Computer networking MCQ – Change your future

841. For multicasting between two noncontiguous multicast routers, we make a multicast

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

Exam Relevance: CCNA, CCNP, Network+

Difficulty: Moderate

Concept notes: In a network, a backbone is a high-speed data channel that connects multiple networks or subnetworks. For multicasting between noncontiguous multicast routers, a backbone network is used to ensure that multicast traffic can be efficiently routed across different segments of the network.

Common Mistakes: Students may mistakenly think that a port, frame network, or switch is sufficient for multicasting between noncontiguous routers, overlooking the need for a backbone to connect different network segments.

Explanations: A backbone network is essential for multicasting between noncontiguous multicast routers because it provides the necessary infrastructure to route multicast traffic across different network segments. Without a backbone, multicast traffic would be limited to the local network segment and unable to reach routers in other segments.

Option Analysis:

Option A: A port is a logical construct used for communication between devices and is not sufficient for connecting noncontiguous multicast routers.
Option B: A frame network is a type of network topology and does not provide the necessary connectivity for multicasting between noncontiguous routers.
Option C: A switch is a device that connects devices within a local network but does not provide the necessary connectivity for multicasting between noncontiguous routers.
Option D: A backbone network is the correct choice as it provides the necessary infrastructure to route multicast traffic across different network segments.

Mnemonic: Backbone: Big, Broad, Backbone

842. When a user wants to access an application program or utility located on a remote machine, he or she performs..... login.

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

Exam Relevance: CISSP, CompTIA Network+, CCNA

Difficulty: Easy

Concept notes: A remote login allows a user to access applications and utilities on a remote machine over a network.

Common Mistakes: Students may confuse remote login with local login, which is used to access resources on the same machine.

Explanations: When a user wants to access an application program or utility located on a remote machine, a remote login is performed. This type of login enables the user to connect to the remote machine and use its resources as if they were local. The correct answer is remote login because it specifically refers to accessing resources on a different machine over a network.

Option Analysis:

Option A: Local login is incorrect because it refers to accessing resources on the same machine.
Option B: Remote login is the correct answer as it involves accessing resources on a different machine over a network.
Option C: Temporary login is not a standard term in this context and does not accurately describe the process of accessing remote resources.
Option D: None of the above is incorrect because remote login is a valid and standard term.

Mnemonic: Remote = Reach Out

843. RPF eliminates the..... in the flooding process.

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

Exam Relevance: CCNA, CCNP, Network+

Difficulty: Moderate

Concept notes: RPF (Reverse Path Forwarding) is a mechanism used in multicast routing to prevent loops and redundant packet transmissions. It ensures that packets are forwarded only in the direction of the source, thereby eliminating unnecessary flooding.

Common Mistakes: Students often misunderstand RPF as a method that eliminates the entire flooding process, when in fact it only eliminates redundant or unnecessary flooding.

Explanations: RPF does not eliminate the flooding process itself but rather ensures that packets are forwarded only in the direction of the source, preventing loops and redundant transmissions. This mechanism is crucial for efficient multicast routing, ensuring that packets are not unnecessarily duplicated and forwarded in all directions.

Option Analysis:

Option A: Forwarding is not eliminated by RPF; it is controlled to prevent loops.
Option B: Backwarding is not a term used in the context of RPF.
Option C: RPF does not eliminate flooding entirely; it eliminates redundant or unnecessary flooding.
Option D: None of the above is correct because RPF does not eliminate any of the listed options but rather controls the forwarding process to prevent redundant transmissions.

Mnemonic: RPF: Reverse Path Forwarding, not Reverse Path Flooding.

844. Four routers have to be interconnected in a point-to-point Network. Each pair of root us may connected by a high-speed line, a medium speed line or a low speed line. Find the total number of topologies.

Correct Answer: Correct answer is: (D) 729.

Exam Relevance: Computer Networks, Discrete Mathematics, Combinatorics

Difficulty: Hard

Concept notes: The problem involves calculating the number of possible topologies for a network of four routers, where each pair of routers can be connected by one of three types of lines (high-speed, medium-speed, or low-speed).

Common Mistakes: Students may incorrectly assume that the number of topologies is simply the number of ways to choose the type of line for each pair, without considering the combinatorial nature of the problem.

Explanations: To find the total number of topologies, we need to consider all possible connections between the four routers. There are 6 unique pairs of routers (since the number of ways to choose 2 out of 4 is given by the combination formula \( \binom{4}{2} = 6 \)). Each pair can be connected by one of three types of lines. Therefore, the total number of topologies is calculated by raising the number of line types to the power of the number of pairs, which is \( 3^6 = 729 \).

Option Analysis:

Option A: 12 is incorrect because it does not account for the combinatorial nature of the problem and the number of line types.
Option B: 81 is incorrect because it only considers a subset of the possible connections, not all 6 pairs.
Option C: 48 is incorrect because it does not correctly apply the combinatorial formula for the number of topologies.
Option D: 729 is correct because it correctly calculates the total number of topologies by considering all 6 pairs and the 3 types of lines for each pair.

845. In standard Ethernet, data is converted to a digital signal using the

Correct Answer: Correct answer is: (D) Manchester Scheme.

Exam Relevance: Computer Networks, Data Communications, Network Fundamentals

Difficulty: Moderate

Concept notes: In standard Ethernet, data is converted to a digital signal using the Manchester Scheme, which ensures a transition at the middle of each bit period, providing a self-clocking signal.

Common Mistakes: Students often confuse Manchester encoding with other line coding schemes like NRZ (Non-Return-to-Zero) schemes, which do not provide the same self-clocking feature.

Explanations: Manchester encoding is used in standard Ethernet because it provides a self-clocking signal, ensuring that the receiver can accurately synchronize with the sender. This is achieved by having a transition at the middle of each bit period, which helps in maintaining the clock synchronization without the need for a separate clock signal.

Option Analysis:

Option A: NRZ Scheme does not provide self-clocking and is not used in standard Ethernet.
Option B: NRZ-L (Non-Return-to-Zero Level) is a variation of NRZ but does not provide self-clocking and is not used in standard Ethernet.
Option C: NRZ-I (Non-Return-to-Zero Inverted) is another variation of NRZ but also does not provide self-clocking and is not used in standard Ethernet.
Option D: Manchester Scheme is the correct choice as it is used in standard Ethernet for its self-clocking feature.

Mnemonic: Mnemonic: "Manchester Makes Mid-Bit Moves"

846. The IP packet that carries an IGMP packet has a value of..... in its protocol field.

Correct Answer: Correct answer is: (B) 2.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Easy

Concept notes: The protocol field in an IP packet identifies the protocol used in the data portion of the packet. For IGMP (Internet Group Management Protocol), the protocol field value is 2.

Common Mistakes: Students may confuse the protocol field value for IGMP with other protocols, such as ICMP (Internet Control Message Protocol), which has a value of 1.

Explanations: The protocol field in an IP packet is used to identify the protocol of the data carried in the packet. For IGMP, the protocol field value is 2. This is a standard value defined in the IP protocol specifications.

Option Analysis:

Option A: Incorrect, as the value 3 is not associated with IGMP.
Option B: Correct, as the value 2 is the standard protocol field value for IGMP.
Option C: Incorrect, as the value 1 is associated with ICMP, not IGMP.
Option D: Incorrect, as the value 2 is the correct protocol field value for IGMP.

847. What is the loopback address?

Correct Answer: Correct answer is: (A) 127.0.0.1.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Very Easy

Concept notes: The loopback address is a special IP address used to send packets to the same machine.

Common Mistakes: Students may confuse the loopback address with broadcast addresses or other special IP addresses.

Explanations: The loopback address, 127.0.0.1, is used to test the IP stack on a local machine. It is a reserved address that always refers to the local machine itself, allowing network software to be tested without requiring a physical network connection.

Option Analysis:

Option A: 127.0.0.1 is the correct loopback address.
Option B: 255.0.0.0 is a class A broadcast address, not a loopback address.
Option C: 255.255.0.0 is a class B broadcast address, not a loopback address.
Option D: 255.255.255.255.0 is not a valid IP address format and is not a loopback address.

Mnemonic: Loopback, Localhost, 127.0.0.1

848. Device that splits a network connection into multiple computers

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

Exam Relevance: CCNA, Network+ Certification

Difficulty: Easy

Concept notes: A hub is a networking device that connects multiple devices on a network and allows them to communicate with each other.

Common Mistakes: Students may confuse a hub with a switch or router, which also connect devices but operate differently.

Explanations: A hub is a simple device that broadcasts incoming data to all connected devices. It does not analyze or manage the data flow, making it less sophisticated than a switch or router. However, it effectively splits a network connection to allow multiple computers to connect to the network.

Option Analysis:

Option A: A hub is the correct answer as it splits a network connection into multiple computers by broadcasting data to all connected devices.
Option B: A switch is more advanced than a hub and selectively forwards data to the appropriate device, rather than broadcasting to all devices.
Option C: A router is used to connect multiple networks and route data between them, not to split a single network connection.
Option D: A server is a computer that provides services to other computers on a network, but it does not split a network connection.

Mnemonic: Hub = Hub and Spoke, connecting all.

849. Used for Internet service providers or other types of networks

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

Exam Relevance: CISSP, CompTIA Network+, CCNA

Difficulty: Easy

Concept notes: The .net domain is commonly used by Internet service providers and other types of networks.

Common Mistakes: Students may confuse .net with .com, thinking .com is also used for Internet service providers.

Explanations: The .net domain is specifically designed for use by Internet service providers and other network-related organizations. It is intended to distinguish these entities from commercial businesses, which typically use the .com domain. Therefore, .net is the appropriate choice for Internet service providers and other network-related services.

Option Analysis:

Option A: .com is primarily used for commercial businesses, not specifically for Internet service providers or network-related organizations.
Option B: .net is the correct choice for Internet service providers and other network-related organizations.
Option C: .org is typically used for non-profit organizations, not specifically for Internet service providers or network-related organizations.
Option D: .edu is reserved for educational institutions, not for Internet service providers or network-related organizations.

850. Range of port numbers in Internet model is

Correct Answer: Correct answer is: (D) 0 and 65, 535(16-bit).

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Easy

Concept notes: In the Internet model, port numbers are used to identify specific processes or services on a host. These port numbers are 16-bit values, ranging from 0 to 65,535.

Common Mistakes: Students may confuse the range of port numbers with the range of IP addresses or other numerical ranges in networking.

Explanations: Port numbers in the Internet model are 16-bit values, which means they can range from 0 to 65,535. This range is defined by the size of the 16-bit field used to represent port numbers in network protocols.

Option Analysis:

Option A: Incorrect because the range is not 0 to 32,765 and the bit size is not 8-bit.
Option B: Incorrect because the range is not 0 to 32,765 and the bit size is not 16-bit.
Option C: Incorrect because the bit size is not 32-bit.
Option D: Correct because the range is 0 to 65,535 and the bit size is 16-bit.

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Computer networking MCQ - Set 85

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