Computer Networks-I Exam Paper 2

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Here are the answers to the given questions in simple terms:

a) Which is a connection-oriented transport layer protocol?

  • TCP (Transmission Control Protocol) is a connection-oriented transport layer protocol that ensures reliable data transfer between devices.

b) Identify the class of the IP addresses 192.168.60.12 and 10.11.1.1

  • 192.168.60.12 → Class C (Range: 192.0.0.0 to 223.255.255.255)
  • 10.11.1.1 → Class A (Range: 1.0.0.0 to 126.255.255.255)

c) Define congestion.

  • Congestion occurs when too much data is sent over a network, causing slow speeds, packet loss, or delays.

d) What is fragmentation?

  • Fragmentation is the process of breaking large data packets into smaller pieces so they can be transmitted over networks that have size limits.

e) Convert dotted decimal IP address to binary address: 255.255.0.0

  • 255.255.0.0 in binary is → 11111111.11111111.00000000.00000000

f) What is socket address?

  • A socket address is a combination of an IP address and a port number, which uniquely identifies a device and a specific service on that device. For example, 192.168.1.1:8080.

g) How many maximum number of computers are used to create a piconet?

  • A piconet (in Bluetooth technology) can have a maximum of 8 devices—1 master and 7 slave devices.

h) Apply bit stuffing on the pattern: 01001111111101111110

  • In bit stuffing, after five consecutive 1s, a 0 is added to avoid confusion with control signals.
  • Original: 01001111111101111110
  • Stuffed: 010011111011110111110

i) What is Ethernet?

  • Ethernet is a widely used technology for connecting devices in a Local Area Network (LAN), enabling them to communicate and share data.

j) What is a network?

  • A network is a group of interconnected devices (like computers, printers, etc.) that can communicate and share resources such as files and internet access.

Q2) Attempt any FOUR of the following (out of FIVE): [4×2=8]

a) List different tasks performed by the network layer.

The Network Layer is responsible for delivering data packets from the source to the destination across multiple networks. Key tasks include:

  1. Routing: Determines the best path for data to travel across networks.
  2. Logical Addressing: Assigns unique IP addresses to devices for identification.
  3. Packet Forwarding: Transfers packets from one network to another using routers.
  4. Fragmentation and Reassembly: Breaks large packets into smaller ones for transmission and reassembles them at the destination.
  5. Error Handling: Manages errors in packet delivery.

b) What are the three phases of Mobile IP?

Mobile IP allows devices to move across different networks while maintaining the same IP address. The three phases are:

  1. Agent Discovery: The mobile device identifies nearby foreign and home agents to know its current network location.
  2. Registration: The mobile device registers with a foreign agent to inform its home agent about its current location.
  3. Tunneling: The home agent forwards data to the mobile device via the foreign agent using a tunneling process.

c) List classes for classful IP addressing.

Classful IP addressing divides IP addresses into five classes:

  1. Class A:
    • Range: 1.0.0.0 to 126.255.255.255
    • Used for large networks.
  2. Class B:
    • Range: 128.0.0.0 to 191.255.255.255
    • Used for medium-sized networks.
  3. Class C:
    • Range: 192.0.0.0 to 223.255.255.255
    • Used for small networks.
  4. Class D:
    • Range: 224.0.0.0 to 239.255.255.255
    • Reserved for multicast groups.
  5. Class E:
    • Range: 240.0.0.0 to 255.255.255.255
    • Reserved for experimental purposes.

d) What are the functions of the transport layer?

The Transport Layer ensures reliable and efficient data transfer between devices. Its main functions are:

  1. Connection Establishment and Termination: Sets up and ends communication between devices.
  2. Reliable Data Transfer: Ensures data is delivered without errors, in the correct order.
  3. Flow Control: Prevents data overflow by managing the rate of data transmission.
  4. Error Control: Detects and retransmits lost or corrupted data.
  5. Multiplexing: Allows multiple applications to use the network simultaneously by assigning unique port numbers.

e) What is TCP?

TCP (Transmission Control Protocol) is a connection-oriented transport layer protocol that ensures reliable and ordered delivery of data between devices.

Key Features of TCP:

  • Connection-Oriented: Establishes a connection before data transfer.
  • Reliable: Guarantees delivery and retransmits lost data if needed.
  • Ordered Data Transfer: Ensures that data arrives in the correct order.
  • Error Checking: Uses checksums to detect and correct errors.
  • Flow Control: Prevents data overflow by controlling the data flow rate.

These answers explain the concepts clearly and concisely.

Here are the detailed solutions for all the provided questions in a simple and clear manner:

Q3) Attempt any TWO of the following (Out of THREE): [2 × 4 = 8]

a) What are the types of CSMA Protocols?

The types of CSMA (Carrier Sense Multiple Access) protocols are:

  1. 1. CSMA (Basic):
    • Devices sense the medium and transmit if it’s idle.
  2. 2. CSMA/CD (Collision Detection):
    • Used in wired networks (like Ethernet). Devices detect collisions and resend data after a random time.
  3. 3. CSMA/CA (Collision Avoidance):
    • Used in wireless networks (like Wi-Fi). It avoids collisions by waiting for a random time before transmitting.
  4. 4. CSMA with RTS/CTS (Request to Send / Clear to Send):
    • Reduces collisions by sending an RTS signal first. If the channel is free, the receiver replies with CTS.

b) Write the advantages of computer networks.

Some major advantages of computer networks are:

  1. Resource Sharing: Devices like printers, storage, and internet connections can be shared.
  2. Communication: Enables easy communication through emails, chats, and video conferencing.
  3. Data Sharing: Allows fast and easy file sharing between devices.
  4. Centralized Data Management: Easier to manage and backup data centrally.
  5. Remote Access: Users can access systems and data remotely.
  6. Cost-Efficient: Reduces hardware and software costs by sharing resources.

c) Explain the distinct steps involved in circuit switching.

Circuit switching involves three main steps:

  1. Circuit Establishment:
    • A dedicated communication path is established between the sender and receiver.
  2. Data Transfer:
    • Data is transmitted through the established path without interruption.
  3. Circuit Termination:
    • After the data transfer is complete, the connection is terminated, and resources are released.

Q4) Attempt any TWO of the following (Out of THREE): [2 × 4 = 8]

a) Write the policies adopted by open loop congestion control.

Open loop congestion control prevents congestion before it happens using the following policies:

  1. Traffic Shaping: Controls the amount and rate of traffic sent into the network.
  2. Admission Control: Limits entry of data into the network based on its capacity.
  3. Resource Allocation: Allocates network resources properly to avoid congestion.
  4. Packet Scheduling: Determines the order in which packets are transmitted to avoid delays.

b) Explain IPv6 Address Types.

IPv6 defines the following types of addresses:

  1. Unicast:
    • Identifies a single unique interface. Data is sent to only one destination.
  2. Multicast:
    • Identifies a group of devices. Data is sent to all devices in that group.
  3. Anycast:
    • Assigned to multiple devices, but data is delivered to the nearest device based on routing distance.

c) Which services are provided by TCP?

TCP provides several key services:

  1. Reliable Data Transfer: Ensures data is delivered without errors and in order.
  2. Connection-Oriented Service: Establishes a connection before transferring data.
  3. Error Checking: Uses checksums to detect and correct errors.
  4. Flow Control: Manages the rate of data transmission to avoid congestion.
  5. Congestion Control: Adjusts data transmission based on network conditions.
  6. Data Sequencing: Ensures packets are received in the correct sequence.

Q5) Attempt any ONE of the following (Out of TWO): [1 × 3 = 3]

a) Write & Draw Bluetooth Frame Format.

A Bluetooth frame consists of the following fields:

  1. Access Code (72 bits):
    • Used for synchronization and identification.
  2. Header (54 bits):
    • Contains information like address, flow control, acknowledgment, and error checking.
  3. Payload (0-2745 bits):
    • Contains the actual data being transmitted.

(A simple diagram can be drawn to represent these sections as labeled boxes.)

b) Explain Multiplexing & Demultiplexing at the Transport Layer.

  • Multiplexing:
    • At the sender’s side, data from multiple applications is collected and transmitted over a network using unique port numbers. This helps in combining multiple data streams.
    • Example: Sending data from a web browser and an email client through the same network connection.
  • Demultiplexing:
    • At the receiver’s side, the transport layer separates incoming data and delivers it to the correct application using port numbers.
    • Example: Receiving data at port 80 for a web browser and port 25 for an email client.

This comprehensive explanation covers all the questions with clarity and in simple terms. Let me know if you’d like more details on any specific point!

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