Computer networking MCQ

931. In transparent bridges, systems administrator would manually enter each table entry during

Correct Answer: Correct answer is: (B) Bridge Setup.

Exam Relevance: CCNA, Network+, CompTIA Network+

Difficulty: Moderate

Concept notes: In transparent bridges, the administrator manually configures the bridge's forwarding table during the bridge setup phase.

Common Mistakes: Students may confuse the setup phase with data or frame setup phases, where the bridge typically learns dynamically.

Explanations: During the bridge setup phase, a systems administrator manually enters each table entry. This is a critical step in configuring the bridge to ensure it forwards frames correctly between different network segments. The manual entry ensures that the bridge has the necessary information to make forwarding decisions without relying on dynamic learning, which can be less reliable in certain network configurations.

Option Analysis:

Option A: Data Setup is incorrect because data setup typically involves the transmission of data, not the configuration of the bridge's forwarding table.
Option B: Bridge Setup is correct because this phase involves manually configuring the bridge's forwarding table.
Option C: Frame Setup is incorrect because frame setup pertains to the structure and format of frames, not the configuration of the bridge.
Option D: Packages Setup is incorrect because package setup is not a standard phase in bridge configuration.

Mnemonic: Bridge Setup, Manual Entry

932. Line coding, block coding and scrambling are techniques of converting the

Correct Answer: Correct answer is: (B) Digital data to digital signals.

Exam Relevance: GATE, IEEE, ECE exams

Difficulty: Moderate

Concept notes: Line coding, block coding, and scrambling are techniques used in digital communication to convert digital data into digital signals for transmission over a communication channel.

Common Mistakes: Students may confuse these techniques with analog-to-digital conversion methods, which are not applicable here.

Explanations: Line coding, block coding, and scrambling are methods used to encode digital data into a form suitable for transmission over a digital communication channel. These techniques ensure that the digital data can be accurately transmitted and received without loss or corruption. Line coding converts the binary data into a signal that can be transmitted over a physical medium. Block coding adds redundancy to the data to detect and correct errors. Scrambling is used to prevent long sequences of the same bit value, which can cause issues in transmission. Therefore, these techniques are specifically used to convert digital data into digital signals.

Option Analysis:

Option A: Incorrect because line coding, block coding, and scrambling do not convert analog data to analog signals. These techniques are used for digital data.
Option B: Correct because these techniques are used to convert digital data into digital signals for transmission.
Option C: Incorrect because these techniques do not convert analog data to digital signals. They are used for digital data.
Option D: Incorrect because these techniques do not convert digital signals to digital data. They convert digital data to digital signals.

933. A topology that involves Tokens.

Correct Answer: Correct answer is: (B) Ring.

Exam Relevance: Computer Networks, Data Communications, Network Fundamentals

Difficulty: Moderate

Concept notes: In a ring topology, data is transmitted using tokens.

Common Mistakes: Students may confuse the token passing mechanism with other topologies like bus or star, which do not use tokens.

Explanations: In a ring topology, each device is connected to two other devices, forming a closed loop. Data is transmitted in a circular path, and a token is used to control access to the network. Only the device holding the token can transmit data, ensuring that data packets are not lost or corrupted due to collisions. This token-passing mechanism is a defining feature of the ring topology.

Option Analysis:

Option A: Star topology does not use tokens. In a star topology, all devices are connected to a central hub or switch, and data transmission is managed by the central device.
Option B: Ring topology uses tokens to control data transmission. This is the correct answer.
Option C: Bus topology does not use tokens. In a bus topology, all devices are connected to a single communication line, and data is broadcast to all devices on the line.
Option D: Daisy chaining is a method of connecting devices in a series, but it does not specifically involve tokens for data transmission.

Mnemonic: Ring = Token

934. The maximum throughput for pure ALOHA is..... per cent.

Correct Answer: Correct answer is: (B) 18.4.

Exam Relevance: Computer Networks, Data Communications, Network Fundamentals

Difficulty: Moderate

Concept notes: The maximum throughput for pure ALOHA is a key concept in understanding the efficiency of this random access protocol in computer networks.

Common Mistakes: Students often confuse the maximum throughput of pure ALOHA with that of slotted ALOHA, which is higher.

Explanations: In pure ALOHA, the maximum throughput is given by the formula \( G \times e^{-2G} \), where \( G \) is the offered load. The maximum value of this function occurs when \( G = 0.5 \). Substituting \( G = 0.5 \) into the formula yields \( 0.5 \times e^{-1} \approx 0.184 \) or 18.4%.

Option Analysis:

Option A: 12.2 is incorrect as it does not match the calculated maximum throughput for pure ALOHA.
Option B: 18.4 is the correct value for the maximum throughput of pure ALOHA.
Option C: 36.8 is incorrect as it is the maximum throughput for slotted ALOHA, not pure ALOHA.
Option D: None of the above is incorrect as 18.4 is a valid option.

935. In Global Service for Mobile (GSM), each band is 25 MHz in width, shifted toward

Correct Answer: Correct answer is: (D) 900 MHz.

Exam Relevance: GATE, GRE, Professional Certification Exams

Difficulty: Easy

Concept notes: In the Global System for Mobile Communications (GSM), the primary frequency band used is centered around 900 MHz. Each band is 25 MHz wide and is shifted towards this frequency.

Common Mistakes: Students may confuse the frequency bands with other mobile communication systems or may not be familiar with the specific frequency range used in GSM.

Explanations: The GSM system operates in various frequency bands, but the most commonly used and well-known band is centered around 900 MHz. Each band is 25 MHz wide, and the 900 MHz band is a standard reference point for GSM operations. This makes 900 MHz the correct answer.

Option Analysis:

Option A: 400 MHz is not a standard frequency band for GSM operations.
Option B: 650 MHz is not a standard frequency band for GSM operations.
Option C: 750 MHz is not a standard frequency band for GSM operations.
Option D: 900 MHz is the correct frequency band for GSM operations.

Mnemonic: GSM 900, Think 900 MHz.

936. Speed of transmitted data is measured by

Correct Answer: Correct answer is: (A) Baud.

Exam Relevance: GATE, ECE, Computer Science Exams

Difficulty: Easy

Concept notes: Baud is a unit of measurement for the rate of data transmission over a communication channel.

Common Mistakes: Students may confuse baud with bits per second, which is a related but distinct measure.

Explanations: Baud measures the number of signal changes per second, which can be used to determine the speed of data transmission. It is a fundamental unit in telecommunications and digital communication systems.

Option Analysis:

Option A: Baud is the correct unit for measuring the speed of transmitted data.
Option B: Band is not a unit of measurement for data transmission speed.
Option C: Hertz measures frequency, not data transmission speed.
Option D: Seconds is a unit of time, not a measure of data transmission speed.

Mnemonic: Baud is the "beat" of data transmission.

937. Router sends a prune message to upstream router so that it can exclude corresponding

Correct Answer: Correct answer is: (C) Interface.

Exam Relevance: CCNA, CCNP, JNCIA, JNCIS

Difficulty: Moderate

Concept notes: In multicast routing, a prune message is used to stop the flow of multicast traffic on a specific interface.

Common Mistakes: Students may confuse the purpose of a prune message with stopping traffic from a source or protocol, rather than an interface.

Explanations: A prune message is sent by a router to its upstream router to indicate that it does not want to receive multicast traffic on a specific interface. This helps in optimizing the multicast traffic flow by preventing unnecessary traffic from being forwarded on interfaces where it is not needed.

Option Analysis:

Option A: A prune message does not exclude a source, but rather stops traffic on a specific interface.
Option B: A prune message does not exclude a protocol, but rather stops traffic on a specific interface.
Option C: A prune message is used to stop traffic on a specific interface, making this the correct answer.
Option D: A prune message does not exclude information, but rather stops traffic on a specific interface.

938. Internet Protocol version 4 (IPv4) delivery mechanism is used by

Correct Answer: Correct answer is: (B) TCP/IP protocols.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Easy

Concept notes: The Internet Protocol version 4 (IPv4) is a core component of the TCP/IP protocol suite, which is used for delivering data packets over the internet.

Common Mistakes: Students may confuse IPv4 with other protocols or standards, such as IEEE protocols, which are not directly related to internet data delivery.

Explanations: IPv4 is part of the TCP/IP protocol suite, which is the standard for internet communication. The TCP/IP protocols include a suite of protocols designed to ensure reliable data transmission over the internet. IPv4 is responsible for addressing and routing packets of data between devices on the internet. Therefore, the delivery mechanism of IPv4 is inherently tied to the TCP/IP protocols.

Option Analysis:

Option A: IEEE protocols are not directly related to internet data delivery mechanisms.
Option B: TCP/IP protocols include IPv4, which is used for internet data delivery.
Option C: Internet protocols is a broad term and not specific enough to identify the correct delivery mechanism.
Option D: UDP is a transport layer protocol and not the delivery mechanism for IPv4.

939. Bridges are used at..... layer.

Correct Answer: Correct answer is: (B) MAC layer.

Exam Relevance: CCNA, CompTIA Network+, CIW Network Specialist

Difficulty: Moderate

Concept notes: Bridges operate at the Data Link layer of the OSI model, which includes the MAC sublayer.

Common Mistakes: Students often confuse bridges with switches, which also operate at the Data Link layer, but bridges specifically refer to devices that operate at the MAC sublayer.

Explanations: Bridges are used to connect multiple network segments at the Data Link layer, specifically at the MAC sublayer. They use MAC addresses to make forwarding decisions, filtering and forwarding frames based on the destination MAC address. This function is distinct from physical layer devices like repeaters and network layer devices like routers.

Option Analysis:

Option A: Bridges do not operate at the Physical layer, which deals with the transmission and reception of raw bit streams over a physical medium.
Option B: Bridges operate at the MAC sublayer of the Data Link layer, making this the correct answer.
Option C: Network layer devices, such as routers, operate at a higher layer and use IP addresses for routing decisions.
Option D: Transport layer devices, such as TCP and UDP, operate at a higher layer and are responsible for end-to-end communication.

Mnemonic: MAC Bridge: "MAC" for Media Access Control, the sublayer where bridges operate.

940. When the IP layer of a receiving host receives a datagra, M.....

Correct Answer: Correct answer is: (B) A transport layer protocol takes over.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Moderate

Concept notes: The IP layer is responsible for routing and delivering packets to the correct destination. Once the packet reaches the destination, the transport layer protocol (such as TCP or UDP) takes over to handle the delivery of the data to the appropriate application.

Common Mistakes: Students may mistakenly believe that delivery is complete once the packet reaches the destination, not realizing that further processing by the transport layer is necessary.

Explanations: When a datagram reaches the receiving host, the IP layer is responsible for ensuring the packet has arrived at the correct destination. However, the IP layer does not handle the final delivery to the application. Instead, the transport layer protocol, such as TCP or UDP, takes over to ensure reliable delivery and to pass the data to the appropriate application. This is why the correct answer is that a transport layer protocol takes over.

Option Analysis:

Option A: This is incorrect because delivery is not complete at the IP layer; further processing by the transport layer is required.
Option B: This is correct because the transport layer protocol takes over to handle the final delivery to the application.
Option C: This is incorrect because adding a header is not the next step; the transport layer takes over.
Option D: This is incorrect because one of the other options is correct.

Mnemonic: IP to Transport, Take Over (ITT)

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Computer networking MCQ - Set 94

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