Computer networking MCQ – Change your future

201. Which command will show you whether a DTE or a DCE cable is plugged into serial 0?

Correct Answer: Correct answer is: (C) Show controllers serial 0.

Exam Relevance: CCNA, CCNP, Network+

Difficulty: Moderate

Concept notes: The command "show controllers serial 0" is used to display information about the serial interface, including whether a DTE or DCE cable is connected.

Common Mistakes: Students may mistakenly use "show interfaces" commands, which do not provide the specific information about the cable type.

Explanations: The "show controllers serial 0" command provides detailed information about the serial interface, including the type of cable connected (DTE or DCE). This command is specifically designed to give hardware-related details, which is why it is the correct choice for identifying the cable type.

Option Analysis:

Option A: The "sh int s0" command shows interface status and statistics but does not provide information about the cable type.
Option B: The "sh int serial 0" command is similar to Option A and does not provide information about the cable type.
Option C: The "show controllers serial 0" command is the correct choice as it provides hardware-related details, including the cable type.
Option D: The "show serial 0 controllers" command is not a valid command and will not provide the required information.

202. FTP is built on..... architecture

Correct Answer: Correct answer is: (A) Client-server.

Exam Relevance: Networking exams, Computer Science exams, IT certifications

Difficulty: Easy

Concept notes: FTP (File Transfer Protocol) operates on a client-server architecture.

Common Mistakes: Students may confuse FTP with P2P (Peer-to-Peer) networks, which do not involve a central server.

Explanations: FTP is designed to transfer files between a client and a server. The client initiates the request to download or upload files, and the server responds to these requests. This interaction is characteristic of a client-server architecture, where one entity (the server) provides services to another (the client).

Option Analysis:

Option A: Correct. FTP uses a client-server model where the client requests files from the server.
Option B: Incorrect. FTP does not use a P2P architecture, which involves direct communication between peers without a central server.
Option C: Incorrect. FTP exclusively uses a client-server model, not a combination of client-server and P2P.
Option D: Incorrect. FTP is a well-defined protocol that operates on a client-server architecture.

203. The process of keeping addresses in memory for future use is called

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

Exam Relevance: Computer Science, Networking, Operating Systems

Difficulty: Easy

Concept notes: Caching is the process of storing data in a temporary storage area for quick access in the future.

Common Mistakes: Students may confuse caching with routing, which is the process of determining the path for data to travel across a network.

Explanations: Caching involves keeping addresses in memory to speed up future access. This is a common technique used in computer systems to improve performance by reducing the need to fetch data from slower storage repeatedly.

Option Analysis:

Option A: Routing is the process of determining the best path for data to travel across a network, not storing addresses for future use.
Option B: Resolving typically refers to the process of converting a domain name to an IP address, not storing addresses in memory.
Option C: Caching is the correct term for storing addresses in memory for future use.
Option D: None of the above is incorrect because caching is the correct term.

Mnemonic: Cache = Keep it close for quick recall.

204. SYNC flooding attack belongs to a type of security attack known as

Correct Answer: Correct answer is: (D) Denial-of-service attack.

Exam Relevance: CISSP, CompTIA Security+, CEH

Difficulty: Moderate

Concept notes: A denial-of-service (DoS) attack is a type of cyber attack where the attacker aims to make a service unavailable to its intended users by overwhelming the service with traffic or requests.

Common Mistakes: Students may confuse a SYN flood attack with a passive attack, which does not involve sending malicious traffic but rather involves monitoring and eavesdropping on network traffic.

Explanations: A SYN flood attack is a specific type of denial-of-service attack where the attacker sends a large number of SYN (synchronize) requests to a server, overwhelming it and preventing legitimate users from accessing the service. This makes it a form of DoS attack.

Option Analysis:

Option A: This is a restatement of the question and not a type of attack.
Option B: An active attack involves direct interaction with the system, but it is a broader category that includes DoS attacks.
Option C: A passive attack involves monitoring and eavesdropping, not sending malicious traffic.
Option D: A SYN flood attack is a specific type of DoS attack, making this the correct answer.

Mnemonic: SYN flood = Service Yanked, Not functional

205. The..... cellular phone system will provide universal personal communication.

Correct Answer: Correct answer is: (C) Third-generation.

Exam Relevance: GATE, ECE, Telecommunications Engineering Exams

Difficulty: Moderate

Concept notes: The third-generation (3G) cellular phone system was designed to provide universal personal communication services, including high-speed data transmission and multimedia support.

Common Mistakes: Students may confuse the capabilities of different generations of cellular technology, particularly the distinctions between 2G and 3G.

Explanations: The third-generation (3G) cellular phone system was specifically developed to offer advanced features such as high-speed data transmission, video calls, and multimedia services. This generation of cellular technology was designed to support a wide range of applications beyond voice and text messaging, enabling universal personal communication. The 3G system provides the necessary infrastructure to support these advanced services, making it the correct answer.

Option Analysis:

Option A: First-generation cellular systems were primarily focused on voice communication and lacked the advanced data capabilities of later generations.
Option B: Second-generation systems introduced digital voice and text messaging but did not fully support the high-speed data and multimedia services required for universal personal communication.
Option C: Third-generation systems were designed to provide high-speed data transmission and multimedia support, enabling universal personal communication.
Option D: This option is incorrect as the third-generation system is the correct answer.

Mnemonic: 3G for Global Communication

206. Sequence numbers of Stop-and-Wait Automatic Repeat Request are based on

Correct Answer: Correct answer is: (B) Modulo-2 arithmetic.

Exam Relevance: Computer Networks, Data Communication, Network Protocols

Difficulty: Moderate

Concept notes: In Stop-and-Wait Automatic Repeat Request (ARQ), sequence numbers are used to identify frames. These sequence numbers are typically based on modulo-2 arithmetic, which simplifies the implementation of the protocol by using binary values (0 and 1) to manage the sequence of frames.

Common Mistakes: Students often confuse the use of modulo-2 arithmetic with simple arithmetic, which does not account for the binary nature of the sequence numbers in ARQ protocols.

Explanations: Sequence numbers in Stop-and-Wait ARQ are based on modulo-2 arithmetic because it allows for the use of binary values (0 and 1) to represent the sequence of frames. This simplifies the protocol by enabling the receiver to easily determine if a frame is new or a duplicate by checking the sequence number modulo 2. This binary system ensures that only two sequence numbers are needed, making the protocol straightforward and efficient.

Option Analysis:

Option A: Simple arithmetic does not account for the binary nature of sequence numbers in ARQ protocols.
Option B: Modulo-2 arithmetic is correct because it uses binary values (0 and 1) to manage the sequence of frames, simplifying the protocol.
Option C: Logical arithmetic is not specific to the binary sequence management used in ARQ protocols.
Option D: Modular multiplicative inverse is not relevant to the sequence number management in ARQ protocols.

Mnemonic: Modulo-2, Binary, 0-1

207. The maximum size of the TCP header is

Correct Answer: Correct answer is: (C) 60 bytes.

Exam Relevance: Computer Networks, CCNA, CISSP

Difficulty: Moderate

Concept notes: The TCP header can vary in size due to the presence of optional fields, such as options. The maximum size of the TCP header is 60 bytes.

Common Mistakes: Students often confuse the minimum size of the TCP header (20 bytes) with the maximum size.

Explanations: The TCP header consists of a mandatory 20-byte section and an optional section for options. The maximum size of the TCP header is 60 bytes, which includes the 20-byte mandatory section and up to 40 bytes of options. This maximum size is achieved when the options field is fully utilized.

Option Analysis:

Option A: 20 bytes is the minimum size of the TCP header, not the maximum.
Option B: 40 bytes is not the maximum size of the TCP header.
Option C: 60 bytes is the correct maximum size of the TCP header.
Option D: 80 bytes exceeds the maximum size of the TCP header.

208. A basic service set without an access point is a stand alone network called

Correct Answer: Correct answer is: (C) Adhoc network.

Exam Relevance: Computer Networks, Wireless Communication, Network Fundamentals

Difficulty: Easy

Concept notes: A basic service set without an access point is known as an ad hoc network. In an ad hoc network, devices communicate directly with each other without the need for a central access point.

Common Mistakes: Students may confuse ad hoc networks with infrastructure networks, which require an access point for communication.

Explanations: An ad hoc network is a decentralized type of wireless network where devices communicate directly with each other without the need for a central access point. This is in contrast to an infrastructure network, which requires an access point to facilitate communication between devices. Therefore, a basic service set without an access point is correctly identified as an ad hoc network.

Option Analysis:

Option A: A cellular network is a type of mobile network that uses cell sites to provide wireless coverage. It is not related to the concept of a basic service set without an access point.
Option B: A point-to-point network is a simple network that connects two devices directly. While it does not use an access point, it is not the same as an ad hoc network, which can involve multiple devices.
Option C: An ad hoc network is a decentralized network where devices communicate directly without an access point, matching the description of a basic service set without an access point.
Option D: An infrastructure network requires an access point to facilitate communication between devices, which is the opposite of the scenario described.

209. Protocol Independent Multicast (PIM) has two independent multicast Protocols, those are

Correct Answer: Correct answer is: (D) PIM-DM and PIM-SM.

Exam Relevance: CCNA, CCNP, JNCIA, JNCIS

Difficulty: Moderate

Concept notes: Protocol Independent Multicast (PIM) is a routing protocol used for multicast traffic in IP networks. It has two main modes of operation: PIM-DM (Dense Mode) and PIM-SM (Sparse Mode).

Common Mistakes: Students may confuse PIM-DM and PIM-SM with other acronyms or modes that are not part of the PIM protocol.

Explanations: PIM-DM operates under the assumption that all routers in the network are interested in receiving multicast traffic. It floods multicast traffic to all routers and then prunes back the unnecessary traffic. PIM-SM, on the other hand, assumes that only a few routers are interested in multicast traffic. It uses a shared tree and a source-specific tree to efficiently deliver multicast traffic to interested receivers.

Option Analysis:

Option A: Incorrect. PIM-DS is not a recognized mode of PIM.
Option B: Incorrect. PIM-DR is not a recognized mode of PIM.
Option C: Incorrect. PIM-DL is not a recognized mode of PIM.
Option D: Correct. PIM-DM and PIM-SM are the two recognized modes of PIM.

Mnemonic: PIM-DM: Dense Mode, PIM-SM: Sparse Mode

210. We cannot send digital signal directly to channel, when channel is

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

Exam Relevance: GATE, ECE, EE

Difficulty: Moderate

Concept notes: Digital signals are typically baseband signals, meaning they occupy a low frequency range. Bandpass channels, on the other hand, operate at higher frequencies and require the digital signal to be modulated to fit within the channel's frequency range.

Common Mistakes: Students may confuse baseband and bandpass channels, leading to incorrect selection of baseband as the answer.

Explanations: Digital signals are inherently baseband signals, which means they occupy a low frequency range. Bandpass channels, however, operate at higher frequencies and require the signal to be modulated to fit within the channel's frequency range. Therefore, digital signals cannot be sent directly to a bandpass channel without modulation.

Option Analysis:

Option A: Correct. Bandpass channels require modulation of the digital signal to fit within the channel's frequency range.
Option B: Incorrect. "Bypass" is not a standard term for channel types in this context.
Option C: Incorrect. Baseband channels can directly transmit digital signals without modulation.
Option D: Incorrect. Low pass channels can also directly transmit digital signals without modulation.

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Computer networking MCQ - Set 21

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