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Computer Network Notes (Panjab
University)
1. What is a Computer Network?
Answer: A computer network is a collection of interconnected devices (such as computers, servers, and network devices) that can communicate with each other to share resources like data, files, and hardware devices. Networks can be classified into various types, including Local Area Networks (LAN), Wide Area Networks (WAN), and Metropolitan Area Networks (MAN), based on their size and scope.
2. What are the types of Computer Networks?
Answer: Computer networks can be classified into several types:
LAN (Local Area Network): A network that is confined to a small geographical area, like a home, office, or building.
WAN (Wide Area Network): A network that spans a large geographical area, often connecting cities or countries.
MAN (Metropolitan Area Network): A network that covers a larger area than LAN but smaller than WAN, usually within a city or large campus.
PAN (Personal Area Network): A network used for personal devices, typically within a range of 10 meters.
CAN (Campus Area Network): A network used within a campus like a university or corporate campus.
3. What is OSI Model?
Answer: The OSI (Open Systems Interconnection) model is a conceptual framework used to understand and describe how different networking protocols work together in a communication system. It divides network communication into seven layers:
- Physical Layer: Deals with hardware transmission, including cables, switches, and other physical devices.
- Data Link Layer: Ensures reliable data transfer between devices on the same network by handling error detection and correction.
- Network Layer: Manages the routing and forwarding of data packets, and handles logical addressing (IP addresses).
- Transport Layer: Ensures reliable data transfer between two devices, handles error recovery, and flow control.
- Session Layer: Manages sessions or connections between devices.
- Presentation Layer: Translates data between the application and transport layers, including encryption and compression.
- Application Layer: Provides network services to end-users, such as email, file transfer, and web browsing.
4. What is the difference between TCP and UDP?
Answer:
TCP (Transmission Control Protocol): TCP is a connection-oriented protocol that guarantees reliable data delivery. It ensures that data is received in order and without errors, which is useful for applications that require reliability, such as web browsing and email.
Answer: Transmission media refer to the physical pathways that data travels through in a network. The main types include:
Wired Media:
Twisted Pair Cable: Commonly used in LANs, consisting of pairs of wires twisted together.
Coaxial Cable: Used for cable television and broadband internet connections.
Fiber Optic Cable: Uses light signals to transmit data at high speeds over long distances.
Wireless Media:
Radio Waves: Used for Wi-Fi, mobile networks, and Bluetooth.
Microwaves: Used for point-to-point communication.
Infrared: Used for short-range communication, such as remote controls.
9. What is a Router?
Answer: A router is a device that connects different networks and forwards data packets between them. It determines the optimal path for data to travel based on IP addresses and routing protocols. Routers are commonly used to connect local networks to the internet.
10. What is a Switch in a Computer Network?
Answer: A switch is a network device that operates at the Data Link Layer and is responsible for forwarding data frames between devices within the same network. Unlike hubs, which broadcast data to all connected devices, switches only send data to the device that requires it, improving efficiency and reducing network traffic.
11. What is Network Security?
Answer: Network security refers to the protection of a computer network from unauthorized access, misuse, and attacks. It includes measures like firewalls, encryption, intrusion detection systems (IDS), and secure protocols (e.g., HTTPS) to safeguard data and prevent cyber threats.
12. What are the different types of network topologies?
Answer: Network topology refers to the arrangement of devices in a network. Common topologies include:
Bus Topology: All devices are connected to a single central cable (the bus).
Star Topology: Devices are connected to a central hub or switch.
Ring Topology: Devices are connected in a closed loop, and data circulates in one direction.
Mesh Topology: Every device is connected to every other device in the network.
Tree Topology: A hybrid topology that combines characteristics of bus and star topologies.
