Topic in Computer Networks & Cloud Computing
A computer network is a set of interconnected devices that share resources and exchange data using agreed protocols over wired or wireless links. MCQs on the fundamentals compare LAN, MAN and WAN by geographic scope, name topologies such as bus, star, ring and mesh, and ask what hubs, switches, routers, modems and network interface cards do. A large share focuses on layering: the seven OSI layers and their protocol data units, how they map onto the four-layer TCP/IP model, and which standards bodies like IEEE define Ethernet. You should also recognise CSMA/CD, ICMP messages and the difference between a layer-3 switch and a router.
Below are 30 practice questions from a pool of 210 Computer Networks MCQs, one of 10 topics in Computer Networks & Cloud Computing. Each shows the correct answer with an explanation; when you are ready, take a timed quiz to test recall under exam conditions.
Each question below shows the correct answer with a full explanation. Use these to build conceptual understanding before attempting a timed quiz.
Q1. What type of network covers a small geographical area like a single building?
A Local Area Network (LAN) covers a small geographical area such as a single building, office, or campus.
Q2. Which topology connects all devices to a single central cable?
In bus topology, all devices are connected to a single central cable called the bus or backbone.
Q3. How many layers does the OSI model have?
The OSI (Open Systems Interconnection) model has 7 layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.
Q4. Which device operates at the physical layer to regenerate signals?
A repeater operates at the physical layer and regenerates weakened signals to extend the reach of a network.
Q5. Which network topology provides the highest redundancy?
Full mesh topology provides the highest redundancy because every device is connected to every other device, offering multiple paths for data.
Q6. Which layer of the OSI model is responsible for routing?
The network layer (Layer 3) is responsible for routing packets from source to destination across multiple networks.
Q7. What does WAN stand for?
WAN stands for Wide Area Network, which spans large geographical areas such as countries or continents.
Q8. In which switching technique is a dedicated path established before data transfer?
In circuit switching, a dedicated communication path is established between sender and receiver before data transfer begins. Traditional telephone networks use circuit switching.
Q9. Which networking device connects two different networks and operates at the network layer?
A router connects two or more different networks and operates at the network layer (Layer 3) to forward packets between networks.
Q10. What is the TCP/IP model also known as?
The TCP/IP model is also known as the Internet model because it is the protocol suite that powers the Internet.
Q11. In a full mesh topology with n devices, how many links are required?
In a full mesh topology, every device connects to every other device. The number of links needed is n(n-1)/2.
Q12. Which layer of the OSI model handles data encryption and compression?
The Presentation layer (Layer 6) is responsible for data encryption, decryption, compression, and translation between different data formats.
Q13. What is the main advantage of packet switching over circuit switching?
Packet switching is more efficient because it allows multiple communications to share the same network resources, unlike circuit switching which dedicates resources to a single connection.
Q14. Which TCP/IP layer corresponds to the OSI network layer?
The Internet layer in the TCP/IP model corresponds to the Network layer in the OSI model. Both handle logical addressing and routing.
Q15. What type of switching does ATM (Asynchronous Transfer Mode) use?
ATM uses cell switching, which transmits data in fixed-size cells of 53 bytes (5 bytes header + 48 bytes payload).
Q16. Which organization is responsible for defining the Ethernet standard (IEEE 802.3)?
IEEE (Institute of Electrical and Electronics Engineers) defines LAN standards including Ethernet (802.3), Wi-Fi (802.11), and others.
Q17. What is the function of the session layer in the OSI model?
The Session layer (Layer 5) manages dialog control, establishing, maintaining, and synchronizing communication sessions between applications.
Q18. In packet switching, what is the difference between datagram and virtual circuit approaches?
In virtual circuit switching, a logical path is established before data transfer. In datagram switching, each packet is independently routed and may take different paths.
Q19. A hub operates at which layer of the OSI model?
A hub operates at the Physical layer (Layer 1). It simply regenerates and broadcasts incoming signals to all ports without any intelligence.
Q20. What is the difference between a bridge and a switch?
Both operate at Layer 2, but switches can process multiple frames simultaneously using hardware-based forwarding, while bridges typically handle one frame at a time using software.
Q21. In the OSI model, at which layer does the PDU (Protocol Data Unit) change from 'segment' to 'packet'?
The Transport layer PDU is called a segment. When it is passed down to the Network layer, the PDU becomes a packet (or datagram).
Q22. Which RFC defines the Internet Protocol version 4 (IPv4)?
RFC 791 defines IPv4. RFC 793 defines TCP, RFC 2460 defined IPv6 (later obsoleted by RFC 8200), and RFC 768 defines UDP.
Q23. What problem does the Spanning Tree Protocol (STP) solve in switched networks?
STP prevents broadcast storms and switching loops by creating a loop-free logical topology from a physical topology that may contain loops.
Q24. In a hierarchical network design, what is the role of the distribution layer?
The distribution layer acts as a boundary between the access and core layers, providing policy-based connectivity, routing, filtering, and QoS.
Q25. What is the key concept behind Software-Defined Networking (SDN)?
SDN separates the control plane (decision-making) from the data plane (packet forwarding), allowing centralized, programmable network management.
Q26. What is the purpose of MPLS (Multi-Protocol Label Switching) in networking?
MPLS uses short labels instead of long IP addresses for forwarding decisions, enabling faster packet forwarding and traffic engineering capabilities.
Q27. In network performance, what is jitter?
Jitter is the variation in the delay of received packets. High jitter is problematic for real-time applications like VoIP and video conferencing.
Q28. What distinguishes a Layer 3 switch from a traditional router?
A Layer 3 switch performs routing functions using hardware (ASICs) rather than software, providing wire-speed routing performance within LANs.
Q29. In the context of Quality of Service (QoS), what does DiffServ provide?
DiffServ (Differentiated Services) classifies traffic into service classes using the DSCP (Differentiated Services Code Point) field in the IP header for scalable QoS.
Q30. What is the main purpose of Network Function Virtualization (NFV)?
NFV replaces dedicated network appliances (firewalls, load balancers, etc.) with software-based implementations running on commodity servers, reducing costs and increasing flexibility.
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