Computer networking MCQ – Change your future

121. This is a set of instructions for Web pages given through the browser

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

Exam Relevance: AP Computer Science Principles, SAT Subject Test in Computer Science

Difficulty: Easy

Concept notes: A script is a set of instructions that can be executed by a web browser to perform various tasks on a webpage.

Common Mistakes: Students may confuse a script with a URL, which is simply a web address, or with DNS, which translates domain names into IP addresses.

Explanations: A script is a set of instructions that can be executed by a web browser to perform various tasks on a webpage. This aligns with the description of a set of instructions given through the browser. URLs, DNS, and IP addresses do not fit this description as they are not sets of executable instructions.

Option Analysis:

Option A: URL is a web address, not a set of instructions.
Option B: DNS translates domain names to IP addresses, not a set of instructions.
Option C: Script is a set of instructions executed by a browser.
Option D: IP address is a numerical label for a device on a network, not a set of instructions.

122. The..... field determines the lifetime of IPv6 datagram

Correct Answer: Correct answer is: (A) Hop limit.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Easy

Concept notes: The Hop Limit field in the IPv6 header determines the maximum number of hops (routers) a packet can traverse before being discarded.

Common Mistakes: Students often confuse the Hop Limit field with the TTL (Time to Live) field from IPv4, which serves a similar purpose.

Explanations: In IPv6, the Hop Limit field is analogous to the TTL field in IPv4. It specifies the maximum number of hops a packet can traverse before being discarded. Each router that forwards the packet decrements the Hop Limit by one. If the Hop Limit reaches zero, the packet is discarded and an ICMPv6 Time Exceeded message is sent back to the source.

Option Analysis:

Option A: Correct. The Hop Limit field determines the lifetime of an IPv6 datagram in terms of the number of hops it can traverse.
Option B: Incorrect. TTL is a field in IPv4, not IPv6.
Option C: Incorrect. The Next Header field specifies the type of extension header or the payload following the IPv6 header.
Option D: Incorrect. The correct field is specified in Option A.

123. In IEEE 802.11, the addressing mechanism can include up to.....addresses.

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

Exam Relevance: Computer Networks, Wireless Communication, IEEE Standards

Difficulty: Easy

Concept notes: In IEEE 802.11, the addressing mechanism can include up to four addresses in a frame.

Common Mistakes: Students may confuse the number of addresses with the number of fields in the frame header.

Explanations: IEEE 802.11 frames can include up to four addresses: the source address (SA), the destination address (DA), the transmitter address (TA), and the receiver address (RA). This addressing scheme allows for complex communication scenarios, including point-to-point, broadcast, and multicast transmissions.

Option Analysis:

Option A: Correct. IEEE 802.11 frames can include up to four addresses.
Option B: Incorrect. IEEE 802.11 frames do not include five addresses.
Option C: Incorrect. IEEE 802.11 frames do not include six addresses.
Option D: Incorrect. The correct number of addresses is specified in the IEEE 802.11 standard.

124. The port number is "ephemeral port number", if the source host is.....

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

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Moderate

Concept notes: Ephemeral port numbers are temporary port numbers used by clients to communicate with servers.

Common Mistakes: Students may confuse ephemeral ports with well-known ports used by servers.

Explanations: Ephemeral ports are used by clients to establish temporary connections to servers. These ports are dynamically assigned by the operating system and are typically in the range of 49152 to 65535. When a client initiates a connection to a server, it uses an ephemeral port as the source port. This ensures that each connection is uniquely identified and can be managed by the operating system. Servers, on the other hand, use well-known or registered ports for their services, which are static and predefined.

Option Analysis:

Option A: NTP (Network Time Protocol) uses a well-known port (123) and is not related to ephemeral ports.
Option B: Echo uses a well-known port (7) and is not related to ephemeral ports.
Option C: Servers use well-known or registered ports, not ephemeral ports.
Option D: Clients use ephemeral ports for temporary connections to servers.

Mnemonic: Ephemeral = Ephemeral, Ephemeral, Ephemeral (E3) - Client's temporary port.

125. Which of the following could not be an Ethernet unicast destination?

Correct Answer: Correct answer is: (A) 43:7B:6C:DE:10:00.

Exam Relevance: CCNA, CompTIA Network+, CISSP

Difficulty: Moderate

Concept notes: In Ethernet, the first bit of the first byte in a MAC address indicates whether the address is unicast or multicast. A unicast address has the first bit set to 0, while a multicast address has the first bit set to 1.

Common Mistakes: Students often overlook the significance of the first bit in the MAC address and may not recognize the difference between unicast and multicast addresses.

Explanations: The correct answer is 43:7B:6C:DE:10:00 because the first bit of the first byte (43 in hexadecimal) is set to 1, indicating a multicast address. In binary, 43 is 01000011, where the first bit is 1. Therefore, this address cannot be a unicast destination.

Option Analysis:

Option A: 43:7B:6C:DE:10:00 - The first bit of the first byte is 1, indicating a multicast address.
Option B: 44:AA:C1:23:45:32 - The first bit of the first byte is 0, indicating a unicast address.
Option C: 46:56:21:1A:DE:F4 - The first bit of the first byte is 0, indicating a unicast address.
Option D: 48:32:21:21:4D:34 - The first bit of the first byte is 0, indicating a unicast address.

126. Which type of network needs to use the phones lines and cables from other companies? (leased lines)

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

Exam Relevance: CCNA, CompTIA Network+, CISSP

Difficulty: Moderate

Concept notes: Wide Area Networks (WANs) often require leased lines and cables from other companies to connect geographically dispersed locations.

Common Mistakes: Students may confuse LANs with WANs, thinking that both require leased lines from other companies.

Explanations: WANs are designed to connect devices over large geographical areas, often spanning cities, countries, or even continents. To achieve this, WANs frequently rely on leased lines and cables provided by telecommunications companies. These leased lines ensure reliable and secure communication between distant locations. In contrast, LANs typically operate within a single building or a small area and do not require leased lines from other companies.

Option Analysis:

Option A: LANs operate within a limited area and do not require leased lines from other companies.
Option B: WANs often need leased lines and cables from other companies to connect geographically dispersed locations.
Option C: This option is incorrect because only WANs need leased lines.
Option D: This option is incorrect because WANs do require leased lines.

Mnemonic: WANs Wide Area Networks, Wide World, Leased Lines

127. A transmission medium in which one station is transmitter and the other station is receiver, is termed as

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

Exam Relevance: Networking exams, Computer Science exams, Telecommunications exams

Difficulty: Easy

Concept notes: In simplex communication, data can only be transmitted in one direction.

Common Mistakes: Students may confuse simplex with half-duplex, where communication can occur in both directions but not simultaneously.

Explanations: Simplex communication is characterized by a unidirectional data flow. In this mode, one station acts as the transmitter and the other as the receiver. There is no simultaneous two-way communication, which distinguishes it from half-duplex and full-duplex modes.

Option Analysis:

Option A: Simplex is the correct term for one-way communication.
Option B: Half-duplex allows for two-way communication but not simultaneously.
Option C: Full duplex allows for simultaneous two-way communication.
Option D: None of the above is incorrect as simplex is a valid communication mode.

Mnemonic: S - Simplex, Single direction

128. These are key elements of protocol, except

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

Exam Relevance: Networking exams, Computer Science exams, IT certifications

Difficulty: Moderate

Concept notes: The key elements of a protocol include syntax, timing, and semantics. Data is not considered a key element of a protocol.

Common Mistakes: Students may mistakenly believe that data is a fundamental component of a protocol, confusing it with the content that protocols manage.

Explanations: A protocol defines the rules for communication between systems. The key elements are syntax (the format of the data), timing (when data is sent and received), and semantics (the meaning of the data). Data itself is not a component of the protocol but rather the content that the protocol manages.

Option Analysis:

Option A: Syntax is a key element of a protocol, defining the format of the data.
Option B: Data is not a key element of a protocol but the content that the protocol manages.
Option C: Timing is a key element of a protocol, defining when data is sent and received.
Option D: Semantics is a key element of a protocol, defining the meaning of the data.

129. Which of the following describe the DHCP Discover message? 1. It uses FF:FF:FF:FF:FF:FF as a layer 2 broadcast. 2. It uses UDP as the Transport layer protocol. 3. It uses TCP as the Transport layer protocol. 4. It does not use a layer 2 destination address.

Correct Answer: Correct answer is: (B) 1 and 2.

Exam Relevance: CCNA, CISSP, CompTIA Network+

Difficulty: Easy

Concept notes: The DHCP Discover message is a broadcast message used by a client to locate a DHCP server on the network.

Common Mistakes: Students may confuse the transport layer protocol used by DHCP messages, thinking TCP is used instead of UDP.

Explanations: The DHCP Discover message is sent as a broadcast, using FF:FF:FF:FF:FF:FF as the layer 2 destination address. It uses UDP as the transport layer protocol, not TCP. Therefore, statements 1 and 2 are correct.

Option Analysis:

Option A: Incorrect because it omits the correct statement about the transport layer protocol (UDP).
Option B: Correct because it includes both correct statements about the broadcast address and the transport layer protocol.
Option C: Incorrect because it includes the wrong transport layer protocol (TCP) and an incorrect statement about the layer 2 destination address.
Option D: Incorrect because it only includes an incorrect statement about the layer 2 destination address.

130. In periodic update, a node sends its routing table normally after every

Correct Answer: Correct answer is: (C) 30s.

Exam Relevance: CCNA, CISSP, Network+

Difficulty: Easy

Concept notes: In periodic updates, nodes in a network periodically broadcast their routing tables to their neighbors to ensure that the network topology information is up-to-date.

Common Mistakes: Students may confuse the periodic update interval with other network timing parameters, such as the interval for link-state updates or the timeout period for route entries.

Explanations: The correct answer is 30 seconds because in periodic updates, nodes typically send their routing tables every 30 seconds to maintain network topology information. This interval is a standard configuration in many routing protocols to ensure that the routing information remains current without overwhelming the network with frequent updates.

Option Analysis:

Option A: 10 seconds is too short for periodic updates, as it would cause excessive network traffic.
Option B: 20 seconds is shorter than the standard interval for periodic updates.
Option C: 30 seconds is the correct interval for periodic updates, ensuring that the routing information is updated frequently enough without causing network congestion.
Option D: 40 seconds is longer than the standard interval for periodic updates, which could lead to outdated routing information.

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Computer networking MCQ - Set 13

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