1. What best defines a computer network?
Difficulty: EasyType: MCQTopic: network fundamentals
- A collection of independent computers connected to share resources and data
- A single computer performing multiple operations
- A group of printers sharing the same paper source
- Only the Internet
A computer network connects two or more computing devices so they can exchange data, share resources, and communicate efficiently. Networks can be small like a home LAN or large like the Internet, but the basic goal remains collaboration and resource sharing.
Correct Answer: A collection of independent computers connected to share resources and data
2. Which network topology connects all devices to a single central device?
Difficulty: MediumType: MCQTopic: network fundamentals
- Ring topology
- Bus topology
- Star topology
- Mesh topology
In a star topology, all devices connect to a central hub or switch. This design makes troubleshooting easier since a failure in one cable affects only one device. However, if the central hub fails, the whole network can go down.
Correct Answer: Star topology
3. How many layers are there in the OSI reference model?
Difficulty: MediumType: MCQTopic: network models
The OSI (Open Systems Interconnection) model has seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Each layer provides services to the layer above it and hides complexity from lower layers. Knowing the OSI model is essential in networking interviews.
Correct Answer: 7
4. Describe the layers of the TCP/IP model and compare it with the OSI model.
Difficulty: MediumType: SubjectiveTopic: network models
The TCP/IP model has four layers: Application, Transport, Internet, and Network Access. The Application layer handles user services like HTTP and FTP. The Transport layer provides end-to-end communication using TCP or UDP. The Internet layer handles routing and addressing through IP. The Network Access layer deals with physical transmission. Compared to the OSI model, TCP/IP merges several OSI layers into fewer practical ones. OSI is more conceptual, while TCP/IP reflects how real networks function.
5. What is a protocol in computer networking?
Difficulty: EasyType: MCQTopic: network fundamentals
- A physical wire that connects computers
- A set of rules governing communication between network devices
- A type of IP address
- A brand of router
A protocol is a formal set of rules and standards that define how data is transmitted, formatted, and received across a network. Examples include HTTP, FTP, TCP, and IP. Protocols ensure that devices from different vendors can communicate effectively.
Correct Answer: A set of rules governing communication between network devices
6. Which of the following best describes a WAN (Wide Area Network)?
Difficulty: EasyType: MCQTopic: network fundamentals
- Connects devices within a single building
- Connects computers over a small area like a home or office
- Connects multiple LANs across cities or countries
- A network without cables
A WAN connects multiple local area networks over a wide geographic area using leased lines or satellites. The Internet itself is the largest WAN. Interviews often test your ability to distinguish LAN, MAN, and WAN by scale and technology.
Correct Answer: Connects multiple LANs across cities or countries
7. Explain the concept of encapsulation and decapsulation in networking.
Difficulty: MediumType: SubjectiveTopic: network models
Encapsulation is the process of wrapping data with protocol information at each layer of the OSI or TCP/IP model before transmission. For example, the transport layer adds headers like port numbers, and the network layer adds IP addresses. Decapsulation is the reverse process where the receiving device removes these headers layer by layer to retrieve the original data. Encapsulation ensures that each layer can process information independently and reliably, making communication structured and modular.
8. Which statement correctly distinguishes between a MAC address and an IP address?
Difficulty: MediumType: MCQTopic: ip addressing
- MAC address identifies a device on the Internet; IP address identifies hardware
- MAC address is used only for wireless networks; IP address for wired networks
- MAC address identifies a hardware interface; IP address identifies logical network location
- They both identify the same thing
A MAC (Media Access Control) address uniquely identifies a device’s network interface card at the data link layer, while an IP address identifies a device’s logical position in a network. MAC addresses are fixed by hardware manufacturers; IP addresses can change dynamically through DHCP.
Correct Answer: MAC address identifies a hardware interface; IP address identifies logical network location
9. Differentiate between a switch and a router. When would you use each?
Difficulty: MediumType: SubjectiveTopic: network devices
A switch operates at the data link layer and is used to connect multiple devices within the same network (LAN). It uses MAC addresses to forward frames. A router works at the network layer and connects multiple networks, using IP addresses to forward packets. You’d use a switch to expand a local network and a router to link different networks or connect to the Internet. In modern environments, routers often include switch functionality for small office setups.
10. Which statement correctly explains the difference between bandwidth and latency?
Difficulty: MediumType: MCQTopic: physical layer & transmission
- Bandwidth measures delay; latency measures capacity
- Bandwidth measures capacity; latency measures delay
- Both measure delay
- Both measure capacity
Bandwidth refers to how much data can be transmitted in a given time, usually measured in bits per second. Latency is the time delay between sending a request and receiving a response. For example, a high-bandwidth but high-latency link can transfer large files fast but respond slowly to small interactive requests.
Correct Answer: Bandwidth measures capacity; latency measures delay
11. Walk through how data flows from one computer to another across a network using the OSI model perspective.
Difficulty: HardType: SubjectiveTopic: network fundamentals
When data moves between two computers, it starts at the Application layer where user data (for example a message) is created. It passes down the stack through the Presentation layer (which may encrypt or compress it), then through the Session layer to maintain a logical connection. At the Transport layer, the message is broken into segments, and port numbers are added. The Network layer adds source and destination IP addresses, creating packets. The Data Link layer frames the packets and adds MAC addresses for local delivery. Finally, the Physical layer converts frames into electrical or optical signals. The receiver performs decapsulation in the reverse order. This layered approach ensures modular design and interoperability.
12. Which device operates primarily at the Data Link layer of the OSI model?
Difficulty: EasyType: MCQTopic: network devices
- Router
- Switch
- Gateway
- Repeater
A switch works at the Data Link layer (Layer 2). It uses MAC addresses to forward frames between devices on the same network. Routers operate at Layer 3, while repeaters operate at Layer 1. Knowing device-to-layer mapping is a common quick-fire interview question.
Correct Answer: Switch
13. Explain the client-server architecture and how it differs from peer-to-peer networking.
Difficulty: MediumType: SubjectiveTopic: network fundamentals
In a client-server architecture, clients request services and servers provide them — for example, a web browser requesting data from a web server. The server is centralised, controlling data and authentication. In a peer-to-peer network every device can act as both client and server, sharing resources directly. Client-server is more scalable and easier to secure, while peer-to-peer is decentralised and better for small networks or distributed sharing. Understanding this difference helps answer conceptual design questions in interviews.
14. What is the primary function of the Physical Layer in the OSI model?
Difficulty: EasyType: MCQTopic: physical layer & transmission
- To handle logical addressing and routing
- To manage data encryption and compression
- To transmit raw bits over a physical medium
- To provide reliable end-to-end communication
The Physical Layer is responsible for the actual transmission of raw bits over a communication channel. It defines electrical, optical, and mechanical characteristics such as voltage levels, pin configurations, data rates, and cable types. This layer ensures that bits are physically moved from one node to another.
Correct Answer: To transmit raw bits over a physical medium
15. Which statement best describes an analog signal?
Difficulty: EasyType: MCQTopic: physical layer & transmission
- It represents data as a series of discrete values
- It varies continuously with time and amplitude
- It can only represent binary data
- It is unaffected by noise
An analog signal changes smoothly over time, representing data through variations in amplitude or frequency. Examples include voice and radio waves. In contrast, digital signals use discrete values (0s and 1s). Understanding signal behavior helps explain how data is transmitted physically.
Correct Answer: It varies continuously with time and amplitude
16. Why are digital signals often preferred over analog signals in modern networks?
Difficulty: MediumType: MCQTopic: physical layer & transmission
- They use more bandwidth but are easier to interpret
- They are immune to noise
- They are less affected by noise and can be regenerated easily
- They do not require any medium for transmission
Digital signals can be cleaned and regenerated at intermediate points without distortion, making them more reliable. While analog signals degrade over distance, digital systems allow error detection and correction. That’s why digital communication dominates in modern networking systems.
Correct Answer: They are less affected by noise and can be regenerated easily
17. Differentiate between guided and unguided transmission media with examples.
Difficulty: MediumType: SubjectiveTopic: physical layer & transmission
Guided media use a physical path to transmit data signals, such as copper wires or fiber-optic cables. Examples include twisted pair, coaxial, and optical fiber. They are reliable and less prone to interference. Unguided media, on the other hand, use air, water, or vacuum as the transmission medium. Examples include radio waves, microwaves, and infrared. They are flexible and support mobility but are more susceptible to interference and signal loss. Mentioning trade-offs between cost, speed, and range strengthens your interview answer.
18. What is the main advantage of twisting wires in a twisted pair cable?
Difficulty: MediumType: MCQTopic: physical layer & transmission
- It increases the cable’s diameter
- It reduces electromagnetic interference and crosstalk
- It makes the signal travel faster
- It reduces the need for shielding
In twisted pair cables, each pair of wires is twisted together to reduce electromagnetic interference from nearby cables or external sources. The twisting ensures that interference affects both wires equally, allowing the receiver to cancel it out. This makes it a cost-effective and widely used medium for LANs.
Correct Answer: It reduces electromagnetic interference and crosstalk
19. Explain how data is transmitted through a fiber-optic cable and mention its advantages.
Difficulty: MediumType: SubjectiveTopic: physical layer & transmission
In fiber optics, data is transmitted as pulses of light using a laser or LED source. The light travels through a core surrounded by cladding that reflects light inward through total internal reflection. Advantages include very high bandwidth, long-distance transmission, immunity to electromagnetic interference, and better security because light signals are difficult to tap. However, they are expensive and fragile compared to copper cables. In interviews, highlight fiber optics when asked about high-speed backbone connections.
20. What does 'bandwidth' mean in the context of data transmission?
Difficulty: MediumType: MCQTopic: physical layer & transmission
- The physical length of the cable
- The range of frequencies a channel can carry
- The speed of light in fiber
- The delay of data packets
Bandwidth is the difference between the highest and lowest frequencies a channel can transmit. It represents the data-carrying capacity of a communication medium. A higher bandwidth allows more data to be sent per second, resulting in faster transmission speeds.
Correct Answer: The range of frequencies a channel can carry
21. What is attenuation and how can it be minimized in network transmission?
Difficulty: MediumType: SubjectiveTopic: physical layer & transmission
Attenuation is the loss of signal strength as it travels through a transmission medium. It can be caused by distance, poor cable quality, or environmental factors. To minimize attenuation, use repeaters or amplifiers at intervals, use high-quality cables (like optical fiber), and maintain proper cable shielding. In digital systems, repeaters regenerate the signal, eliminating accumulated noise. Mentioning both hardware and design solutions shows practical understanding.
22. Which of the following can cause errors during data transmission?
Difficulty: MediumType: MCQTopic: physical layer & transmission
- Thermal noise
- Propagation delay
- Network congestion
- All of the above
Errors in transmission can arise from thermal noise (random electrical fluctuations), propagation delays, or congestion in intermediate nodes. While some issues are physical (noise, attenuation), others are network-level (buffer overflow). Identifying these helps design robust systems with error detection and correction.
Correct Answer: All of the above
23. What is modulation in data communication?
Difficulty: MediumType: MCQTopic: physical layer & transmission
- The process of filtering unwanted frequencies
- The process of varying a carrier signal to transmit data
- The process of encoding binary to text
- The process of encrypting data packets
Modulation is used to encode digital or analog data onto a carrier signal by varying its amplitude, frequency, or phase. It allows data to travel efficiently over long distances and makes better use of the available bandwidth. Common techniques include AM, FM, and PM.
Correct Answer: The process of varying a carrier signal to transmit data
24. Differentiate between data rate and baud rate with an example.
Difficulty: HardType: SubjectiveTopic: physical layer & transmission
Data rate refers to the number of bits transmitted per second, while baud rate is the number of signal units or symbols transmitted per second. If each signal unit represents more than one bit, then data rate = baud rate × number of bits per symbol. For example, if a signal transmits two bits per symbol at a baud rate of 1200, the data rate is 2400 bps. Many students confuse them, but in interviews, emphasizing their mathematical relationship earns clarity points.
25. Which of the following is NOT a common type of noise in communication systems?
Difficulty: MediumType: MCQTopic: physical layer & transmission
- Thermal noise
- Impulse noise
- Cross-talk
- Frame noise
Common noise types include thermal, impulse, cross-talk, and intermodulation noise. ‘Frame noise’ isn’t a recognized category. Understanding noise helps in applying filters, error correction, and improving reliability. It’s a classic physical layer interview topic.
Correct Answer: Frame noise
26. Explain multiplexing and describe one type used in computer networks.
Difficulty: HardType: SubjectiveTopic: physical layer & transmission
Multiplexing is a technique that allows multiple signals to share a single transmission medium efficiently. For example, Frequency Division Multiplexing (FDM) divides the available bandwidth into distinct frequency channels for each signal. Time Division Multiplexing (TDM) divides the time into slots assigned to each signal sequentially. Multiplexing maximizes bandwidth usage and reduces infrastructure cost. Knowing when to use FDM, TDM, or WDM (in optical fiber) is a common placement question.
27. Which of the following is the main responsibility of the Data Link Layer?
Difficulty: EasyType: MCQTopic: data link & ethernet
- Routing packets between networks
- Transmitting raw bits across the channel
- Framing, error detection, and reliable node-to-node delivery
- Application-level encryption
The Data Link Layer ensures reliable transfer of frames between two nodes connected by a physical link. It groups bits into frames, adds headers and trailers, detects errors, and sometimes handles retransmission. This layer bridges the gap between the raw transmission of bits and structured network communication.
Correct Answer: Framing, error detection, and reliable node-to-node delivery
28. What is framing and why is it needed in the Data Link Layer?
Difficulty: MediumType: SubjectiveTopic: data link & ethernet
Framing is the process of dividing a stream of bits into manageable units called frames. Each frame carries synchronization information, addressing fields, and error-control bits. Without framing, the receiver cannot determine where one message ends and the next begins. Framing also helps in detecting transmission errors and ensures proper sequencing of data. Common techniques include byte count, flag bytes, and bit stuffing.
29. Which of these techniques is used for error detection?
Difficulty: MediumType: MCQTopic: data link & ethernet
- Stop-and-wait
- CRC
- Sliding window
- Token passing
Cyclic Redundancy Check (CRC) uses polynomial division to detect errors in data frames. It is powerful and widely used in Ethernet and storage systems. The sender appends a computed CRC value to the frame; the receiver recomputes it and checks for mismatches.
Correct Answer: CRC
30. In a simple parity check, what happens if the number of 1s in transmitted data is odd but the parity bit expects even parity?
Difficulty: EasyType: MCQTopic: data link & ethernet
- Error detected
- Transmission is faster
- Error ignored
- Parity bit is skipped
A parity bit is an extra bit added to make the total number of 1s even or odd. If the received data does not match the expected parity rule, an error is detected. Though it cannot correct errors, parity checking provides a quick and inexpensive error-detection method.
Correct Answer: Error detected
31. Explain how the Hamming Code works for error detection and correction.
Difficulty: HardType: SubjectiveTopic: data link & ethernet
Hamming Code uses redundant parity bits placed at specific positions in a binary data block to both detect and correct single-bit errors. Each parity bit covers certain data bits based on binary positions. When the receiver recomputes parity, a mismatch indicates which bit is corrupted. The bit is flipped to recover the correct data. Hamming Code is widely used in memory systems and demonstrates a clever trade-off between redundancy and reliability.
32. What is the purpose of flow control in the Data Link Layer?
Difficulty: MediumType: MCQTopic: transport layer
- To limit the number of packets routed per second
- To match the sender’s transmission rate with the receiver’s processing rate
- To reduce routing loops
- To encrypt transmitted data
Flow control ensures that a fast sender does not overwhelm a slower receiver with too much data. It uses mechanisms like Stop-and-Wait and Sliding Window to coordinate data flow. Proper flow control avoids data loss and buffer overflow.
Correct Answer: To match the sender’s transmission rate with the receiver’s processing rate
33. In Stop-and-Wait ARQ, what happens after sending one frame?
Difficulty: MediumType: MCQTopic: transport layer
- The sender immediately sends another frame
- The sender waits for an acknowledgment before sending the next frame
- The sender resends all frames in the buffer
- The receiver requests retransmission proactively
Stop-and-Wait Automatic Repeat Request ensures reliability by waiting for acknowledgment of each frame before sending the next. If the acknowledgment is not received within a timeout, the sender retransmits the frame. This simplicity makes it reliable but inefficient for high-latency links.
Correct Answer: The sender waits for an acknowledgment before sending the next frame
34. Explain how the Sliding Window Protocol improves efficiency over Stop-and-Wait.
Difficulty: MediumType: SubjectiveTopic: transport layer
The Sliding Window Protocol allows multiple frames to be sent before needing an acknowledgment, increasing channel utilization. The sender maintains a window of unacknowledged frames, and the receiver acknowledges as frames arrive, sliding the window forward. This reduces idle time and maximizes throughput, especially in long-delay networks. Variants include Go-Back-N and Selective Repeat ARQ.
35. In Go-Back-N ARQ, what happens when a frame is lost during transmission?
Difficulty: MediumType: MCQTopic: transport layer
- The sender retransmits only that frame
- The sender retransmits all frames from the lost one onward
- The sender waits indefinitely
- The receiver retransmits lost frames
In Go-Back-N, if a frame or acknowledgment is lost, the sender goes back and retransmits that frame and all subsequent ones. It’s simpler to implement but less efficient than Selective Repeat, which retransmits only the missing frames.
Correct Answer: The sender retransmits all frames from the lost one onward
36. How does Selective Repeat ARQ achieve higher efficiency than Go-Back-N?
Difficulty: MediumType: SubjectiveTopic: transport layer
Selective Repeat ARQ retransmits only the specific frames that are lost or corrupted, not the entire sequence. Both sender and receiver maintain sliding windows and store out-of-order frames. This reduces redundant retransmissions, improving bandwidth usage. However, it requires more memory and complex synchronization to manage multiple acknowledgments.
37. Which media access method is used in traditional Ethernet to detect collisions?
Difficulty: MediumType: MCQTopic: data link & ethernet
- ALOHA
- CSMA/CA
- CSMA/CD
- Token Ring
Carrier Sense Multiple Access with Collision Detection (CSMA/CD) lets devices sense the channel before transmitting and detect collisions if they occur. If a collision is detected, transmission stops, and devices wait a random backoff time before retrying. It was key in early Ethernet but is largely obsolete in switched networks today.
Correct Answer: CSMA/CD
38. What does the MAC address uniquely identify?
Difficulty: EasyType: MCQTopic: data link & ethernet
- A network interface card on a device
- A process in memory
- A TCP connection
- A user account
The Media Access Control (MAC) address is a 48-bit identifier hard-coded into a network card. It uniquely identifies a device on a LAN. MAC addresses enable the Data Link Layer to deliver frames between local devices.
Correct Answer: A network interface card on a device
39. Describe the two sublayers of the Data Link Layer and their responsibilities.
Difficulty: HardType: SubjectiveTopic: network models
The Data Link Layer has two sublayers: the Logical Link Control (LLC) and the Media Access Control (MAC) sublayer. The LLC handles flow control, error detection, and logical addressing to interface with higher layers. The MAC sublayer controls access to the physical transmission medium, handles frame delimiting, and uses MAC addresses for local delivery. This division allows flexible adaptation to different physical media and access protocols.
40. What is the main function of the Network Layer in the OSI model?
Difficulty: EasyType: MCQTopic: network layer
- Reliable frame delivery between two nodes
- Physical bit transmission over cables
- Routing and logical addressing of packets across networks
- Error detection at the physical medium
The Network Layer is responsible for moving packets from the source to the destination across multiple networks. It provides logical addressing (like IP addresses) and selects routes based on algorithms. This layer makes internetwork communication possible.
Correct Answer: Routing and logical addressing of packets across networks
41. What is an IP address used for in networking?
Difficulty: MediumType: MCQTopic: ip addressing
- To physically identify a device’s hardware
- To locate a device logically within a network and identify its host
- To encrypt data packets
- To connect peripherals like printers
An IP address uniquely identifies a host and its network on the Internet or a local network. It enables routers to make forwarding decisions and deliver packets correctly. Think of it as the device’s 'postal address' for digital communication.
Correct Answer: To locate a device logically within a network and identify its host
42. Compare IPv4 and IPv6 in terms of address structure and benefits.
Difficulty: MediumType: SubjectiveTopic: ip addressing
IPv4 uses 32-bit addresses, supporting about 4.3 billion unique addresses, while IPv6 uses 128 bits, allowing practically unlimited addressing. IPv6 simplifies routing and removes the need for NAT, includes built-in IPsec support, and provides auto-configuration features. However, IPv4 remains widely used due to compatibility and legacy systems. In interviews, mention both scalability and transition challenges when comparing them.
43. Why is subnetting used in IP networks?
Difficulty: HardType: MCQTopic: ip addressing
- To merge multiple networks into a single broadcast domain
- To divide a large network into smaller, more manageable sub-networks
- To increase the physical size of a network
- To eliminate the need for routers
Subnetting divides a network into smaller parts to improve management, reduce congestion, and enhance security. Each subnet functions as a smaller network, conserving IP addresses and allowing administrators finer control of traffic routing and broadcast domains.
Correct Answer: To divide a large network into smaller, more manageable sub-networks
44. What does CIDR stand for and what problem does it solve?
Difficulty: MediumType: MCQTopic: ip addressing
- Classless Inter-Domain Routing; reduces routing table size and address waste
- Central Internet Domain Registry; allocates domain names
- Client Internet Data Routing; speeds up DNS lookups
- Connectionless IP Data Relay; improves throughput
CIDR replaced classful addressing by allowing variable-length subnet masks. This provides flexibility in allocating IP ranges and aggregates multiple routes into one, significantly reducing routing table sizes and conserving address space.
Correct Answer: Classless Inter-Domain Routing; reduces routing table size and address waste
45. Explain the difference between static and dynamic routing.
Difficulty: MediumType: SubjectiveTopic: routing
Static routing uses manually configured routes by network administrators. It’s simple, predictable, and secure but lacks adaptability—changes require manual updates. Dynamic routing automatically updates routes using algorithms like RIP or OSPF. It’s scalable and fault-tolerant but requires more processing and introduces slight overhead. In interviews, show you understand trade-offs between control and flexibility.
46. When does packet fragmentation occur in IP networks?
Difficulty: MediumType: MCQTopic: ip addressing
- When a router cannot forward a packet due to mismatched MTU size
- When data is encrypted during transit
- When the source and destination use different protocols
- When duplicate IP addresses exist
Fragmentation happens when a packet is larger than the Maximum Transmission Unit (MTU) of the next network segment. The router splits it into smaller fragments for delivery. IPv6 largely avoids fragmentation by requiring sources to send appropriately sized packets.
Correct Answer: When a router cannot forward a packet due to mismatched MTU size
47. Which IP address class provides the largest number of hosts per network?
Difficulty: EasyType: MCQTopic: ip addressing
- Class A
- Class B
- Class C
- Class D
Class A networks reserve the first 8 bits for the network portion, leaving 24 bits for hosts. This allows around 16 million hosts per network. While efficient for large organizations, classful addressing has been replaced by CIDR in modern networks.
Correct Answer: Class A
48. What is the role of a default gateway in IP networking?
Difficulty: MediumType: SubjectiveTopic: ip addressing
A default gateway is the router that connects a local network to other networks, typically the Internet. When a device wants to send packets to a host outside its local subnet, it forwards them to the gateway’s IP address. The gateway then routes them toward their destination. Understanding this concept shows your grasp of real-world network connectivity.
49. What is the purpose of ICMP in IP networking?
Difficulty: MediumType: MCQTopic: ip addressing
- To establish TCP connections
- To manage IP address allocation
- To report errors and operational information about packet delivery
- To handle application-layer encryption
The Internet Control Message Protocol (ICMP) sends error messages and operational updates, such as when a host is unreachable or a packet’s TTL expires. Tools like ping and traceroute rely on ICMP. Interviewers often test whether you understand its diagnostic role.
Correct Answer: To report errors and operational information about packet delivery
50. What does the Address Resolution Protocol (ARP) do?
Difficulty: MediumType: MCQTopic: ip addressing
- Resolves domain names to IP addresses
- Maps IP addresses to MAC addresses on a local network
- Manages default gateway configurations
- Allocates subnets to different hosts
ARP translates IP addresses into MAC addresses so that data can be sent within a local area network. It enables communication between the Network Layer (IP) and Data Link Layer (MAC). Without ARP, IP packets could not reach their physical destination.
Correct Answer: Maps IP addresses to MAC addresses on a local network
51. What is the function of the Time-to-Live (TTL) field in an IP header?
Difficulty: EasyType: MCQTopic: ip addressing
- Specifies how long a TCP connection remains open
- Indicates the maximum number of hops a packet can traverse before being discarded
- Stores timestamp information for packets
- Defines the time a packet waits in a queue
The TTL field prevents packets from looping endlessly in case of routing errors. Each router decrements TTL by one; when it reaches zero, the packet is discarded and an ICMP ‘Time Exceeded’ message is sent back. TTL protects network stability.
Correct Answer: Indicates the maximum number of hops a packet can traverse before being discarded
52. Given the IP address 192.168.10.0/26, calculate the number of subnets, hosts per subnet, and the valid range of the first subnet.
Difficulty: HardType: SubjectiveTopic: ip addressing
A /26 prefix means 64 addresses per subnet (2⁶). Subtracting network and broadcast addresses, there are 62 usable hosts. Since it’s from a Class C range, the block size is 64. The first subnet runs from 192.168.10.0 to 192.168.10.63, with usable host range 192.168.10.1–192.168.10.62. There are four total subnets (since 256 / 64 = 4). Showing such calculations confidently in interviews demonstrates subnetting fluency.
53. What is routing in computer networks?
Difficulty: EasyType: MCQTopic: routing
- The process of assigning IP addresses to hosts
- The process of determining the path packets take from source to destination
- The process of encrypting network data
- The process of retransmitting lost packets
Routing is the process of selecting paths in a network along which data packets travel from a source to a destination. Routers use routing tables and algorithms to decide the optimal path based on metrics like distance, cost, or congestion.
Correct Answer: The process of determining the path packets take from source to destination
54. Explain how the Distance Vector Routing algorithm works.
Difficulty: MediumType: SubjectiveTopic: routing
In Distance Vector Routing, each router maintains a table listing the shortest distance to every other node and the direction (next hop) to reach it. Routers exchange their tables periodically with neighbors and update routes using the Bellman-Ford algorithm. The simplicity makes it easy to implement but it suffers from slow convergence and routing loops. Protocols like RIP use this approach.
55. Which statement best describes the Link State Routing algorithm?
Difficulty: MediumType: MCQTopic: routing
- Routers exchange only distance vectors with neighbors
- Routers broadcast information about their neighbors to the entire network
- Routers rely on a centralized controller for route computation
- Routers use random paths for load balancing
In Link State Routing, routers discover their neighbors, measure link costs, and flood this information to all other routers. Each router builds a full map of the network and computes the shortest paths using Dijkstra’s algorithm. It converges faster and is more scalable than distance vector routing.
Correct Answer: Routers broadcast information about their neighbors to the entire network
56. Which protocol uses hop count as its primary metric for routing?
Difficulty: MediumType: MCQTopic: routing
The Routing Information Protocol (RIP) uses hop count to determine the shortest path. The maximum allowed hops are 15, meaning larger networks are unsuitable for RIP. Despite its limitations, RIP is widely used in small and academic networks.
Correct Answer: RIP
57. Describe OSPF and explain how it differs from RIP.
Difficulty: MediumType: SubjectiveTopic: routing
Open Shortest Path First (OSPF) is a link-state protocol that uses Dijkstra’s algorithm to compute the shortest path tree. It divides a large network into areas to improve scalability. Unlike RIP, which exchanges periodic updates, OSPF sends updates only when changes occur, reducing overhead. OSPF supports authentication, hierarchical design, and faster convergence, making it suitable for enterprise networks.
58. What is the main purpose of the Border Gateway Protocol (BGP)?
Difficulty: HardType: MCQTopic: routing
- To manage routing within a single organization
- To perform link-state updates inside LANs
- To exchange routing information between autonomous systems on the Internet
- To manage IP address assignments
BGP is an inter-domain routing protocol used to exchange routes between autonomous systems (AS). It helps maintain the global Internet routing table. BGP relies on path vector mechanisms and policies rather than shortest paths, focusing on scalability and policy control.
Correct Answer: To exchange routing information between autonomous systems on the Internet
59. What information does a routing table contain?
Difficulty: EasyType: MCQTopic: routing
- MAC addresses of all connected devices
- User login credentials
- Destination networks, next hops, and metrics
- Application layer service ports
A routing table lists destination IP networks, their next-hop addresses, and the cost or metric to reach them. Routers refer to these tables to forward packets efficiently toward their destination.
Correct Answer: Destination networks, next hops, and metrics
60. What does a default route (0.0.0.0/0) represent in a routing table?
Difficulty: MediumType: MCQTopic: routing
- A route used for local network traffic only
- A backup route for when the router fails
- A route used when no specific route matches a destination address
- A route used only for multicast traffic
The default route serves as a catch-all path for packets that don’t match any specific route in the table. It’s typically used to send traffic toward the Internet through a default gateway.
Correct Answer: A route used when no specific route matches a destination address
61. What are routing loops and how can they be prevented?
Difficulty: HardType: SubjectiveTopic: routing
Routing loops occur when packets circulate endlessly between routers due to incorrect routing information. They waste bandwidth and degrade network performance. Solutions include Split Horizon (preventing routers from advertising routes back on the same interface), Route Poisoning, and Hold-Down timers. Modern link-state protocols avoid loops through consistent network maps and sequence numbers.
62. What is 'Administrative Distance' in routing?
Difficulty: MediumType: MCQTopic: routing
- A physical distance between routers
- A metric representing route reliability across different protocols
- A field in the IP header
- A network congestion indicator
Administrative Distance (AD) defines the trustworthiness of a route learned from a particular protocol. Lower AD values indicate more preferred routes. For example, OSPF has AD 110 while RIP has AD 120, so routers prefer OSPF routes when both exist.
Correct Answer: A metric representing route reliability across different protocols
63. Which of the following is NOT commonly used as a routing metric?
Difficulty: MediumType: MCQTopic: routing
- Hop count
- Bandwidth
- Delay
- MAC address length
Routing metrics quantify route desirability using parameters like hop count, delay, bandwidth, or load. MAC address length is not relevant for routing decisions since it belongs to the Data Link Layer.
Correct Answer: MAC address length
64. What is hierarchical routing and why is it used in large-scale networks?
Difficulty: MediumType: SubjectiveTopic: routing
Hierarchical routing divides a large network into regions or areas, allowing routers to maintain smaller routing tables. Each region summarizes routes before advertising them externally, reducing overhead and improving scalability. OSPF uses this concept by creating backbone and area routers. This design keeps large networks stable and efficient.
65. Explain the concept of network convergence in routing.
Difficulty: MediumType: SubjectiveTopic: routing
Convergence refers to the state when all routers in a network have consistent and updated routing tables. After a topology change, routing protocols exchange updates until they agree on the new paths. Fast convergence is essential for reliability, preventing loops and packet loss. OSPF and EIGRP converge faster than distance-vector protocols like RIP.
66. Which of the following best describes the main role of the Transport Layer?
Difficulty: EasyType: MCQTopic: transport layer
- Provide end-to-end communication and reliability between applications
- Handle logical addressing of packets across networks
- Transmit electrical signals through cables
- Translate domain names into IP addresses
The Transport Layer ensures reliable or best-effort end-to-end delivery between processes on different hosts. It handles segmentation, acknowledgment, flow control, and error recovery, enabling application-level communication over the network.
Correct Answer: Provide end-to-end communication and reliability between applications
67. Which statement correctly compares TCP and UDP?
Difficulty: MediumType: MCQTopic: transport layer
- TCP is connection-oriented; UDP is connectionless
- TCP is faster but unreliable; UDP is slower and reliable
- Both TCP and UDP guarantee ordered delivery
- UDP requires a three-way handshake before data transfer
TCP establishes a connection before data transfer and ensures ordered, reliable delivery. UDP, by contrast, sends datagrams without connection setup, offering lower latency but no guarantee of delivery. Choosing between them depends on the application’s needs.
Correct Answer: TCP is connection-oriented; UDP is connectionless
68. Describe the TCP three-way handshake process.
Difficulty: MediumType: SubjectiveTopic: transport layer
The TCP three-way handshake establishes a reliable connection between client and server. Step 1: The client sends a SYN segment to request connection. Step 2: The server replies with SYN-ACK, acknowledging the request and sending its own SYN. Step 3: The client responds with ACK to confirm. After these three steps both sides are synchronized and can start data transfer. This process ensures both sides are ready and sequence numbers are initialized.
69. Which field in the TCP header ensures that data is delivered in sequence?
Difficulty: MediumType: MCQTopic: transport layer
- Window size
- Sequence number
- Acknowledgment number
- Checksum
The Sequence Number identifies the first byte in the segment’s data, enabling the receiver to reorder out-of-sequence packets correctly. Together with the acknowledgment number, it maintains reliable ordered delivery in TCP.
Correct Answer: Sequence number
70. Explain TCP flow control using the sliding-window mechanism.
Difficulty: MediumType: SubjectiveTopic: transport layer
TCP uses a sliding-window mechanism to manage the amount of data that can be sent before receiving an acknowledgment. The receiver advertises a window size representing how much data it can accept. The sender adjusts its sending rate accordingly, preventing buffer overflow and ensuring efficient use of resources. This dynamic adjustment makes TCP adaptive to varying network conditions.
71. What is the main goal of TCP congestion control?
Difficulty: MediumType: MCQTopic: transport layer
- To prevent packet duplication
- To avoid overwhelming the network with too much traffic
- To increase network delay intentionally
- To reduce data encryption time
Congestion control prevents excessive load on the network that leads to packet loss and reduced throughput. TCP uses algorithms such as slow-start, congestion avoidance, fast retransmit, and fast recovery to adjust the sending rate based on perceived congestion.
Correct Answer: To avoid overwhelming the network with too much traffic
72. During TCP’s slow-start phase, how does the congestion window (cwnd) grow?
Difficulty: MediumType: MCQTopic: transport layer
- Linearly with each acknowledgment
- Exponentially with each round-trip time
- Remains constant until congestion occurs
- Randomly depending on packet loss
In the slow-start phase TCP begins with a small congestion window and doubles it each round-trip time as acknowledgments are received. This rapid increase probes available bandwidth until a threshold is reached, after which growth becomes linear.
Correct Answer: Exponentially with each round-trip time
73. Which feature is true for UDP but not for TCP?
Difficulty: EasyType: MCQTopic: transport layer
- Reliable data transfer
- Connection establishment
- Low latency with no handshake
- Guaranteed delivery
UDP sends data directly without establishing a connection. This reduces delay and overhead, making it ideal for time-sensitive applications like video streaming or gaming. However, reliability and ordering are left to the application.
Correct Answer: Low latency with no handshake
74. What are port numbers and why are they important in transport-layer communication?
Difficulty: EasyType: SubjectiveTopic: application protocols
Port numbers identify specific processes or applications within a host. When data reaches a device, the port number determines which application should handle it. For example, HTTP uses port 80 and HTTPS uses 443. Ports allow multiple network services to run simultaneously on the same machine without conflict.
75. What triggers a retransmission in TCP?
Difficulty: MediumType: MCQTopic: transport layer
- Duplicate acknowledgments or timeout expiration
- Receiver’s buffer being full
- Checksum value being zero
- Congestion window reaching maximum size
TCP retransmits segments when it suspects packet loss—either when a timeout occurs or when three duplicate ACKs are received. The fast retransmit algorithm helps recover quickly from isolated losses without waiting for timeouts.
Correct Answer: Duplicate acknowledgments or timeout expiration
76. Describe how a TCP connection is terminated.
Difficulty: MediumType: SubjectiveTopic: transport layer
TCP uses a four-step termination process. One side sends a FIN to signal it has finished sending. The receiver acknowledges with ACK and may send its own FIN when done. The first side replies with a final ACK. This orderly teardown ensures that all data is delivered and resources are released gracefully. Interviews often ask candidates to contrast this with the three-way handshake.
77. In socket programming, which pair of functions are used to establish a TCP connection?
Difficulty: MediumType: MCQTopic: application protocols
- send() and recv()
- bind() and accept()
- connect() and accept()
- listen() and close()
In TCP socket programming, a client initiates a connection using connect(), while the server waits for requests using accept(). Once connected, data transfer uses send() and recv(). Understanding this flow helps you answer coding-based interview questions.
Correct Answer: connect() and accept()
Example Code
Server: socket(), bind(), listen(), accept()
Client: socket(), connect()
78. Discuss different TCP congestion control variants such as Tahoe, Reno, and New Reno.
Difficulty: HardType: SubjectiveTopic: transport layer
TCP Tahoe introduced slow-start, congestion avoidance, and fast retransmit. When loss is detected, Tahoe resets the congestion window to one segment, causing a full slow-start. TCP Reno added fast recovery, allowing quicker recovery after a single packet loss. TCP New Reno further improved performance by handling multiple losses within one window without waiting for a timeout. Understanding these variants demonstrates knowledge of how TCP evolved to manage congestion efficiently across diverse networks.
79. What is the main responsibility of the Application Layer in the OSI model?
Difficulty: EasyType: MCQTopic: application protocols
- To route packets between networks
- To provide services directly to user applications
- To handle encryption at the transport layer
- To manage switching of physical signals
The Application Layer provides network services directly to end-user applications such as browsers, email clients, or file-transfer tools. It ensures proper communication by offering protocols like HTTP, FTP, and SMTP.
Correct Answer: To provide services directly to user applications
80. Which protocol is primarily used for transferring web pages on the Internet?
Difficulty: MediumType: MCQTopic: application protocols
The Hypertext Transfer Protocol (HTTP) governs how web clients (browsers) and servers exchange data such as HTML documents, images, and scripts. HTTPS is its secure version using SSL/TLS encryption to protect communication.
Correct Answer: HTTP
81. Explain how DNS resolves a domain name to an IP address.
Difficulty: MediumType: SubjectiveTopic: application protocols
The Domain Name System (DNS) translates human-readable domain names into IP addresses. When a user enters a URL, the resolver checks its cache, then queries a root server, a top-level domain server (like .com), and finally an authoritative server for the exact record. The resolved IP address is returned to the client and cached for future use. This hierarchical process ensures fast, scalable name resolution across the Internet.
82. What is the main purpose of the File Transfer Protocol (FTP)?
Difficulty: MediumType: MCQTopic: application protocols
- To send emails
- To transfer files between computers over a network
- To monitor network devices
- To manage encryption keys
FTP allows users to upload and download files from remote servers using separate control and data connections. It supports authentication and directory operations, making it useful for sharing large datasets or website maintenance.
Correct Answer: To transfer files between computers over a network
83. Which protocol is responsible for sending outgoing emails?
Difficulty: MediumType: MCQTopic: application protocols
Simple Mail Transfer Protocol (SMTP) handles sending of emails from clients to mail servers and between servers. POP3 and IMAP are used for retrieving emails. Interviewers often test your ability to distinguish these roles.
Correct Answer: SMTP
84. Differentiate between IMAP and POP3 email retrieval protocols.
Difficulty: MediumType: SubjectiveTopic: application protocols
POP3 downloads messages from the server and usually deletes them after download, allowing offline access but poor synchronization. IMAP keeps emails on the server, enabling access from multiple devices and real-time sync of folders. For modern multi-device email, IMAP is preferred. Mentioning their default ports (POP3 110, IMAP 143, with secure versions 995 and 993) adds detail for interviews.
85. What is the main function of DHCP?
Difficulty: MediumType: MCQTopic: application protocols
- To resolve domain names to IP addresses
- To dynamically assign IP addresses and configuration parameters to hosts
- To route data packets between networks
- To manage transport-layer connections
Dynamic Host Configuration Protocol (DHCP) automates IP assignment, reducing manual configuration. It provides IP, subnet mask, gateway, and DNS information during device startup. The process involves four steps: Discover, Offer, Request, and Acknowledge.
Correct Answer: To dynamically assign IP addresses and configuration parameters to hosts
86. Which protocol is used for managing and monitoring network devices?
Difficulty: MediumType: MCQTopic: application protocols
Simple Network Management Protocol (SNMP) enables administrators to monitor device status, performance, and configuration using management information bases (MIBs). It’s critical in enterprise network maintenance and troubleshooting.
Correct Answer: SNMP
87. How does HTTPS secure data transfer compared to HTTP?
Difficulty: MediumType: SubjectiveTopic: application protocols
HTTPS adds a security layer using SSL/TLS encryption. Before communication, the client and server perform a handshake to establish encryption keys and verify certificates. This ensures confidentiality, integrity, and authenticity. Even if packets are intercepted, the encrypted data remains unreadable. Emphasizing this distinction highlights awareness of secure web communication practices.
88. Which HTTP methods are commonly used in RESTful APIs?
Difficulty: MediumType: MCQTopic: application protocols
- GET, POST, PUT, DELETE
- SEND, RECEIVE, CONNECT, DROP
- OPEN, CLOSE, READ, WRITE
- INIT, SYNC, ACK, END
RESTful APIs follow HTTP standards where GET retrieves data, POST creates, PUT updates, and DELETE removes resources. Understanding these verbs and their stateless behavior is a frequent modern interview topic.
Correct Answer: GET, POST, PUT, DELETE
89. Explain what a proxy server does in a network.
Difficulty: MediumType: SubjectiveTopic: application protocols
A proxy server acts as an intermediary between client and server. It forwards client requests, caches frequently accessed data, hides client identities, and filters content. Proxies improve performance and add security by isolating internal networks from external traffic. Companies often use them for logging and access control.
90. In HTTP, what is the role of cookies?
Difficulty: EasyType: MCQTopic: application protocols
- To compress web data
- To maintain session information between client and server
- To encrypt files on the disk
- To block advertisements
Cookies store small pieces of data like session IDs on the client side to maintain state in the otherwise stateless HTTP protocol. They help websites remember users, preferences, or login sessions across multiple requests.
Correct Answer: To maintain session information between client and server
91. What is a Content Delivery Network (CDN) and how does it improve web performance?
Difficulty: HardType: SubjectiveTopic: application protocols
A CDN is a globally distributed network of servers that cache and deliver web content from the nearest geographical location to the user. This reduces latency, balances load, and enhances availability. When a user requests data, the CDN directs them to the closest edge server, minimizing delay and bandwidth costs. Mentioning popular CDNs like Cloudflare or Akamai shows practical awareness.
92. What is the main goal of network security?
Difficulty: EasyType: MCQTopic: network security
- To speed up data transmission
- To ensure confidentiality, integrity, and availability of data
- To reduce network size
- To convert analog data into digital form
Network security focuses on protecting data as it travels through a network. It ensures confidentiality (preventing unauthorized access), integrity (preventing unauthorized modification), and availability (ensuring access when needed). These three principles form the CIA triad — the foundation of cybersecurity.
Correct Answer: To ensure confidentiality, integrity, and availability of data
93. What is encryption?
Difficulty: MediumType: MCQTopic: network security
- Compressing data for storage
- Transforming readable data into unreadable format using algorithms and keys
- Deleting old data permanently
- Encoding files into binary format
Encryption is the process of converting plaintext into ciphertext to protect it from unauthorized access. Only authorized users with the correct key can decrypt and read the data. It is essential for secure communication across untrusted networks like the Internet.
Correct Answer: Transforming readable data into unreadable format using algorithms and keys
94. Explain the difference between symmetric and asymmetric encryption with examples.
Difficulty: MediumType: SubjectiveTopic: network security
Symmetric encryption uses the same key for both encryption and decryption, making it fast and efficient. Examples include AES and DES. However, key distribution is a challenge because both parties must securely share the same key. Asymmetric encryption uses a public key for encryption and a private key for decryption. It is slower but solves the key distribution problem. RSA and ECC are common examples. In practice, systems combine both—using asymmetric encryption to exchange symmetric session keys.
95. What is the function of a firewall?
Difficulty: MediumType: MCQTopic: network security
- To detect viruses on end-user devices
- To block or permit network traffic based on security rules
- To convert analog signals to digital
- To manage IP addressing
A firewall monitors and controls incoming and outgoing network traffic using predefined security rules. It acts as a barrier between trusted and untrusted networks, protecting against unauthorized access and attacks. Firewalls can be hardware, software, or both.
Correct Answer: To block or permit network traffic based on security rules
96. Which protocol secures web communication by encrypting data between browser and server?
Difficulty: MediumType: MCQTopic: network security
Secure Sockets Layer (SSL) and Transport Layer Security (TLS) provide end-to-end encryption for web traffic. They ensure that data exchanged between a web browser and server remains confidential and tamper-proof. Modern browsers use TLS, the successor to SSL.
Correct Answer: SSL/TLS
97. What is a Virtual Private Network (VPN), and how does it secure data?
Difficulty: MediumType: SubjectiveTopic: network security
A VPN creates an encrypted tunnel between the user’s device and a remote server over the public Internet. It masks the user’s IP address and secures data from eavesdroppers. VPNs are widely used for remote work, secure browsing, and bypassing geo-restrictions. In interviews, explain how VPNs use encryption and tunneling protocols like IPSec or OpenVPN to provide confidentiality and integrity.
98. What is the main purpose of hashing in network security?
Difficulty: MediumType: MCQTopic: network security
- To encrypt and decrypt data
- To verify data integrity using fixed-size hash values
- To compress large files for transfer
- To manage user sessions
Hashing converts data into a fixed-length digest using algorithms like SHA or MD5. It is used to detect unauthorized modifications. Even small changes in input produce a different hash, making it ideal for verifying file integrity or storing passwords securely.
Correct Answer: To verify data integrity using fixed-size hash values
99. What is the main difference between an Intrusion Detection System (IDS) and an Intrusion Prevention System (IPS)?
Difficulty: MediumType: MCQTopic: network security
- IDS monitors network traffic; IPS actively blocks malicious traffic
- IDS encrypts traffic; IPS decrypts traffic
- IDS handles email filtering; IPS manages routing
- They perform the same function
An IDS detects and alerts administrators about suspicious activities, while an IPS goes a step further by automatically taking action to block or prevent attacks. Both systems are essential for layered network defense.
Correct Answer: IDS monitors network traffic; IPS actively blocks malicious traffic
100. What is a Denial-of-Service (DoS) attack and how can networks defend against it?
Difficulty: MediumType: SubjectiveTopic: network security
A DoS attack overwhelms a target system with excessive traffic, making it unavailable to legitimate users. Distributed DoS (DDoS) attacks amplify this by using multiple compromised systems. Defense strategies include rate limiting, firewalls, load balancing, and using anti-DDoS services. In interviews, discuss both preventive measures and detection tools like intrusion detection systems or content delivery networks.
101. What is the role of a Certificate Authority (CA) in Public Key Infrastructure (PKI)?
Difficulty: HardType: MCQTopic: network security
- To generate random encryption keys
- To validate and issue digital certificates
- To manage routing protocols
- To handle DNS resolution
A Certificate Authority (CA) verifies the identity of entities (users, websites, or organizations) and issues digital certificates to prove their authenticity. PKI relies on trusted CAs to ensure secure communication across networks like HTTPS.
Correct Answer: To validate and issue digital certificates
102. What does IPSec provide in network communication?
Difficulty: MediumType: MCQTopic: network security
- Only encryption
- Only authentication
- Encryption, authentication, and integrity at the network layer
- Routing between networks
IPSec secures IP communication by authenticating and encrypting each IP packet in a communication session. It operates at the network layer and supports VPNs, ensuring confidentiality, data integrity, and origin authentication.
Correct Answer: Encryption, authentication, and integrity at the network layer
103. Explain a Man-in-the-Middle (MITM) attack and how encryption helps prevent it.
Difficulty: HardType: SubjectiveTopic: network security
In a MITM attack, an attacker secretly intercepts and alters communication between two parties without their knowledge. They can steal credentials or inject malicious data. Encryption protocols like SSL/TLS prevent this by ensuring both parties exchange data securely with verified identities. Always mention mutual authentication and certificate validation as key defenses during interviews.
104. What are network security policies, and why are they important?
Difficulty: MediumType: SubjectiveTopic: network security
Network security policies define the rules and procedures for protecting organizational assets. They include password policies, access control lists, data handling guidelines, and incident response procedures. These policies ensure consistent security behavior and compliance with standards like ISO 27001 or GDPR. Interviewers appreciate when you connect policies to practical enforcement mechanisms like firewalls and monitoring systems.
105. Which of the following is a key characteristic of wireless networks?
Difficulty: EasyType: MCQTopic: wireless & mobile networks
- They use physical cables for communication
- They transmit data using radio waves or infrared signals
- They can only connect two devices directly
- They are limited to local connections only
Wireless networks use electromagnetic waves to transmit data through the air, removing the need for cables. This allows mobility, flexibility, and ease of setup in environments where wiring is difficult or costly.
Correct Answer: They transmit data using radio waves or infrared signals
106. Which IEEE standard defines Wi-Fi?
Difficulty: MediumType: MCQTopic: wireless & mobile networks
- IEEE 802.3
- IEEE 802.5
- IEEE 802.11
- IEEE 802.15
IEEE 802.11 defines wireless LAN (Wi-Fi) standards. It specifies how devices communicate wirelessly using radio waves in the 2.4 GHz or 5 GHz bands. Variants like 802.11n, 802.11ac, and 802.11ax improve speed and range.
Correct Answer: IEEE 802.11
107. What is the role of an access point in a wireless network?
Difficulty: MediumType: MCQTopic: network devices
- It connects wired networks to the Internet
- It acts as a central hub that connects wireless devices to a wired network
- It encrypts all transmitted data
- It detects interference from nearby devices
An access point connects wireless clients to a wired network infrastructure. It allows mobile users to connect and move within the network’s range. Access points form the backbone of wireless LAN architecture.
Correct Answer: It acts as a central hub that connects wireless devices to a wired network
108. Explain the concept of a cellular network and its structure.
Difficulty: MediumType: SubjectiveTopic: wireless & mobile networks
A cellular network divides geographic areas into small regions called cells, each served by a base station. Mobile devices communicate with the nearest base station, which connects to a switching center for call routing or Internet access. As users move between cells, handover mechanisms maintain uninterrupted connectivity. This design allows efficient frequency reuse and broad coverage.
109. What is the main benefit of frequency reuse in cellular systems?
Difficulty: MediumType: MCQTopic: physical layer & transmission
- It avoids signal interference completely
- It increases data encryption strength
- It allows multiple cells to use the same frequencies without interference
- It eliminates the need for base stations
Frequency reuse allows non-adjacent cells to operate on the same frequency bands, maximizing spectrum efficiency. Proper planning ensures signals from reused frequencies do not interfere with each other.
Correct Answer: It allows multiple cells to use the same frequencies without interference
110. What is handover (handoff) in mobile networks, and why is it important?
Difficulty: MediumType: SubjectiveTopic: wireless & mobile networks
Handover is the process where an ongoing call or data session is transferred from one cell’s base station to another as the user moves. It ensures seamless connectivity without drops. There are two main types: hard handover (break before make) and soft handover (make before break). Smooth handovers are crucial for uninterrupted mobile communication, especially in fast-moving environments like vehicles.
111. Which IEEE standard defines Bluetooth technology?
Difficulty: EasyType: MCQTopic: wireless & mobile networks
- 802.11
- 802.3
- 802.15.1
- 802.16
Bluetooth is based on the IEEE 802.15.1 standard. It supports short-range communication using low-power radio waves, typically for personal area networks connecting devices like phones, headsets, and keyboards.
Correct Answer: 802.15.1
112. What defines an ad hoc wireless network?
Difficulty: MediumType: MCQTopic: wireless & mobile networks
- It requires a central access point
- It dynamically forms between devices without fixed infrastructure
- It operates only in cellular environments
- It uses fiber optic cables
An ad hoc network is self-organizing, where devices connect directly to each other to exchange data without relying on routers or access points. It’s useful in temporary or emergency setups like disaster recovery operations.
Correct Answer: It dynamically forms between devices without fixed infrastructure
113. Explain how Mobile IP allows a device to maintain connectivity while moving between networks.
Difficulty: MediumType: SubjectiveTopic: wireless & mobile networks
Mobile IP allows devices to keep a consistent IP address even when they move between networks. It does this through a home agent that forwards packets to the device’s current location via a care-of address. This ensures uninterrupted sessions for mobile users without needing to reconfigure IP settings.
114. Which wireless security protocol is considered the most secure today?
Difficulty: MediumType: MCQTopic: wireless & mobile networks
WPA3 is the most recent and secure Wi-Fi security protocol. It replaces the outdated WEP and improves on WPA2 by offering stronger encryption, forward secrecy, and protection against brute-force attacks.
Correct Answer: WPA3
115. Describe how satellite communication works and list its advantages and disadvantages.
Difficulty: HardType: SubjectiveTopic: physical layer & transmission
Satellite communication uses orbiting satellites as relay stations to transmit signals between distant locations. Uplink sends data to the satellite, which retransmits it down to ground stations (downlink). Advantages include global coverage and quick deployment. However, it faces issues like high latency, signal loss during weather changes, and expensive equipment. Still, it’s crucial for remote regions and broadcasting.
116. Which of the following is a key feature of 5G technology?
Difficulty: MediumType: MCQTopic: wireless & mobile networks
- Only voice-based communication
- High latency with low bandwidth
- Ultra-low latency and high data rates
- Dependence solely on 3G infrastructure
5G networks offer ultra-low latency (around 1 ms), high throughput, and support for massive device connectivity. It enables advanced applications like IoT, autonomous vehicles, and real-time cloud gaming.
Correct Answer: Ultra-low latency and high data rates
117. Compare Wi-Fi and cellular networks in terms of coverage, speed, and cost.
Difficulty: MediumType: SubjectiveTopic: wireless & mobile networks
Wi-Fi networks offer high-speed connectivity in limited areas like homes or offices, often at lower cost since they use local broadband connections. Cellular networks provide broader coverage through telecom infrastructure and support mobility but may have higher costs and usage limits. In interviews, emphasize how modern devices seamlessly switch between both for optimal connectivity.
118. What is the key idea behind Software-Defined Networking (SDN)?
Difficulty: MediumType: MCQTopic: modern networking
- Combining data and control planes in each device
- Separating control and data planes for centralized network management
- Replacing routers with switches
- Encrypting all data packets by default
SDN separates the network’s control logic (brains) from the forwarding hardware (data plane). A central controller dynamically manages traffic flow across the entire network. This flexibility makes SDN ideal for cloud environments and automated configuration.
Correct Answer: Separating control and data planes for centralized network management
119. Explain what network automation is and how it benefits organizations.
Difficulty: MediumType: SubjectiveTopic: modern networking
Network automation uses scripts, APIs, or tools to automatically configure, manage, and test network devices. It reduces manual errors, speeds up deployment, and ensures consistency. Tools like Ansible, Puppet, and Cisco DNA Center help automate routine tasks like VLAN setup or policy updates. In interviews, link automation with cost savings and agility in managing large infrastructures.
120. Which protocol is widely used for IoT communication due to its lightweight design?
Difficulty: MediumType: MCQTopic: wireless & mobile networks
MQTT (Message Queuing Telemetry Transport) is a lightweight publish-subscribe protocol designed for constrained IoT devices and low-bandwidth networks. It ensures reliable communication between sensors and cloud services with minimal power use.
Correct Answer: MQTT
121. What is the goal of network virtualization?
Difficulty: MediumType: MCQTopic: modern networking
- To reduce the number of network protocols used
- To combine multiple physical networks into one logical network
- To allow multiple logical networks to share the same physical infrastructure
- To eliminate routers entirely
Network virtualization abstracts physical networking resources into logical networks. This allows flexible creation of isolated environments for different tenants or applications without changing hardware, improving scalability and utilization.
Correct Answer: To allow multiple logical networks to share the same physical infrastructure
122. Which service model focuses on providing virtualized network functions over the Internet?
Difficulty: MediumType: MCQTopic: modern networking
Network as a Service (NaaS) delivers network services such as routing, VPNs, and firewalls on demand via the cloud. It allows organizations to scale and manage networks through APIs without investing in physical infrastructure.
Correct Answer: NaaS
123. Describe a structured approach to troubleshooting network issues.
Difficulty: MediumType: SubjectiveTopic: operations & troubleshooting
A good troubleshooting approach starts by identifying the problem, gathering information, and isolating the cause layer by layer (using the OSI model). Tools like ping, traceroute, and netstat help test connectivity and routing. Once identified, apply fixes, verify the result, and document the solution. Interviewers value clear, logical methods showing you can diagnose real-world network failures.
124. What does the ping command test?
Difficulty: EasyType: MCQTopic: operations & troubleshooting
- Bandwidth utilization
- Round-trip time and connectivity between hosts
- Firewall rule configuration
- DNS zone transfers
Ping sends ICMP echo requests to check if a host is reachable and measures round-trip time. It’s one of the simplest yet most useful troubleshooting tools to verify basic connectivity.
Correct Answer: Round-trip time and connectivity between hosts
Example Code
ping google.com
125. How does the traceroute command help diagnose network problems?
Difficulty: MediumType: MCQTopic: operations & troubleshooting
- It measures download speed
- It shows each hop a packet takes to reach its destination
- It encrypts traffic before sending
- It clears network caches
Traceroute helps visualize the path a packet takes through intermediate routers. It uses TTL values to reveal each hop and detect where delays or failures occur. This is invaluable for identifying routing issues or bottlenecks.
Correct Answer: It shows each hop a packet takes to reach its destination
Example Code
traceroute 8.8.8.8
126. What does a low signal-to-noise ratio (SNR) indicate in a network?
Difficulty: MediumType: MCQTopic: physical layer & transmission
- Stronger signal quality
- Weak signal or high interference
- Stable connection
- Low bandwidth usage
A low SNR means the useful signal is nearly drowned out by background noise, causing packet loss or poor performance. Improving cabling, reducing interference, or boosting signal power can enhance reliability.
Correct Answer: Weak signal or high interference
127. How do network logs assist in diagnosing and preventing network issues?
Difficulty: MediumType: SubjectiveTopic: operations & troubleshooting
Network logs record connection attempts, device activity, and errors. Reviewing logs helps trace security incidents, detect misconfigurations, and identify trends before problems escalate. Centralized logging tools like Splunk or ELK make it easier to correlate events across devices. Interviews often test your ability to use logs for root-cause analysis.
128. Which of the following is a commonly used network monitoring tool?
Difficulty: MediumType: MCQTopic: operations & troubleshooting
- Wireshark
- Photoshop
- AutoCAD
- IntelliJ IDEA
Wireshark captures and analyzes network packets in real time. It helps diagnose latency, protocol errors, and security issues. Network engineers use it to visually inspect traffic and troubleshoot complex issues.
Correct Answer: Wireshark
129. What is the main advantage of SD-WAN (Software-Defined Wide Area Network)?
Difficulty: MediumType: MCQTopic: modern networking
- It eliminates all need for routing protocols
- It enables centralized control and optimizes WAN performance over multiple links
- It replaces VPNs with wireless access points
- It works only on private leased lines
SD-WAN uses software intelligence to dynamically route traffic over the best available path (MPLS, broadband, or LTE). It enhances performance, reduces cost, and simplifies network management across distributed sites.
Correct Answer: It enables centralized control and optimizes WAN performance over multiple links
130. Discuss future trends in networking such as AI-driven management and intent-based networking.
Difficulty: HardType: SubjectiveTopic: modern networking
Future networks will be self-optimizing, using AI and machine learning to predict failures, balance loads, and enforce intent-based policies. Intent-based networking lets administrators describe 'what' the network should do, while automation handles 'how' it’s done. These trends reduce human error, enhance security, and enable adaptive networks ideal for cloud and IoT ecosystems.