
Answer
(A)
Data transmission in one direction only.
18
What is the purpose of the 'trailer' in a data packet?
Answer
(C)
To help detect transmission errors.
19
In an ARQ system, what does a 'negative acknowledgement' (NAK) indicate?
Answer
(C)
The receiver has detected an error in the received data.
20
What is the purpose of a 'proxy server'?
Answer
(C)
To filter network traffic and provide caching.
21
What are the potential drawbacks of using the USB system?
Answer
A
C
D
22
If a single bit error occurs in a data transmission using an even parity scheme, how will it be detected?
Answer
(D)
All of the above.
23
What does the 'payload' in a data packet contain?
Answer
(C)
The actual data being transmitted
24
Which method helps to prevent packets from circulating endlessly in a network?
Answer
(C)
Hop number
25
What is a primary advantage of packet switching?
Answer
(C)
Allows multiple users to share network resources efficiently.
26
In the context of data transmission, what is a 'packet'?
Answer
(B)
A formatted unit of data transmitted over a network.
27
What is the main characteristic of parallel data transmission?
Answer
(B)
Data is transmitted multiple bits at a time over several channels.
28
Which of the following is a function of the 'network layer' in the OSI model?
Answer
(B)
Routing data packets between networks.
29
What is the main difference between Simplex and Half-duplex data transmission modes?
Answer
(B)
Simplex transmits data in one direction only, while half-duplex transmits in both directions, but not simultaneously.
30
What is a 'botnet'?
Answer
(A)
A network of compromised computers controlled by a single attacker.
31
What is the main function of an Automatic Repeat Request (ARQ)?
Answer
(B)
To detect and correct errors that occur during transmission.
32
What is the main advantage of using fiber optic cables for data transmission?
Answer
(B)
Resistance to electrical interference.
33
What best describes the function of an 'Intrusion Detection System (IDS)'?
Answer
(B)
To detect malicious activity and log security events.
34
What is a disadvantage of echo checks?
Answer
(B)
It takes more time to send and receive the data.
35
Which of the following is/are advantage(s) of using USB connection?
Answer
(B)
It is easier to install.
36
What would cause a "time-out" in ARQ?
Answer
(D)
No acknowledgment received within a given period.
37
Which of the following is a main difference between Symmetric and Asymmetric Encryption?
Answer
(B)
Symmetric uses same key for encryption and decryption while Asymmetric uses two different keys.
38
What is the role of a 'gateway' in a network?
Answer
(B)
To act as the entry point to another network.
39
What happens if the receiver detects an error using a checksum?
Answer
(C)
A retransmission is requested.
40
Which of the following are examples of wireless network technologies?
Answer
A
B
41
What is the purpose of a 'MAC address'?
Answer
(A)
To identify a device on a network.
42
What type of error is detectable by a check digit?
Answer
(A)
Errors in data entry
43
What does the term 'payload' refer to in data transmission?
Answer
(B)
The actual data being transmitted.
44
In an ARQ system, what happens if the sender does not receive an acknowledgment (ACK) within a specific time limit?
Answer
(B)
The sender resends the data.
45
What type of checking method is used to make sure that the packets which reaches the destination are complete?
Answer
(C)
Cyclic Redundancy Checks (CRCs)
46
In the context of a network, what action does a router primarily perform?
Answer
(C)
Forwarding data packets based on their destination address.
47
What does the term 'full-duplex' refer to in data transmission?
Answer
(A)
The ability to send and receive data simultaneously.
48
What are the main functions of the data link layer?
Answer
A
C
49
What is the role of a router in a packet-switched network?
Answer
(C)
To determine the best path for a packet.
50
Which of the following is a method for determining data integrity?
Answer
(A)
Check Digits