Computer networking MCQ

1091. You set the console password, but when you display the configuration, the password doesn't show up; it looks like this: [output cut] Line console 0 Exec-timeout 1 44 Password 7098C0BQR Login [output cut] What cause the password to be stored like this?

Correct Answer: Correct answer is: (B) Service password-encryption.

Exam Relevance: CCNA, CCNP, CCIE

Difficulty: Moderate

Concept notes: The command "service password-encryption" is used to encrypt all passwords in the configuration of a Cisco device. This ensures that passwords are not stored in plain text, enhancing security.

Common Mistakes: Students often confuse the command with "service-password-encryption" (without the space), which is not a valid command.

Explanations: The command "service password-encryption" encrypts all passwords in the configuration. When this command is enabled, passwords are stored in an encrypted format, which is why the password appears as "7098C0BQR" instead of plain text. This encryption is a security measure to prevent unauthorized access to the device configuration.

Option Analysis:

Option A: Encrypt password is not a valid command on Cisco devices.
Option B: Service password-encryption is the correct command to encrypt all passwords in the configuration.
Option C: Service-password-encryption is not a valid command; the correct command is "service password-encryption" with a space.
Option D: Exec-timeout 1 35 is unrelated to password encryption and only sets the console timeout.

1092. Dual cable and signal cable are the two types of

Correct Answer: Correct answer is: (A) Broadband networks.

Exam Relevance: Computer Networks, Telecommunications, Network Engineering

Difficulty: Moderate

Concept notes: Broadband networks support high-speed data transmission and can carry multiple signals simultaneously over a single cable. Dual cable and signal cable are types of broadband network configurations.

Common Mistakes: Students may confuse broadband networks with baseband networks, which use a single channel for data transmission and do not support multiple signals simultaneously.

Explanations: Broadband networks are designed to carry multiple signals over a single cable, which is why dual cable and signal cable configurations are used. These configurations allow for the simultaneous transmission of different types of data, such as voice, video, and internet traffic, over a single cable. This capability distinguishes broadband networks from baseband networks, which are limited to a single channel for data transmission.

Option Analysis:

Option A: Correct. Dual cable and signal cable are types of configurations used in broadband networks.
Option B: Incorrect. Radio networks typically use wireless communication and do not involve cable configurations.
Option C: Incorrect. Baseband networks use a single channel for data transmission and do not support multiple signals simultaneously.
Option D: Incorrect. Satellite networks use wireless communication and do not involve cable configurations.

Mnemonic: Broadband: "B" for "Broad" and "B" for "Bandwidth" - think "Broad" range of signals.

1093. *Session layer

Correct Answer: Correct answer is: (D) -Responsible for establishing "sessions" between users.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Moderate

Concept notes: The session layer is part of the OSI model and is responsible for establishing, managing, and terminating sessions between applications.

Common Mistakes: Students often confuse the session layer with the presentation layer, which deals with data representation and encryption.

Explanations: The session layer is responsible for establishing, managing, and terminating sessions between applications. It ensures that communication between applications is maintained and that data is transferred correctly. This layer is crucial for maintaining the continuity of communication and managing the flow of data between applications.

Option Analysis:

Option A: Incorrect. The network layer is responsible for routing and forwarding data packets, not session establishment.
Option B: Incorrect. The presentation layer is responsible for data representation, encryption, and compression.
Option C: Incorrect. The application layer is the highest layer in the OSI model and deals with user applications and services.
Option D: Correct. The session layer is responsible for establishing, managing, and terminating sessions between applications.

Mnemonic: S - Session, S - Sessions, S - Start, S - Stop

1094. Distributed Queue Dual Bus is a standard for

Correct Answer: Correct answer is: (D) LAN and MAN.

Exam Relevance: Computer Networks, Data Communication, Network Engineering

Difficulty: Moderate

Concept notes: Distributed Queue Dual Bus (DQDB) is a standard for high-speed data transmission in both Local Area Networks (LANs) and Metropolitan Area Networks (MANs).

Common Mistakes: Students may mistakenly believe DQDB is only applicable to LANs, overlooking its use in MANs.

Explanations: DQDB is designed to support high-speed data transmission in both LANs and MANs. It uses a dual bus architecture to provide efficient and reliable communication. The dual bus structure allows for load balancing and redundancy, making it suitable for both LAN and MAN environments. Therefore, the correct answer is that DQDB is a standard for LAN and MAN.

Option Analysis:

Option A: Incorrect, as DQDB is not limited to LANs.
Option B: Incorrect, as DQDB is not a standard for WANs.
Option C: Incorrect, as DQDB is not a standard for Wireless LANs.
Option D: Correct, as DQDB is a standard for both LAN and MAN.

Mnemonic: DQDB: Dual Bus for LAN and MAN

1095. In a computer, number of times a wave repeats during a specific time interval is called its

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

Exam Relevance: Physics, AP Physics, SAT Subject Test in Physics

Difficulty: Easy

Concept notes: Frequency is the number of times a wave repeats itself in a given time interval, typically measured in Hertz (Hz).

Common Mistakes: Students may confuse frequency with amplitude, which is the height of the wave, or with pulse, which is a single wave cycle.

Explanations: Frequency is defined as the number of wave cycles that occur in one second. It is a measure of how often a wave repeats itself over time. This makes it the correct term for describing the number of times a wave repeats during a specific time interval.

Option Analysis:

Option A: Pulse refers to a single wave cycle, not the number of cycles per second.
Option B: Amplitude refers to the height of the wave, not the number of cycles per second.
Option C: Frequency is the correct term for the number of wave cycles per second.
Option D: Oscillation refers to the back-and-forth movement of a wave, not the number of cycles per second.

1096. Multiple users share a common channel is called.....

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

Exam Relevance: Computer Networks, Data Communications, Network Fundamentals

Difficulty: Moderate

Concept notes: Contention refers to a situation where multiple users share a common communication channel, leading to potential conflicts when more than one user attempts to transmit data simultaneously.

Common Mistakes: Students may confuse contention with other network protocols or concepts, such as CSMA/CD, which is a specific protocol used to manage contention in Ethernet networks.

Explanations: Contention is the correct term for a scenario where multiple users share a common channel. In such a scenario, users compete for access to the channel, which can lead to collisions if two or more users attempt to transmit data at the same time. This concept is fundamental in understanding how shared media networks operate and manage access.

Option Analysis:

Option A: LAN (Local Area Network) refers to a network that connects computers within a limited area, such as a home, school, or office building. It does not specifically describe the scenario of multiple users sharing a common channel.
Option B: WAN (Wide Area Network) refers to a network that spans a large geographical area, such as different cities or countries. It does not describe the scenario of multiple users sharing a common channel.
Option C: Contention is the correct term for the scenario where multiple users share a common channel and compete for access.
Option D: CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is a protocol used in Ethernet networks to manage contention by detecting and handling collisions. While it is related to contention, it is not the term that describes the scenario itself.

1097. What are two functions of intermediary devices on a network? (Choose two.)

Correct Answer: Correct answer is: (D) Only (A) & (B).

Exam Relevance: CCNA, Network+, CISSP

Difficulty: Moderate

Concept notes: Intermediary devices on a network perform various functions, including directing data along alternate pathways when there is a link failure and filtering the flow of data based on security settings.

Common Mistakes: Students may mistakenly believe that intermediary devices are the primary source and providers of information and services to end devices, which is a role typically performed by servers or other end devices.

Explanations: Intermediary devices, such as routers and switches, are responsible for directing data along alternate pathways when there is a link failure. This ensures that data can still reach its destination even if the primary path is unavailable. Additionally, these devices can filter the flow of data based on security settings, such as firewalls, to prevent unauthorized access and protect the network. Option C is incorrect because intermediary devices do not provide information and services; they facilitate the flow of data between end devices and servers.

Option Analysis:

Option A: Correct. Intermediary devices can direct data along alternate pathways when there is a link failure.
Option B: Correct. Intermediary devices can filter the flow of data based on security settings.
Option C: Incorrect. Intermediary devices do not provide information and services; they facilitate data flow.
Option D: Correct. Only options A and B are correct functions of intermediary devices.

1098. In NRZ-I inversion or lack of inversion determines the

Correct Answer: Correct answer is: (B) Value of the bits.

Exam Relevance: Computer Networks, Digital Communications, Data Transmission

Difficulty: Easy

Concept notes: In NRZ-I encoding, the value of each bit is determined by whether there is an inversion or not.

Common Mistakes: Students may confuse NRZ-I with other encoding schemes where the value of bytes or frames might be determined differently.

Explanations: In NRZ-I (Non-Return-to-Zero Inverted) encoding, the value of each bit is determined by the presence or absence of a transition (inversion) at the beginning of the bit period. A '1' bit is represented by a transition, while a '0' bit is represented by no transition. Therefore, the value of the bits is directly determined by whether there is an inversion or not.

Option Analysis:

Option A: Incorrect because NRZ-I does not determine the value of bytes, only bits.
Option B: Correct because NRZ-I encoding uses transitions to represent the value of bits.
Option C: Incorrect because NRZ-I does not determine the status of frames.
Option D: Incorrect because the correct answer is provided.

1099. Each block in class A contains..... addresses.

Correct Answer: Correct answer is: (B) $2^{24}$

Exam Relevance: CCNA, Network+, CISSP

Difficulty: Moderate

Concept notes: In networking, the number of addresses in a block is determined by the size of the block. Class A addresses are defined to have a block size that allows for $2^{24}$ addresses.

Common Mistakes: Students often confuse the block sizes of different classes, leading to errors in calculating the number of addresses.

Explanations: Class A addresses are defined to have the first bit set to 0, allowing for 7 bits for the network portion and 24 bits for the host portion. Therefore, the number of addresses in a Class A block is $2^{24}$.

Option Analysis:

Option A: Incorrect, as $2^{16}$ is the number of addresses in a Class B block.
Option B: Correct, as $2^{24}$ is the number of addresses in a Class A block.
Option C: Incorrect, as $2^8$ is the number of addresses in a Class C block.
Option D: Incorrect, as $2^{14}$ does not correspond to any standard class block size.

Mnemonic: A for All, 24 for the host part.

1100. Which one of the following statements is FALSE?

Correct Answer: Correct answer is: (B) Packet switching results in less variation in delay than circuit switching.

Exam Relevance: Computer Networks, Data Communications, Network Fundamentals

Difficulty: Moderate

Concept notes: In packet switching, packets may take different routes to reach their destination, leading to variable delays. In contrast, circuit switching establishes a dedicated path with consistent delay.

Common Mistakes: Students may incorrectly assume that packet switching, due to its dynamic nature, results in more consistent delays compared to the fixed path of circuit switching.

Explanations: Packet switching involves breaking data into packets that travel independently through the network. Each packet may take a different route, leading to variations in delay. In circuit switching, a dedicated path is established for the duration of the communication, resulting in more consistent delay times. Therefore, packet switching does not result in less variation in delay compared to circuit switching.

Option Analysis:

Option A: Packet switching indeed leads to better bandwidth utilization as it allows multiple communications to share the same link.
Option B: Packet switching results in more variation in delay due to the independent routing of packets.
Option C: Packet switching requires more processing per packet due to the need for addressing, routing, and reassembly.
Option D: Packet switching can lead to reordering of packets, unlike circuit switching where packets follow a fixed path.

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Computer networking MCQ - Set 110

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