Computer Networks MCQ Questions And Answers

Computer Networks MCQ Questions And Answers

51. What is the full form of LAN and what is its coverage area?

  1. Large Area Network — covers an entire country
  2. Local Area Network — covers a small geographic area like a building or campus
  3. Linked Access Network — links multiple cities
  4. Low Access Network — covers underground networks

Answer : B
Explanation: LAN (Local Area Network) connects devices within a small geographic area such as a home, office, or campus building. It offers high data transfer speeds and low latency. WAN (Wide Area Network) covers large geographic areas like countries, while MAN (Metropolitan Area Network) covers a city or large campus.

52. What is the difference between LAN, MAN, and WAN?

  1. LAN is the largest; WAN is the smallest
  2. LAN covers a small area; MAN covers a city; WAN covers countries or continents
  3. MAN is wireless only; LAN and WAN are wired only
  4. WAN is faster than LAN in all cases

Answer : B
Explanation: LAN (Local Area Network) covers a small area like a single building. MAN (Metropolitan Area Network) spans a city or large campus — examples include cable TV networks. WAN (Wide Area Network) covers large geographic areas such as countries or continents — the internet itself is the largest WAN. Speed generally decreases and cost increases as the network size grows.

53. What is a MAC address in computer networking?

  1. A logical address assigned by the network administrator
  2. A unique physical address assigned to a network interface card by the manufacturer
  3. An address used only for wireless devices
  4. A temporary address assigned by DHCP

Answer : B
Explanation: A MAC (Media Access Control) address is a unique 48-bit hardware identifier permanently assigned to a network interface card (NIC) by its manufacturer. It is written as six pairs of hexadecimal digits (e.g., 00:1A:2B:3C:4D:5E). While IP addresses can change, MAC addresses are fixed and used for device identification within a local network at Layer 2.

54. What is subnetting and why is it used?

  1. Subnetting is used to combine multiple networks into one large network
  2. Subnetting divides a large network into smaller sub-networks to improve performance and security
  3. Subnetting is used to increase the speed of data transmission
  4. Subnetting assigns MAC addresses to network devices

Answer : B
Explanation: Subnetting is the process of dividing a large IP network into smaller, more manageable sub-networks (subnets). It improves network performance by reducing broadcast traffic, enhances security by isolating network segments, and allows more efficient use of IP address space. Subnetting is done by borrowing bits from the host portion of an IP address to create a subnet mask.

55. How many usable host addresses are available in a /24 subnet?

  1. 256
  2. 255
  3. 254
  4. 252

Answer : C
Explanation: A /24 subnet (255.255.255.0) has 8 host bits, giving 2⁸ = 256 total addresses. However, the first address is the network address and the last is the broadcast address, both of which cannot be assigned to hosts. This leaves 256 – 2 = 254 usable host addresses. This formula (2ⁿ – 2) applies to any subnet calculation.

56. What is the TCP three-way handshake?

  1. A process where three routers exchange routing information
  2. A connection establishment process using SYN, SYN-ACK, and ACK packets
  3. A method to encrypt data using three keys
  4. A technique to divide data into three equal packets

Answer : B
Explanation: The TCP three-way handshake is the process TCP uses to establish a reliable connection before data transfer. Step 1 — the client sends a SYN (synchronize) packet to the server. Step 2 — the server responds with SYN-ACK (synchronize-acknowledge). Step 3 — the client sends an ACK (acknowledge) to confirm. After this, the connection is established and data transfer begins.

57. What is packet switching in computer networks?

  1. A method where a dedicated path is reserved between sender and receiver for the entire communication
  2. A method where data is broken into packets that are transmitted independently and reassembled at the destination
  3. A method of switching that only works on wireless networks
  4. A technique used exclusively in telephone networks

Answer : B
Explanation: In packet switching, data is broken into small units called packets. Each packet is transmitted independently and may take different routes through the network. They are reassembled at the destination. The internet uses packet switching. This is more efficient than circuit switching (used in traditional telephone networks), which reserves a dedicated path for the entire duration of communication.

58. Which layer of the OSI model handles logical addressing and routing of packets?

  1. Data Link Layer
  2. Transport Layer
  3. Network Layer
  4. Session Layer

Answer : C
Explanation: The Network Layer (Layer 3) is responsible for logical addressing (IP addressing), routing packets from source to destination across multiple networks, and inter-networking. Routers operate at this layer. The key protocols at this layer include IP (Internet Protocol), ICMP, OSPF, and RIP.

59. What is the purpose of ICMP (Internet Control Message Protocol)?

  1. To transfer files between hosts
  2. To send error messages and operational information about network conditions
  3. To assign IP addresses to devices
  4. To encrypt data between two hosts

Answer : B
Explanation: ICMP (Internet Control Message Protocol) is used by network devices, especially routers, to send error messages and operational information. For example, it reports when a destination is unreachable, when a packet’s TTL (Time to Live) has expired, or when a packet is too large. The popular “ping” command uses ICMP echo request and echo reply messages to test network connectivity.

60. What does the “ping” command test in networking?

  1. The speed of a file download
  2. The connectivity and round-trip time between two network devices
  3. The number of devices connected to a network
  4. The encryption strength of a connection

Answer : B
Explanation: The ping command uses ICMP echo request and echo reply messages to test whether a remote host is reachable and to measure the round-trip time (RTT) in milliseconds. It is one of the most commonly used network troubleshooting tools. A successful ping confirms basic IP connectivity. A failed ping may indicate network issues, firewall rules, or that the host is offline.

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