Computer networking MCQ

1951. Which router command allows you to view the entire contents of all access lists?

Correct Answer: Correct answer is: (B) Show access-lists.

Exam Relevance: CCNA, CCNP, Network+

Difficulty: Easy

Concept notes: The command "show access-lists" is used to display the entire contents of all access lists configured on a router.

Common Mistakes: Students may mistakenly use "show all access-lists" or "show ip interface" which do not provide the complete access list information.

Explanations: The command "show access-lists" is the correct command to view the entire contents of all access lists on a router. This command provides a comprehensive view of all configured access lists, including their rules and settings.

Option Analysis:

Option A: "show all access-lists" is not a valid command and will not display the access lists.
Option B: "show access-lists" is the correct command to view all access lists.
Option C: "show ip interface" displays information about the IP interfaces, not the access lists.
Option D: "show interface" displays information about the interfaces, not the access lists.

1952. Well-known port used for FTP's control connection is

Correct Answer: Correct answer is: (D) Port 21.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Easy

Concept notes: FTP (File Transfer Protocol) uses two ports: one for control connections and one for data transfers. The control connection uses port 21, while the data transfer can use port 20 or another dynamically assigned port.

Common Mistakes: Students often confuse the port numbers for control and data connections in FTP.

Explanations: FTP's control connection uses port 21. This port is used for sending commands and receiving responses between the FTP client and server. Port 20 is used for data transfer, not for control connections.

Option Analysis:

Option A: Port 6 is not used for FTP control connections.
Option B: Port 8 is not used for FTP control connections.
Option C: Port 20 is used for FTP data transfer, not control connections.
Option D: Port 21 is the correct port for FTP control connections.

Mnemonic: FTP Control: 21, Data: 20

1953. If value of sub field type is 1100 in control frames, then it contains information of

Correct Answer: Correct answer is: (B) Clear to send.

Exam Relevance: GATE, GRE, CCNA

Difficulty: Moderate

Concept notes: In control frames, the subfield type 1100 specifically indicates the Clear to Send (CTS) frame. This frame is used in wireless communication to acknowledge the receipt of a Request to Send (RTS) frame and to inform the sender that the channel is clear for data transmission.

Common Mistakes: Students often confuse the subfield types for different control frames, such as RTS and CTS, leading to incorrect identification of the frame type.

Explanations: The subfield type 1100 in control frames corresponds to the Clear to Send (CTS) frame. This frame is used in wireless communication protocols to indicate that the receiver is ready to receive data and that the channel is clear. It is typically sent in response to a Request to Send (RTS) frame, which is used to request permission to transmit data. The CTS frame ensures that the channel is free from interference and that the sender can proceed with the data transmission.

Option Analysis:

Option A: Request to send (RTS) is a different control frame type, not 1100.
Option B: Clear to send (CTS) is the correct frame type for subfield 1100.
Option C: Acknowledgement (ACK) is another control frame type, not 1100.
Option D: Sender is not a frame type but refers to the entity sending the frame.

1954. What are the four TCP/IP Layers?

Correct Answer: Correct answer is: (A) Application > Transport > Internet/Network > Link.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Easy

Concept notes: The TCP/IP model consists of four layers: Application, Transport, Internet/Network, and Link. Each layer has specific functions and responsibilities in the communication process.

Common Mistakes: Students often confuse the order of the layers, particularly the position of the Transport and Internet/Network layers.

Explanations: The correct order of the TCP/IP layers is Application, Transport, Internet/Network, and Link. The Application layer is the topmost layer and deals with software applications. The Transport layer handles end-to-end communication between hosts. The Internet/Network layer is responsible for routing packets across networks. The Link layer deals with the physical transmission of data over a network medium.

Option Analysis:

Option A: This is the correct order of the TCP/IP layers.
Option B: This order is incorrect as it places the Transport layer above the Application layer.
Option C: This order is incorrect as it places the Link layer at the top and the Application layer at the bottom.
Option D: This order is incorrect as it places the Internet/Network layer between the Application and Transport layers.

Mnemonic: ATIL: Application, Transport, Internet, Link

1955. Which two tasks are functions of the presentation layer? (Choose two.)

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

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Moderate

Concept notes: The presentation layer in the OSI model is responsible for data representation and encryption, among other tasks.

Common Mistakes: Students may confuse the presentation layer with the session layer, which handles session management and synchronization.

Explanations: The presentation layer is responsible for data compression and encryption. Compression reduces the size of data to speed up transmission, while encryption ensures data security by converting data into a secure format. Addressing is not a function of the presentation layer; it is handled by the network layer.

Option Analysis:

Option A: Compression is a function of the presentation layer.
Option B: Encryption is a function of the presentation layer.
Option C: Addressing is not a function of the presentation layer.
Option D: Only (A) & (B) are correct.

Mnemonic: PAC: Presentation, Addressing, Compression (Addressing is not in Presentation)

1956. In OSI model, which of the following layer transforms information from machine format into that understandable by user

Correct Answer: Correct answer is: (D) Presentation.

Exam Relevance: Networking Fundamentals, CCNA, CISSP

Difficulty: Moderate

Concept notes: The Presentation layer in the OSI model is responsible for transforming data into a format that is understandable by the application layer and ultimately the user.

Common Mistakes: Students often confuse the Presentation layer with the Application layer, as both deal with user interaction. However, the Presentation layer specifically handles data formatting and encryption, while the Application layer provides services directly to the user.

Explanations: The Presentation layer in the OSI model is tasked with transforming data into a format that is understandable by the application layer and ultimately the user. This layer is responsible for data encryption, compression, and formatting. It ensures that the data is presented in a way that the application layer can interpret and the user can understand. The other layers do not directly handle the transformation of data into a user-understandable format.

Option Analysis:

Option A: The Application layer provides services directly to the user but does not handle the transformation of data into a user-understandable format.
Option B: The Session layer manages sessions between applications but does not handle data transformation.
Option C: The Physical layer deals with the transmission of raw bit streams over a physical medium and does not handle data transformation.
Option D: The Presentation layer is responsible for transforming data into a format that is understandable by the application layer and ultimately the user.

Mnemonic: P for Presentation, P for Prepare (data for user).

1957. Signals with a frequency below 2 MHz use..... propagation.

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

Exam Relevance: GATE, ECE, Wireless Communication Exams

Difficulty: Easy

Concept notes: Signals with frequencies below 2 MHz typically propagate along the ground due to their longer wavelengths.

Common Mistakes: Students may confuse the propagation mode with higher frequency signals, which often use sky or line-of-sight propagation.

Explanations: Signals with frequencies below 2 MHz have longer wavelengths, which allow them to propagate along the ground. This type of propagation is known as ground wave propagation. Ground waves can travel over the Earth's surface, following the curvature of the Earth, making them suitable for long-distance communication at these frequencies.

Option Analysis:

Option A: Correct. Ground propagation is suitable for signals below 2 MHz.
Option B: Incorrect. Sky propagation is more common for higher frequency signals.
Option C: Incorrect. Line-of-sight propagation is used for very high frequency signals.
Option D: Incorrect. Ground propagation is the correct mode for these frequencies.

Mnemonic: Glowing Ground, Good for Low

1958. Which of the following routing algorithm takes into account the current network load.

Correct Answer: Correct answer is: (D) Distance vector routing.

Exam Relevance: CCNA, CompTIA Network+, CISSP

Difficulty: Moderate

Concept notes: Distance vector routing algorithms update their routing tables based on information received from neighboring routers, which includes the current network load.

Common Mistakes: Students may confuse distance vector routing with shortest path algorithms, which typically do not consider the current network load.

Explanations: Distance vector routing algorithms maintain and update routing tables based on information received from neighboring routers. This information includes the current network load, which allows the algorithm to dynamically adjust routes based on the current state of the network. In contrast, shortest path algorithms primarily focus on finding the shortest path between nodes without considering the current network load.

Option Analysis:

Option A: Broadcast routing does not take into account the current network load; it simply sends packets to all nodes in the network.
Option B: Shortest path algorithms focus on finding the shortest path between nodes and do not consider the current network load.
Option C: Flooding involves sending packets to all nodes in the network and does not take into account the current network load.
Option D: Distance vector routing updates its routing tables based on information from neighboring routers, which includes the current network load.

1959. In multicast communication, relationship is

Correct Answer: Correct answer is: (B) One to many.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Easy

Concept notes: Multicast communication is a method of sending data to multiple recipients simultaneously.

Common Mistakes: Students may confuse multicast with unicast (one-to-one) or broadcast (one-to-all).

Explanations: In multicast communication, a single sender transmits data to multiple receivers. This is different from unicast, where communication is one-to-one, and broadcast, where communication is one-to-all. Multicast is efficient for applications like video streaming or online gaming, where a single source needs to send data to multiple destinations.

Option Analysis:

Option A: Incorrect, as unicast is one-to-one communication.
Option B: Correct, as multicast is one-to-many communication.
Option C: Incorrect, as many-to-one communication is not a standard term in networking.
Option D: Incorrect, as many-to-many communication is not the defining characteristic of multicast.

1960. In transparent bridge, stations are completely unaware of existence of

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

Exam Relevance: CCNA, Network+, CompTIA Network+

Difficulty: Moderate

Concept notes: In a transparent bridge, the stations are unaware of the bridge's presence because the bridge operates at the data link layer and forwards frames based on MAC addresses without altering the frame's content.

Common Mistakes: Students may confuse the bridge with a repeater or switch, which also operate in network environments but have different functions and levels of visibility to the stations.

Explanations: A transparent bridge operates at the data link layer and forwards frames based on MAC addresses. It does not alter the frame's content, making it invisible to the stations. This transparency ensures that stations are unaware of the bridge's existence, as they communicate as if the bridge were not present. Repeaters and switches, while also part of network infrastructure, are not transparent in the same way.

Option Analysis:

Option A: Ports are physical or logical interfaces on a network device, and stations are aware of them as they connect to them.
Option B: Repeaters amplify signals and stations are aware of them as they are part of the physical layer and directly affect signal transmission.
Option C: Bridges operate at the data link layer and are transparent to stations, which are unaware of their presence.
Option D: Switches are aware of MAC addresses and manage traffic, but they are not transparent to stations as they can affect traffic flow and are part of the network infrastructure.

Mnemonic: Bridge = B, for "Bridging without being seen."

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Computer networking MCQ - Set 196

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