Computer networks are the backbone of modern communication and technology. From sending emails to managing cloud services, networks make it all possible. To succeed in exams, competitive tests, or job interviews, mastering networking concepts is essential.
In this collection, we have compiled the most important computer network questions with answers and explanations. Each question is carefully designed to cover fundamental and advanced topics like OSI model, IP addressing, routing protocols, and network devices.
By practicing these networking MCQs with answers, you can:
Set-1
1. The computer network is
Explain: A network can be wired (with cable) or wireless (without cable).
2. FDDI used which type of physical topology?
Explain: FDDI (Fiber Distributed Data Interface) uses a dual-ring topology.
3. FTP stands for
Explain: FTP is the standard protocol for transferring files across networks.
4. Ethernet system uses which of the following technology.
Explain: Ethernet commonly uses bus technology for data transmission.
5. Which of the following are the network services?
Explain: Networks provide file, print, database and other services.
6. If all devices are connected to a central hub, then topology is called
Explain: A star topology connects all devices to a central hub.
7. FDDI stands for
Explain: FDDI is a high-speed network standard based on optical fiber.
8. Which of the following is an application layer service?
Explain: All listed services belong to the Application Layer.
9. Which is the main function of transport layer?
Explain: The transport layer ensures reliable end-to-end communication.
10. The ............. layer changes bits onto electromagnetic signals.
Explain: The physical layer deals with signals and bit transmission.
11. In mesh topology, relationship between one device and another is ..............
Explain: In mesh topology, devices are directly connected to each other in peer-to-peer form.
12. The performance of data communications network depends on ..............
Explain: Network performance is influenced by users, hardware/software, and transmission.
13. Find out the OSI layer, which performs token management.
Explain: Token management is handled by the session layer in OSI model.
14. The name of the protocol which provides virtual terminal in TCP/IP model is.
Explain: Telnet provides a virtual terminal service in TCP/IP model.
15. The layer one of the OSI model is
Explain: The first OSI layer is the physical layer.
16. What is the name of the network topology in which there are bi-directional links between each possible node?
Explain: A mesh topology has direct bi-directional links between all nodes.
17. What is the commonly used unit for measuring the speed of data transmission?
Explain: Baud is the standard unit for symbol rate in data transmission.
18. Which of the communication modes support two way traffic but in only one direction at a time?
Explain: Half-duplex allows two-way communication, but only one side at a time.
19. The loss in signal power as light travels down the fiber is called .............
Explain: Attenuation is the reduction in signal power over distance.
20. Which of the following TCP/IP protocols is used for transferring files from one machine to another?
Explain: FTP (File Transfer Protocol) is used for transferring files across networks.
Set-2
1. A network that needs human beings to manually route signals is called....
Explain: Telephone-switched networks require manual routing of signals.
2. TCP/IP .................. layer corresponds to the OSI model's top three layers.
Explain: TCP/IP’s application layer maps to OSI's application, presentation, and session layers.
3. Which of the transport layer protocols is connectionless?
Explain: UDP is a connectionless transport protocol, unlike TCP.
4. Which of the following applications allows a user to access and change remote files without actual transfer?
Explain: NFS (Network File System) lets users work with remote files without transferring them.
5. The data unit in the TCP/IP layer is called a .....
Explain: In TCP/IP, the data unit is called a frame at the network interface layer.
6. DNS can obtain the .................. of a host if its domain name is known and vice versa.
Explain: DNS resolves domain names to IP addresses and vice versa.
7. Which of the following OSI layers correspond to TCP/IP's application layer?
Explain: TCP/IP’s application layer maps to OSI’s application, session, and presentation layers.
8. Devices on one network can communicate with devices on another network via a .......
Explain: Gateways connect and allow communication between different networks.
9. A communication device that combines transmissions from several I/O devices into one line is a
Explain: A multiplexer combines signals from multiple devices onto a single line.
10. Which layer of the OSI determines the interface of the system with the user?
Explain: The application layer provides user interfaces to the network.
11. Which of the following TCP/IP protocols is used for transferring files from one machine to another?
Explain: FTP (File Transfer Protocol) is designed to transfer files across systems.
12. In which OSI layers does the FDDI protocol operate?
Explain: FDDI works at both physical and data link layers.
13. In FDDI, data normally travel on ..................
Explain: FDDI uses a dual ring but normally data flows through the primary ring.
14. The ............ layer of OSI model can use the trailer of the frame for error detection.
Explain: Error detection (via CRC) is done in the data link layer using frame trailers.
15. In a ................ topology, if there are n devices in a network, each device has n-1 ports for cables.
Explain: In mesh, each device connects to every other device, requiring (n-1) ports per node.
16. Another name for Usenet is
Explain: Usenet is a distributed discussion system also called Newsgroups.
17. The standard suite of protocols used by the Internet, Intranets, extranets and some other networks.
Explain: TCP/IP is the standard protocol suite for Internet and related networks.
18. State whether the following is True or False.
i) In bus topology, heavy Network traffic slows down the bus speed.
ii) It is multipoint configuration.
Explain: Bus topology slows with traffic and is multipoint configuration.
19. Which of the following is the logical topology?
Explain: Star topology is a logical configuration, though physically centralized.
20. Which of the following is/are the drawbacks of Ring Topology?
Explain: In ring topology, failure of one node or changing nodes disturbs the network.
Set-3
41. In which of the following topology, all the nodes are connected to a single cable?
Explain: In bus topology, all nodes are connected through a single backbone cable.
42. In star topology, each device is connected to a ………
Explain: In star topology, all devices connect to a central hub or switch.
43. Which topology requires a multipoint connection?
Explain: Bus topology uses a multipoint connection, sharing a single cable among all devices.
44. What is the main advantage of a ring topology?
Explain: In a ring, each node gets equal opportunity for data transmission.
45. In mesh topology, the number of cables required to connect n devices is ………
Explain: Mesh requires a dedicated link between every pair of devices.
46. The physical layer of OSI model is concerned with ………
Explain: The physical layer deals with the transmission of raw bits over a channel.
47. Which topology is the most reliable?
Explain: Mesh provides multiple paths, making it highly reliable.
48. The presentation layer is responsible for ………
Explain: Presentation layer handles translation, compression, and encryption of data.
49. The transport layer is responsible for ………
Explain: Transport layer ensures end-to-end, process-to-process delivery of data.
50. The network layer is responsible for ………
Explain: The network layer is responsible for routing and delivery between source and destination.
Set-4
51. The data link layer is responsible for ………
Explain: Data link layer handles delivery of frames between directly connected nodes.
52. Which layer is responsible for error detection and correction?
Explain: Error detection/correction is managed at the data link layer.
53. Which layer is responsible for line configuration?
Explain: The physical layer defines line configuration (point-to-point or multipoint).
54. In OSI model, encryption and decryption are functions of ……… layer.
Explain: The presentation layer performs translation, encryption and compression.
55. Which topology requires a central controller or hub?
Explain: Star topology requires a central hub or controller.
56. Which topology provides a direct connection between every pair of devices?
Explain: In a mesh topology, each device is directly connected to all others.
57. In OSI model, the session layer is responsible for ………
Explain: Session layer manages dialog control and synchronization.
58. Which OSI layer is responsible for translation of data?
Explain: Presentation layer translates data between application and network formats.
59. Which OSI layer establishes, manages, and terminates connections?
Explain: Session layer manages connection setup, maintenance, and termination.
60. Which OSI layer is responsible for routing?
Explain: Routing of packets is a function of the network layer.
61. The unit of data at the data link layer is called ………
Explain: Data link layer encapsulates packets into frames for transmission.
62. The unit of data at the network layer is called ………
Explain: The network layer delivers data in the form of packets.
63. The unit of data at the transport layer is called ………
Explain: At the transport layer, data is segmented into smaller units called segments.
64. The unit of data at the physical layer is called ………
Explain: The physical layer deals with transmission of raw bits.
65. The unit of data at the application layer is called ………
Explain: Application layer communicates using complete messages.
66. Which OSI layer is responsible for error-free delivery of data?
Explain: The transport layer ensures error-free, end-to-end delivery.
67. Which OSI layer provides end-to-end communication services for applications?
Explain: Transport layer provides end-to-end communication between applications.
68. Which OSI layer is responsible for data compression?
Explain: Compression and decompression of data is done at the presentation layer.
69. Which OSI layer is responsible for defining electrical and physical specifications of the data connection?
Explain: Physical layer defines hardware, electrical, and mechanical specifications.
70. Which OSI layer is responsible for logical addressing?
Explain: Logical addressing (IP addresses) is provided by the network layer.
Set-5
71. The OSI model consists of ……… layers.
Explain: The OSI model is divided into 7 layers from physical to application.
72. TCP belongs to which OSI layer?
Explain: TCP operates at the transport layer of the OSI model.
73. HTTP works at which OSI layer?
Explain: HTTP is an application layer protocol for communication on the web.
74. Which OSI layer is responsible for flow control?
Explain: Flow control is managed by the transport layer to prevent data loss.
75. IP addressing belongs to which OSI layer?
Explain: Logical addressing (IP addresses) works at the network layer.
76. SMTP is used for ………
Explain: SMTP (Simple Mail Transfer Protocol) is used to send emails.
77. FTP is used for ………
Explain: FTP (File Transfer Protocol) is used to upload and download files.
78. TELNET is used for ………
Explain: TELNET allows a user to log in remotely to another computer.
79. DNS is used to ………
Explain: DNS translates human-friendly domain names into IP addresses.
80. Which layer of OSI model is responsible for error detection?
Explain: Error detection in frames is handled by the data link layer.
81. Which device operates at the network layer?
Explain: Routers work at the network layer to forward packets based on IP addresses.
82. Which device operates at the data link layer?
Explain: Switches operate at the data link layer using MAC addresses.
83. Which device operates at the physical layer?
Explain: Hubs simply forward bits and operate at the physical layer.
84. Which protocol is used to transfer files over the Internet securely?
Explain: SFTP (Secure FTP) uses SSH to provide secure file transfer.
85. Which of the following is a connectionless protocol?
Explain: UDP is a connectionless transport protocol.
86. Which of the following is a connection-oriented protocol?
Explain: TCP establishes a reliable connection before transmitting data.
87. Which of the following is an IP address class not used in practice?
Explain: Class E addresses are reserved for experimental purposes, not for public use.
88. IPv6 address size is ………
Explain: IPv6 addresses are 128-bit long, written in hexadecimal.
89. Which of the following is used to find the shortest path in routing?
Explain: Dijkstra’s algorithm is widely used in routing to find shortest paths.
90. Which of the following is not an application layer protocol?
Explain: TCP is a transport layer protocol, not application layer.
Set-6
91. Which of the following is used to uniquely identify a device on a network?
Explain: Every device on a network is uniquely identified using its IP address.
92. Which layer of OSI model ensures reliable transmission of data?
Explain: The transport layer provides reliability with error detection and correction.
93. ICMP is used for ………
Explain: ICMP (Internet Control Message Protocol) reports errors and network diagnostics (e.g., ping).
94. Which protocol is used to securely browse websites?
Explain: HTTPS encrypts communication using SSL/TLS for secure browsing.
95. Which device connects two different networks?
Explain: A router connects two or more different networks.
96. ARP is used for ………
Explain: ARP (Address Resolution Protocol) finds the MAC address for a given IP.
97. RARP is used for ………
Explain: RARP (Reverse ARP) finds the IP address for a given MAC.
98. Which protocol provides host-to-host delivery?
Explain: TCP ensures end-to-end, host-to-host delivery of data.
99. Which of the following protocols is used for email retrieval?
Explain: POP3 (Post Office Protocol v3) is used for retrieving emails from the server.
100. Which protocol is used for sending email?
Explain: SMTP (Simple Mail Transfer Protocol) is used for sending emails.
101. Which layer of OSI model provides encryption and decryption?
Explain: Presentation layer is responsible for data formatting, encryption, and compression.
102. Which of the following is not a valid IP address class?
Explain: Only Class A to E exist; Class F does not exist.
103. Which device breaks up collision domains?
Explain: Switches break up collision domains, while hubs do not.
104. Which device breaks up broadcast domains?
Explain: Routers separate broadcast domains.
105. Which protocol is used to assign IP addresses automatically?
Explain: DHCP automatically assigns IP addresses to hosts.
106. The maximum length of an IPv4 address is ………
Explain: IPv4 addresses are 32-bit long.
107. The maximum length of an IPv6 address is ………
Explain: IPv6 addresses are 128-bit long.
108. Which of the following is a Layer 4 protocol?
Explain: TCP and UDP both operate at the transport layer (Layer 4).
109. Which of the following is a Layer 3 protocol?
Explain: Internet Protocol (IP) works at the network layer (Layer 3).
110. Which of the following is not a Layer 7 protocol?
Explain: TCP is a transport layer protocol, not an application (Layer 7) protocol.
Set-7
111. Which of the following protocols is used for remote login?
Explain: TELNET is a protocol used for remote login into another computer over a network.
112. Which protocol is used to transfer files between computers?
Explain: FTP (File Transfer Protocol) is used for transferring files between computers.
113. Which of the following is a connectionless protocol?
Explain: UDP (User Datagram Protocol) is connectionless and faster but less reliable than TCP.
114. Which of the following protocols is used for network management?
Explain: SNMP (Simple Network Management Protocol) is used for network monitoring and management.
115. Which device is used to regenerate signals in a network?
Explain: Repeaters are used to regenerate weak signals to extend the length of networks.
116. Which device operates at both Layer 2 and Layer 3 of the OSI model?
Explain: A multilayer switch can operate at both data link (Layer 2) and network layer (Layer 3).
117. Which of the following is a distance vector routing protocol?
Explain: RIP (Routing Information Protocol) is a classic distance vector protocol.
118. Which of the following is a link state routing protocol?
Explain: OSPF (Open Shortest Path First) is a widely used link state routing protocol.
119. Which routing protocol is used on the Internet for inter-domain routing?
Explain: BGP (Border Gateway Protocol) is used for inter-domain routing on the Internet.
120. Which of the following protocols provides error reporting?
Explain: ICMP is used for error reporting and diagnostic functions (e.g., ping).
121. The protocol used to resolve IP addresses to MAC addresses is?
Explain: ARP maps IP addresses to corresponding MAC addresses on a local network.
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