JNTUK B.Tech CSE 3-1 (R23) Computer Networks 2 Marks Important Questions & Answers (Unit-Wise) for all 5 units are available. By preparing these questions you can get good marks in your semester end examinations.
UNIT I: Introduction & Physical Layer
1. What is a Computer Network?
Answer: A computer network is a collection of interconnected devices (nodes) that communicate and share resources using communication links.
2. List the types of networks.
Answer: The main types are:
- LAN (Local Area Network)
- MAN (Metropolitan Area Network)
- WAN (Wide Area Network)
3. What is a LAN?
Answer: A LAN is a network that connects computers within a small geographic area (like a building or campus) using high-speed communication links.
4. List different network topologies.
Answer: Bus, Star, Ring, Mesh, Tree, and Hybrid topologies.
5. What is the OSI Reference Model?
Answer: The OSI (Open Systems Interconnection) model is a seven-layer conceptual framework that standardizes network communication functions.
6. What are the layers of TCP/IP model?
- Application
- Transport
- Internet
- Network Access (Link) layer
7. What is the main difference between OSI and TCP/IP models?
Answer: OSI has seven layers, TCP/IP has four layers; OSI is a theoretical model, whereas TCP/IP is practical and protocol-based.
8. What are guided transmission media?
Answer: Guided media include Twisted Pair Cable, Coaxial Cable, and Fiber Optic Cable, where signals travel through a physical path.
UNIT II: Data Link Layer
1. What are the design issues of the data link layer?
- Framing
- Flow Control
- Error Control
- Providing services to the network layer
2. What is framing?
Answer: Framing divides the bit stream into discrete units called frames, allowing the receiver to detect frame boundaries.
3. What is flow control?
Answer: Flow control ensures that a fast sender does not overwhelm a slow receiver by regulating the amount of data sent.
4. What is error control?
Answer: Error control detects and corrects errors that occur during transmission using redundancy bits and retransmission.
5. What is CRC?
Answer: Cyclic Redundancy Check (CRC) is an error-detection technique based on binary division of data by a generator polynomial.
6. What is Checksum?
Answer: Checksum is an error detection method where data is divided into segments, summed, and the complement of the sum is transmitted.
7. What is Stop-and-Wait protocol?
Answer: It is a simple flow control protocol where the sender sends one frame and waits for its acknowledgment before sending the next.
8. What is the difference between Go-Back-N and Selective Repeat protocols?
- Go-Back-N: Resends all frames after an error.
- Selective Repeat: Resends only the erroneous frames, improving efficiency.
UNIT III: Media Access Control (MAC) & Wired LANs
1. What is MAC?
Answer: Media Access Control determines how multiple devices share a common communication medium efficiently.
2. What is ALOHA?
Answer: ALOHA is a random access protocol where users transmit whenever they have data; collisions are handled by retransmission after a random time.
3. What is CSMA?
Answer: Carrier Sense Multiple Access allows a device to sense the channel before transmitting to avoid collisions.
4. What is CSMA/CD?
Answer: Carrier Sense Multiple Access with Collision Detection detects collisions during transmission and aborts, then retries after a back-off time.
5. What is CSMA/CA?
Answer: Carrier Sense Multiple Access with Collision Avoidance reduces collisions by using acknowledgment and reservation mechanisms, mainly in wireless networks.
6. What are controlled access protocols?
Answer: Reservation, Polling, and Token Passing are controlled access methods that coordinate transmission to avoid collisions.
7. What is Ethernet?
Answer: Ethernet is a widely used LAN technology based on the CSMA/CD protocol, providing speeds from 10 Mbps to 10 Gbps.
8. Differentiate between Fast Ethernet and Gigabit Ethernet.
- Fast Ethernet: 100 Mbps, backward compatible with 10 Mbps.
- Gigabit Ethernet: 1 Gbps or more, uses full-duplex, supports higher bandwidth applications.
UNIT IV: Network Layer
1. What is the main function of the network layer?
Answer: The network layer is responsible for packet forwarding, routing, addressing, and providing services to the transport layer.
2. What is packet switching?
Answer: Packet switching breaks data into packets that are transmitted independently through the network and reassembled at the destination.
3. What is store-and-forward switching?
Answer: Each packet is received completely at an intermediate node, stored temporarily, and then forwarded to the next node.
4. What is a datagram network?
Answer: A connectionless network where each packet is treated independently and may follow different paths to the destination.
5. What is a virtual-circuit network?
Answer: A connection-oriented network where a logical path is established before data transfer; all packets follow this fixed route.
6. List services provided by the network layer to the transport layer.
- Connectionless service (datagram)
- Connection-oriented service (virtual circuit)
7. Differentiate between connection-oriented and connectionless services.
- Connection-oriented: Reliable, fixed path, setup required.
- Connectionless: No setup, independent packets, may take different paths.
8. Compare virtual-circuit and datagram networks.
- Virtual-circuit: Predefined path, setup required, reliable.
- Datagram: No setup, flexible routing, less overhead.
UNIT – V: Transport Layer & Application Layer
1. What is the main function of the Transport Layer?
Answer: The transport layer provides process-to-process delivery of data, ensuring reliable, transparent data transfer between end systems.
2. List the services provided by the Transport Layer.
- Connection-oriented and connectionless transport
- Reliable data transfer
- Error control
- Flow control
- Multiplexing and demultiplexing
3. What is multiplexing in the transport layer?
Answer: Multiplexing allows multiple application processes to share the same transport layer protocol and network connection simultaneously.
4. Differentiate between connection-oriented and connectionless transport services.
- Connection-oriented: A connection is established before data transfer (e.g., TCP).
- Connectionless: No prior connection; data is sent as independent packets (e.g., UDP).
5. What is the difference between TCP and UDP?
- TCP: Reliable, connection-oriented, error control, flow control.
- UDP: Unreliable, connectionless, faster, no error or flow control.
6. What is flow control in the transport layer?
Answer: Flow control ensures that the sender does not overwhelm the receiver by adjusting the data transmission rate.
7. What is congestion control?
Answer: Congestion control prevents excessive data load in the network, ensuring smooth data flow and avoiding network collapse.
8. What are some common Application Layer protocols?
- HTTP – HyperText Transfer Protocol
- FTP – File Transfer Protocol
- SMTP – Simple Mail Transfer Protocol
- DNS – Domain Name System
- TELNET / SSH – Remote login protocols