Computer networking MCQ – Change your future

221. What is the central device in star topology?

Correct Answer: Correct answer is: (B) Hub/switch.

Exam Relevance: CCNA, Network+, CompTIA A+

Difficulty: Easy

Concept notes: In a star topology, all devices connect to a central device, which is typically a hub or a switch.

Common Mistakes: Students may confuse the central device with a router or a server, which are not the primary central devices in a star topology.

Explanations: In a star topology, each device is connected directly to a central hub or switch. This central device acts as a mediator for all messages. The hub or switch ensures that data packets are correctly forwarded to the intended recipient. This configuration simplifies network management and troubleshooting, as each device's connection can be individually isolated and tested.

Option Analysis:

Option A: STP server is not the central device in a star topology. STP (Spanning Tree Protocol) is a protocol used to prevent loops in a network, not a central device.
Option B: Hub/switch is the correct central device in a star topology. It connects all devices and manages data transmission.
Option C: PDC (Primary Domain Controller) is not the central device in a star topology. It is a server role in a network domain.
Option D: Router is not the central device in a star topology. Routers are used to connect different networks, not to manage connections within a single network.

Mnemonic: Hub/switch: "Hub and Switch, Star's Fix"

222. Number of sequences in a Walsh table i.e. N=

Correct Answer: Correct answer is: (C) $2^m$.

Exam Relevance: Digital Communication, Information Theory, Signal Processing

Difficulty: Easy

Concept notes: A Walsh table contains sequences that are used in various digital communication systems. The number of sequences in a Walsh table is determined by the power of 2, specifically $2^m$, where $m$ is the order of the Walsh table.

Common Mistakes: Students may confuse the formula for the number of sequences with other related formulas, such as $2^m - 1$ or $2^m + 1$, which are not applicable in this context.

Explanations: The number of sequences in a Walsh table is given by $2^m$. This is because each sequence in the Walsh table is a unique Hadamard matrix of order $2^m$. The Hadamard matrix is a square matrix with entries of +1 or -1, and the number of such unique sequences is exactly $2^m$.

Option Analysis:

Option A: $2^m + 1$ is incorrect because it does not match the formula for the number of sequences in a Walsh table.
Option B: $2^m - 1$ is incorrect because it does not match the formula for the number of sequences in a Walsh table.
Option C: $2^m$ is the correct formula for the number of sequences in a Walsh table.
Option D: 0 is incorrect because it does not match the formula for the number of sequences in a Walsh table.

223. What is the largest type of WAN?

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

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Easy

Concept notes: The Internet is the largest type of WAN (Wide Area Network) as it connects millions of smaller networks, including LANs (Local Area Networks) and MANs (Metropolitan Area Networks), across the globe.

Common Mistakes: Students may confuse the size of the Internet with other geographical terms like "country" or "continent," which are not types of networks.

Explanations: The Internet is the largest WAN because it spans the entire globe, connecting numerous smaller networks. Other options like "Country," "Continent," and "State" refer to geographical areas and not network types.

Option Analysis:

Option A: The Internet is the largest WAN, connecting millions of smaller networks worldwide.
Option B: "Country" is a geographical term, not a type of network.
Option C: "Continent" is a geographical term, not a type of network.
Option D: "State" is a geographical term, not a type of network.

224. Consider the following Statements: A WAN is a network within one building The lower the latency, the better/faster the connection. Bluetooth network is also known as Wired Personal Area Network Which of the following statement(s) is/are true?

Correct Answer: Correct answer is: (A) Only 2,.

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

Difficulty: Easy

Concept notes: The correct answer is based on the understanding of network types and their characteristics.

Common Mistakes: Students may confuse the definitions of LAN, WAN, and PAN, leading to incorrect identification of network types.

Explanations: Statement 1 is incorrect because a WAN (Wide Area Network) typically spans a large geographical area, not just within one building. Statement 2 is correct as lower latency generally means a faster and more responsive connection. Statement 3 is incorrect because Bluetooth is a wireless technology and thus a Wireless Personal Area Network (WPAN), not a Wired Personal Area Network (WPAN).

Option Analysis:

Option A: Correct, as only statement 2 is true.
Option B: Incorrect, as statement 1 is false.
Option C: Incorrect, as both statements 1 and 3 are false.
Option D: Incorrect, as statement 3 is false.

225. The number of cross point needed for 10 lines in a cross point switch which is full duplex in nature and there are no self connection is

Correct Answer: Correct answer is: (B) 45.

Exam Relevance: Computer Networks, Telecommunications, Switching Theory

Difficulty: Moderate

Concept notes: In a full-duplex cross point switch, each line can connect to any other line, but not to itself. The number of cross points needed is determined by the number of unique connections between the lines.

Common Mistakes: Students often mistakenly calculate the total number of connections including self-connections or double-count connections in a full-duplex switch.

Explanations: For 10 lines, the number of unique connections (cross points) is given by the combination formula $ C(n, 2) $, where $ n $ is the number of lines. This formula calculates the number of ways to choose 2 lines out of 10 without regard to order. The formula is: \[ C(10, 2) = \frac{10 \times 9}{2} = 45 \] This calculation excludes self-connections and avoids double-counting connections in a full-duplex switch.

Option Analysis:

Option A: 100 is incorrect because it would include self-connections and double-count connections.
Option B: 45 is correct as it represents the number of unique connections between 10 lines.
Option C: 50 is incorrect because it does not account for the correct combination formula.
Option D: 90 is incorrect as it would double-count connections.

226. Which of the following network access standard is used for connecting stations to a packet-switched network?

Correct Answer: Correct answer is: (C) X.25.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Moderate

Concept notes: X.25 is a standard for packet-switched network communication, defining the protocols for connecting data terminal equipment (DTE) to a packet-switched network.

Common Mistakes: Students may confuse X.25 with other X-series standards like X.21, which is used for digital communication over a data circuit-terminating equipment (DCE) interface.

Explanations: X.25 is specifically designed for connecting stations to a packet-switched network. It defines the procedures and protocols for data transmission, ensuring reliable communication over a network. This standard is crucial for establishing a connection between a data terminal equipment (DTE) and a packet-switched network, making it the correct choice for this question.

Option Analysis:

Option A: X.3 is a standard for the use of the X.25 packet layer protocol in interworking between public data networks, not for connecting stations to a packet-switched network.
Option B: X.21 is a standard for the interface between data terminal equipment (DTE) and data circuit-terminating equipment (DCE), not for connecting stations to a packet-switched network.
Option C: X.25 is the correct standard for connecting stations to a packet-switched network, defining the protocols for data transmission.
Option D: X.75 is a standard for interworking between X.25 networks, not for connecting stations to a packet-switched network.

Mnemonic: X.25: "X-Connects Stations to Networks"

227. POP3 is a protocol used for..

Correct Answer: Correct answer is: (B) accessing emails.

Exam Relevance: IC3, CompTIA A+, CCNA

Difficulty: Easy

Concept notes: POP3 (Post Office Protocol version 3) is a standard protocol used for retrieving emails from a mail server to a local device.

Common Mistakes: Students may confuse POP3 with SMTP, which is used for sending emails, or with IMAP, which is another protocol for accessing emails but with different functionality.

Explanations: POP3 is specifically designed for downloading emails from a server to a local device. This protocol allows users to access their emails on a single device, typically after downloading them from the server. Once downloaded, the emails are usually removed from the server, unless the user configures the client to leave a copy on the server.

Option Analysis:

Option A: POP3 is not primarily used for reading protocols, but for accessing and downloading emails.
Option B: Correct. POP3 is used for accessing emails by downloading them from a server to a local device.
Option C: POP3 is not specifically designed for downloading images from a server; it is used for emails.
Option D: Sending files is not the primary function of POP3; SMTP is used for sending emails.

228. Which command, when issued in the interface configuration mode of a router, enables the interface to acquire an IPv4 address automatically from an ISP, when that link to the ISP is enabled?

Correct Answer: Correct answer is: (C) Ip address dhcp.

Exam Relevance: CCNA, CompTIA Network+, Cisco certifications

Difficulty: Easy

Concept notes: The command "Ip address dhcp" enables an interface to automatically acquire an IPv4 address from a DHCP server, such as an ISP.

Common Mistakes: Students may confuse "Ip address dhcp" with "Ip dhcp pool," which is used to configure a DHCP pool on the router itself, not to enable the interface to receive an address from an external DHCP server.

Explanations: The command "Ip address dhcp" is used in interface configuration mode to configure the interface to request an IPv4 address from a DHCP server. This is the correct command to enable the interface to automatically acquire an IPv4 address from an ISP when the link is enabled.

Option Analysis:

Option A: "Ip dhcp pool" is used to configure a DHCP pool on the router, not to enable the interface to receive an address from an external DHCP server.
Option B: "Service dhcp" is not a valid command in interface configuration mode. It is used in global configuration mode to enable the DHCP service on the router.
Option C: "Ip address dhcp" is the correct command to enable the interface to automatically acquire an IPv4 address from a DHCP server.
Option D: "Ip helper-address" is used to direct DHCP requests to a DHCP server, but it does not configure the interface to receive an address from the server.

229. Process of transmitting data from one device to another is called

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

Exam Relevance: SAT, ACT, AP Computer Science Principles

Difficulty: Very Easy

Concept notes: The process of transmitting data from one device to another is known as communication.

Common Mistakes: Students may confuse communication with the devices or locations involved in the process, such as data terminals or remote devices.

Explanations: Communication is the process by which data is transmitted from one device to another. It involves the exchange of information between devices, which can be through wired or wireless means. The other options refer to specific devices or locations, not the process of data transmission.

Option Analysis:

Option A: Correct. Communication is the process of transmitting data from one device to another.
Option B: Incorrect. A data terminal is a device used for sending and receiving data, not the process itself.
Option C: Incorrect. Remote refers to a location or device that is distant, not the process of data transmission.
Option D: Incorrect. Locale refers to a specific location or environment, not the process of data transmission.

230. What type of addressing is specifically used by the transport layer?

Correct Answer: Correct answer is: (B) Application program port address.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Moderate

Concept notes: The transport layer is responsible for end-to-end communication between applications, using port numbers to identify specific processes or services.

Common Mistakes: Students often confuse the transport layer addressing with network layer addressing, which uses IP addresses.

Explanations: The transport layer uses port numbers to identify specific applications or services on a host. These port numbers are part of the application program port address, which is used to direct data to the correct application on the receiving host. This addressing scheme is specific to the transport layer and is not used by other layers.

Option Analysis:

Option A: Station address is used at the data link layer to identify devices on a local network.
Option B: Application program port address is used by the transport layer to identify specific applications or services.
Option C: Dialog address is not a standard term in networking and is not used by the transport layer.
Option D: Network address is used at the network layer to identify hosts on a network.

Mnemonic: Port numbers for transport, IP for network.

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Computer networking MCQ - Set 23

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