Computer networking MCQ – Change your future

181. Segmentation and Reassembly (SAR) sublayer of AAL 2 has only 1 field i.e.

Correct Answer: Correct answer is: (C) Start field.

Exam Relevance: Computer Networks, Telecommunications, ATM Networks

Difficulty: Easy

Concept notes: The Segmentation and Reassembly (SAR) sublayer of AAL 2 (ATM Adaptation Layer 2) is responsible for segmenting and reassembling data packets. It includes a single field known as the Start field, which indicates the beginning of a new packet.

Common Mistakes: Students may confuse the Start field with other fields such as the Synchronization field or Header Error Control field, which are not part of the SAR sublayer in AAL 2.

Explanations: The SAR sublayer in AAL 2 is designed to handle the segmentation and reassembly of data packets. It includes only one field, the Start field, which marks the beginning of a new packet. This field is crucial for identifying the start of a new data segment, ensuring proper reassembly at the receiving end.

Option Analysis:

Option A: The Synchronization field is not part of the SAR sublayer in AAL 2.
Option B: The Number protection field is not a recognized field in the SAR sublayer of AAL 2.
Option C: The Start field is the only field in the SAR sublayer of AAL 2, marking the beginning of a new packet.
Option D: The Header Error Control field is not part of the SAR sublayer in AAL 2.

Mnemonic: Start field signifies the start.

182. No retransmission timer is set for an

Correct Answer: Correct answer is: (B) ACK segment.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Moderate

Concept notes: In TCP/IP communication, an ACK segment is used to acknowledge receipt of data. No retransmission timer is set for an ACK segment because it is not a data-carrying segment and does not require retransmission if lost.

Common Mistakes: Students may confuse ACK segments with data segments, which do require retransmission timers.

Explanations: ACK segments are used to confirm the receipt of data segments. Since ACK segments do not carry data themselves, they do not need to be retransmitted if lost. Therefore, no retransmission timer is set for ACK segments. This is in contrast to data segments, which do require retransmission timers to ensure reliable data transmission.

Option Analysis:

Option A: RTO (Retransmission Timeout) is a timer used for data segments, not ACK segments.
Option B: ACK segment does not require a retransmission timer.
Option C: FIN segment is used to terminate a connection and does not require a retransmission timer.
Option D: Checksum segment is not a standard term in TCP/IP; checksums are used for error detection, not retransmission.

Mnemonic: ACK: Always Confirmed, No Retransmission

183. AMPS operates in the ISM..... band.

Correct Answer: Correct answer is: (A) 800-MHz.

Exam Relevance: GATE, GRE, Professional certification exams

Difficulty: Easy

Concept notes: AMPS (Advanced Mobile Phone System) operates in the ISM (Industrial, Scientific, and Medical) band at 800 MHz.

Common Mistakes: Students may confuse the frequency band with other mobile communication systems that operate in different bands.

Explanations: AMPS is a first-generation (1G) cellular technology that operates in the 800 MHz ISM band. This band is designated for unlicensed use, allowing AMPS to function without requiring a specific license for operation. The 800 MHz band is specifically allocated for mobile communication services, making it the correct choice for AMPS.

Option Analysis:

Option A: Correct. AMPS operates in the 800 MHz ISM band.
Option B: Incorrect. 900 MHz is not the correct band for AMPS.
Option C: Incorrect. 1800 MHz is not the correct band for AMPS.
Option D: Incorrect. The correct band is specified in the options.

Mnemonic: AMPS 800, Mobile's Home

184. Which uses a network access method based on detecting collisions between nodes?

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

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

Difficulty: Moderate

Concept notes: Ethernet uses a network access method based on detecting collisions between nodes.

Common Mistakes: Students may confuse Ethernet with Token Ring, which uses a token-passing method rather than collision detection.

Explanations: Ethernet employs Carrier Sense Multiple Access with Collision Detection (CSMA/CD). This method allows multiple devices to share the same communication channel. When a device wants to transmit data, it first listens to the network to check if the channel is free. If the channel is free, the device transmits the data. If two devices transmit simultaneously, a collision occurs, and both devices detect the collision. They then stop transmitting and wait for a random period before attempting to transmit again. This process ensures that the network can handle multiple devices efficiently while minimizing data loss due to collisions.

Option Analysis:

Option A: FDDI uses a token-passing method, not collision detection.
Option B: 802.11(Wi-Fi) uses CSMA/CA (Collision Avoidance), not collision detection.
Option C: Ethernet uses CSMA/CD, which involves detecting collisions.
Option D: Token ring uses a token-passing method, not collision detection.

185. In Frame Relay, the..... is the maximum number of bits in excess of Bc that a user can send during a predefined time.

Correct Answer: Correct answer is: (D) Excess burst size.

Exam Relevance: CCNA, CCNP, Network+

Difficulty: Moderate

Concept notes: In Frame Relay, the excess burst size (Be) is the maximum number of bits in excess of the committed burst size (Bc) that a user can send during a predefined time interval, known as the time interval (Tc).

Common Mistakes: Students often confuse the excess burst size with the committed burst size, thinking they are the same or similar concepts.

Explanations: The excess burst size (Be) in Frame Relay is defined as the maximum number of bits that can be sent in addition to the committed burst size (Bc) during a predefined time interval (Tc). This allows for occasional bursts of traffic beyond the committed rate without immediate penalty, providing flexibility in network traffic management.

Option Analysis:

Option A: Access rate is the maximum speed at which data can be transmitted over a network, not related to burst sizes.
Option B: Committed burst size (Bc) is the maximum amount of data that can be sent at the committed information rate (CIR) without incurring any Frame Relay Discard Eligibility (DE) marking.
Option C: Committed information rate (CIR) is the guaranteed data transfer rate that the network provider commits to deliver, not related to burst sizes.
Option D: Excess burst size (Be) is the correct term for the maximum number of bits in excess of Bc that can be sent during a predefined time interval.

Mnemonic: Excess Burst Size: "Extra Bits, Sometimes"

186. In IPv6, a.....address is used if a site with several networks uses the Internet protocols but is not connected to the Internet for security reasons.

Correct Answer: Correct answer is: (B) Site local.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Moderate

Concept notes: Site local addresses are used in IPv6 for communication within a local site or organization that is not connected to the Internet.

Common Mistakes: Students may confuse site local addresses with link local addresses, which are used for communication within a single link or network segment.

Explanations: Site local addresses are designed for use within a local site or organization that is not connected to the Internet. This makes them suitable for environments where internal communication is required but external connectivity is restricted for security reasons. Link local addresses, on the other hand, are used for communication within a single link or network segment, and mapped addresses are used to represent IPv4 addresses in an IPv6 environment.

Option Analysis:

Option A: Link local addresses are used for communication within a single link or network segment, not for an entire site.
Option B: Site local addresses are used for communication within a local site or organization that is not connected to the Internet, making them the correct choice.
Option C: Mapped addresses are used to represent IPv4 addresses in an IPv6 environment, not for internal site communication.
Option D: This option is incorrect as a valid address type is provided in option B.

187. The combination of..... and..... is often termed the local address of the local portion of the IP address.

Correct Answer: Correct answer is: (C) Subnet number and host number.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Moderate

Concept notes: In IP addressing, the local address refers to the portion of the IP address that is unique within a specific subnet.

Common Mistakes: Students often confuse the local address with the entire IP address, not recognizing the distinction between the network and local portions.

Explanations: The local address in an IP address is composed of the subnet number and the host number. The subnet number identifies a specific subnet within a larger network, while the host number uniquely identifies a device within that subnet. Together, they form the local address, which is used for communication within the subnet.

Option Analysis:

Option A: This option is incorrect because the network number and host number together form the entire IP address, not just the local address.
Option B: This option is incorrect because the network number and subnet number together form the network portion of the IP address, not the local address.
Option C: This option is correct because the combination of the subnet number and host number forms the local address within a subnet.
Option D: This option is incorrect because the host number alone does not form the local address; it must be combined with the subnet number.

Mnemonic: Subnet + Host = Local

188. Which of the following devices is a PC component that connects the computer to the network?

Correct Answer: Correct answer is: (B) NIC (Network Interface Card).

Exam Relevance: CCNA, CompTIA A+, Network+

Difficulty: Easy

Concept notes: A Network Interface Card (NIC) is a hardware component that allows a computer to connect to a network.

Common Mistakes: Students may confuse a NIC with other network devices like a bridge or gateway, which are not PC components.

Explanations: A NIC is a hardware component that connects a computer to a network. It is essential for enabling network communication and is a standard component in most computers. Other options like a bridge, DNS server, and gateway are network devices but not PC components.

Option Analysis:

Option A: A bridge is a network device that connects multiple network segments, not a PC component.
Option B: A NIC is a hardware component that connects a computer to a network, making it the correct answer.
Option C: A DNS server is a network service that translates domain names into IP addresses, not a PC component.
Option D: A gateway is a network device that routes traffic between different networks, not a PC component.

Mnemonic: NIC - Network Interface Card, Connects to Network

189. Which one of the following protocol delivers/stores mail to reciever server?

Correct Answer: Correct answer is: (A) Simple mail transfer protocol.

Exam Relevance: CISSP, CompTIA Network+, CCNA

Difficulty: Easy

Concept notes: The Simple Mail Transfer Protocol (SMTP) is responsible for delivering email from the sender's server to the receiver's server.

Common Mistakes: Students often confuse SMTP with POP3 or IMAP, which are used for retrieving emails from the server to the client, not for delivering emails between servers.

Explanations: SMTP is designed to transfer email messages from the sender's server to the receiver's server. It operates on the application layer of the TCP/IP model and uses port 25 for communication. The protocol ensures that the email is delivered to the correct destination server, where it can then be accessed by the recipient.

Option Analysis:

Option A: Correct. SMTP is used for delivering email to the receiver's server.
Option B: Incorrect. Post Office Protocol (POP) is used for retrieving emails from the server to the client.
Option C: Incorrect. Internet Message Access Protocol (IMAP) is also used for retrieving emails from the server to the client.
Option D: Incorrect. Hypertext Transfer Protocol (HTTP) is used for transferring web pages and other data over the internet, not for email delivery.

Mnemonic: SMTP: Send Mail To People

190. Unlike TCP, this alternative method of data exchange does not provide the service of dividing a message into packets and reassembling it at the other end, but instead relies on the application program to make sure that the entire message has arrived and is in the right order.

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

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Moderate

Concept notes: UDP (User Datagram Protocol) is a connectionless protocol that does not provide the service of dividing messages into packets and reassembling them at the destination. Instead, it relies on the application layer to handle these tasks.

Common Mistakes: Students often confuse UDP with TCP, which does provide packet segmentation and reassembly.

Explanations: UDP does not provide the service of dividing messages into packets and reassembling them at the destination. This is a key feature that distinguishes UDP from TCP. In UDP, the application program must ensure that the entire message has arrived and is in the correct order. This makes UDP suitable for applications where speed is more important than reliability, such as real-time video streaming or online gaming.

Option Analysis:

Option A: SMTP (Simple Mail Transfer Protocol) is used for sending and receiving email messages and is not related to the packet segmentation and reassembly process described in the question.
Option B: UDP (User Datagram Protocol) is the correct answer as it does not provide the service of dividing messages into packets and reassembling them at the destination.
Option C: DHCP (Dynamic Host Configuration Protocol) is used for assigning IP addresses and other network configuration parameters to devices on a network and is not related to the packet segmentation and reassembly process described in the question.
Option D: None of the above is incorrect because UDP is the correct answer.

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Computer networking MCQ - Set 19

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