Computer networking MCQ – Change your future

761. What is the frequency range of 802.11g standard?

Correct Answer: Correct answer is: (A) 2.4 GHz.

Exam Relevance: IEEE certification exams, Computer Networks exams, Wireless Communication exams

Difficulty: Easy

Concept notes: The 802.11g standard operates in the 2.4 GHz frequency band.

Common Mistakes: Students may confuse the 802.11g standard with the 802.11a standard, which operates in the 5.0 GHz band.

Explanations: The 802.11g standard is part of the IEEE 802.11 family of standards for wireless local area networks (WLANs). It operates in the 2.4 GHz frequency band, which is the same as the 802.11b standard. This frequency band is widely used for wireless communication due to its ability to penetrate walls and other obstacles effectively.

Option Analysis:

Option A: Correct. The 802.11g standard operates in the 2.4 GHz frequency band.
Option B: Incorrect. The 5.0 GHz frequency band is used by the 802.11a and 802.11n (in some cases) standards, not 802.11g.
Option C: Incorrect. The 3.0 GHz frequency band is not used by the 802.11g standard.
Option D: Incorrect. The correct frequency band is specified in the options.

Mnemonic: 2.4 GHz for g, think "g for good 2.4 GHz."

762. In Bluetooth, the..... layer is roughly equivalent to the physical layer of the Internet model.

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

Exam Relevance: Computer Networks, Wireless Communication, Network Protocols

Difficulty: Easy

Concept notes: In Bluetooth, the Radio layer is responsible for the physical transmission and reception of data over the air, which is equivalent to the physical layer in the Internet model.

Common Mistakes: Students may confuse the Radio layer with the Baseband layer, which handles the link control and link management functions.

Explanations: The Radio layer in Bluetooth is responsible for the physical transmission and reception of data over the air. This layer deals with the modulation and demodulation of signals, as well as the physical characteristics of the radio frequency (RF) communication. This is analogous to the physical layer in the Internet model, which is also responsible for the physical transmission of data over a medium. Therefore, the Radio layer in Bluetooth is equivalent to the physical layer in the Internet model.

Option Analysis:

Option A: Correct. The Radio layer in Bluetooth is equivalent to the physical layer in the Internet model.
Option B: Incorrect. The Baseband layer in Bluetooth handles link control and link management, not the physical transmission of data.
Option C: Incorrect. L2CAP (Logical Link Control and Adaptation Protocol) is a higher layer that manages the data flow between different protocols and applications, not the physical transmission.
Option D: Incorrect. The correct answer is provided in the options.

Mnemonic: Radio = Physical

763. Connecting device that is used to connect wires coming from different branches is known as

Correct Answer: Correct answer is: (D) Passive hubs.

Exam Relevance: Networking Fundamentals, CCNA, CompTIA Network+

Difficulty: Easy

Concept notes: A passive hub is a device that connects multiple network segments together and allows data to pass through it without any processing.

Common Mistakes: Students may confuse passive hubs with active hubs, which amplify and regenerate signals, or with bridges, which operate at the data link layer and filter traffic.

Explanations: Passive hubs are used to connect wires coming from different branches in a network. They do not process or amplify the signals; they simply pass the data through to all connected devices. This makes them suitable for connecting multiple network segments without the need for active processing.

Option Analysis:

Option A: Bridges operate at the data link layer and filter traffic, not simply connect wires.
Option B: Active hubs amplify and regenerate signals, which is not the function of a device that simply connects wires.
Option C: Repeaters amplify signals, but do not connect multiple branches in the same way a hub does.
Option D: Passive hubs connect wires from different branches without processing the data.

764. In byte stuffing, a special byte is added to data section of frame when there is a character with same pattern as the

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

Exam Relevance: Computer Networks, Data Communication, Network Protocols

Difficulty: Moderate

Concept notes: In byte stuffing, a special byte is added to the data section of a frame to avoid confusion with the flag byte that marks the beginning and end of a frame.

Common Mistakes: Students often confuse byte stuffing with error detection or correction techniques, which are different mechanisms.

Explanations: Byte stuffing is a technique used in data communication to ensure that the data section of a frame does not contain a sequence that could be mistaken for the flag byte. The flag byte is used to delineate the start and end of a frame. If the data section contains a byte that matches the flag byte, a special byte (often called an escape byte) is inserted before the matching byte to prevent the receiver from incorrectly interpreting the data as a frame boundary. This ensures that the frame structure is maintained and the data is transmitted accurately.

Option Analysis:

Option A: Correct. Byte stuffing is used to avoid confusion with the flag byte.
Option B: Incorrect. Byte stuffing is not related to error detection or correction.
Option C: Incorrect. Byte stuffing is not related to the sender's identity.
Option D: Incorrect. Byte stuffing is not related to the destination's identity.

765. Masks in slash notation of 255.255.255.0 would be

Correct Answer: Correct answer is: (B) /24.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Easy

Concept notes: The mask in slash notation represents the number of bits set to 1 in the subnet mask.

Common Mistakes: Students often confuse the number of bits set to 1 with the number of bits set to 0.

Explanations: The subnet mask 255.255.255.0 in binary is 11111111.11111111.11111111.00000000. This shows 24 bits set to 1, which corresponds to /24 in slash notation.

Option Analysis:

Option A: Incorrect, as /8 represents 8 bits set to 1, which is 255.0.0.0.
Option B: Correct, as /24 represents 24 bits set to 1, which is 255.255.255.0.
Option C: Incorrect, as /32 represents 32 bits set to 1, which is 255.255.255.255.
Option D: Incorrect, as /36 is not a valid subnet mask in IPv4, which has a maximum of 32 bits.

766. In IEEE 802.11, the MAC layer frame has..... fields.

Correct Answer: Correct answer is: (D) None of the above.

Exam Relevance: Computer Networks, Wireless Communications, IEEE 802.11

Difficulty: Moderate

Concept notes: The IEEE 802.11 MAC layer frame structure includes more than six fields, making the options A, B, and C incorrect.

Common Mistakes: Students may incorrectly count only the most prominent fields, such as the header, payload, and footer, without considering all the fields specified in the IEEE 802.11 standard.

Explanations: The IEEE 802.11 MAC layer frame includes fields such as the Frame Control, Duration, Address fields (Address 1 to Address 4), Sequence Control, and the Frame Body. Additionally, there are fields for the Frame Check Sequence (FCS) and other optional fields like the Quality of Service (QoS) Control field. Therefore, the correct answer is "None of the above" as the number of fields exceeds six.

Option Analysis:

Option A: Incorrect, as the number of fields is more than four.
Option B: Incorrect, as the number of fields is more than five.
Option C: Incorrect, as the number of fields is more than six.
Option D: Correct, as the number of fields in the IEEE 802.11 MAC layer frame exceeds six.

767. Sending an e-mail requires

Correct Answer: Correct answer is: (C) Connection-oriented approach with no timing relationship between sender and receiver.

Exam Relevance: Computer Networks, Data Communication, Network Security

Difficulty: Moderate

Concept notes: E-mail transmission involves a connection-oriented approach where the sender and receiver establish a connection before data transfer. However, the timing relationship between the sender and receiver is not strictly required, as e-mails can be sent and received asynchronously.

Common Mistakes: Students may mistakenly believe that e-mail requires a real-time connection and timing relationship, similar to a phone call.

Explanations: E-mail systems use a connection-oriented approach, meaning a connection is established between the sender's and receiver's mail servers before the e-mail is sent. However, once the e-mail is sent, the sender does not need to wait for the receiver to be online to receive the message. The e-mail can be stored on the receiver's server until the receiver checks their inbox. This asynchronous nature means there is no strict timing relationship between the sender and receiver.

Option Analysis:

Option A: Incorrect because e-mail does not require a timing relationship between the sender and receiver.
Option B: Incorrect because e-mail uses a connection-oriented approach, not a connection-less approach.
Option C: Correct because e-mail uses a connection-oriented approach with no strict timing relationship.
Option D: Incorrect because e-mail uses a connection-oriented approach, not a connection-less approach.

768. Which of the following layer decide the transmission rate in a Network?

Correct Answer: Correct answer is: (A) Physical layer.

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

Difficulty: Easy

Concept notes: The physical layer is responsible for the transmission of raw bit streams over a physical medium and includes the specification of transmission rates.

Common Mistakes: Students often confuse the physical layer with the data link layer, which is responsible for error detection and correction, not transmission rates.

Explanations: The physical layer is the lowest layer in the OSI model and is responsible for the physical transmission of data. It defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link between end systems. Transmission rates, such as the speed at which data is sent over a network, are determined at this layer.

Option Analysis:

Option A: Correct. The physical layer is responsible for transmission rates.
Option B: Incorrect. The data link layer is responsible for error detection and correction, not transmission rates.
Option C: Incorrect. The network layer is responsible for routing and logical addressing, not transmission rates.
Option D: Incorrect. The transport layer is responsible for end-to-end communication and flow control, not transmission rates.

769. Which standard TCP port is assigned for contacting SSH servers?

Correct Answer: Correct answer is: (B) Port 22.

Exam Relevance: CISSP, CompTIA Security+, CCNA

Difficulty: Easy

Concept notes: SSH (Secure Shell) is a cryptographic network protocol for operating network services securely over an unsecured network. It is commonly used for remote command-line login and remote command execution.

Common Mistakes: Students often confuse the port numbers for different services, such as FTP (Port 21) and Telnet (Port 23), with SSH (Port 22).

Explanations: SSH uses port 22 by default to establish secure connections. This is a standard configuration recognized by network administrators and security professionals.

Option Analysis:

Option A: Port 21 is used for FTP (File Transfer Protocol), not SSH.
Option B: Port 22 is the correct port for SSH.
Option C: Port 23 is used for Telnet, not SSH.
Option D: Port 24 is not a standard port for SSH or any other common network service.

Mnemonic: SSH = Secure Shell = 22

770. Bluetooth technology was originally started as a project by the

Correct Answer: Correct answer is: (C) Ericsson Company.

Exam Relevance: General Knowledge Exams, Technology History Exams

Difficulty: Easy

Concept notes: Bluetooth technology was initiated as a project by the Ericsson Company in the early 1990s.

Common Mistakes: Students may mistakenly believe that Bluetooth was developed by a more well-known consumer electronics company like Apple or Samsung.

Explanations: Bluetooth technology was originally conceived by the Swedish telecommunications company Ericsson in 1994. The project aimed to create a wireless technology for short-range communication between devices. This initiative was later developed into the Bluetooth standard we use today.

Option Analysis:

Option A: Apple Company did not initiate Bluetooth technology.
Option B: Dell Company is not associated with the inception of Bluetooth technology.
Option C: Ericsson Company is the correct answer as it initiated the Bluetooth project.
Option D: Samsung Company did not start the Bluetooth technology project.

Mnemonic: E for Ericsson, E for Early Bluetooth

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Computer networking MCQ - Set 77

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