Q1) Attempt any EIGHT of the following (out of TEN): [8×1=8]
a) List components of data communication:
- Message – The data to be communicated is called the message. For eg. Text, Image, etc.
- Sender – The device that sends the message.
- Receiver – The device that gets the message.
- Medium – The path used to send the message (like cables or air for wireless).
- Protocol – The rules that guide how the message is sent and received.
b) What is data communication?
It is the process of sending and receiving data between two devices using a medium like wires or wireless signals.
c) Define Protocols.
Protocols are rules that devices follow to communicate with each other properly.
d) List any two channelization protocols:
- FDMA (Frequency Division Multiple Access) – Divides the channel into frequency bands.
- TDMA (Time Division Multiple Access) – Divides the channel by giving each user a time slot.
e) State any two applications of wireless LAN:
- Using Wi-Fi to access the internet in places like airports or cafes.
- Connecting devices like laptops and smartphones in offices.
f) What is bandwidth?
It is the amount of data that can be sent over a network in a given time.
g) Define congestion.
Congestion happens when too much data is sent on a network, causing delays and data loss.
h) What is Routing?
Routing is finding the best path for data to travel from one device to another.
i) What is a Port Number?
A port number helps identify specific services or programs on a device so the data goes to the right place.
j) What is internetworking?
It is connecting different networks so devices can communicate with each other.
Here are simple answers to the given questions:
Q2) Attempt any FOUR of the following (out of FIVE): [4×2=8]
a) What is a Computer Network? Write any four characteristics of a Computer Network.
Computer network is a collection of autonomous computers interconnected by a single technology . Two computers are said to be interconnected if they are able to exchange the information.
Four characteristics of a computer network:
- Sharing Resources – Devices can share printers, files, and internet connections.
- Reliability – Network reliability is measured by the frequency of failure. Networks ensure data is sent and received correctly.
- Scalability – New devices can be easily added to the network.
- Security – Network security issues include protecting data from unauthorised access, protecting data from damage and implementing policies and procedures for recovery from Data losses.
- Performance – The performance of a network depends on a number of factors including a number of users, the type of transmission medium and the capabilities of the connected hardware and software.
b) What is LAN? Write any two advantages of LAN.
A LAN (Local Area Network) is a privately owned network connecting devices within a single room, building or campus extending up to a few kilometer in size. The primary application of LAN is to share resource and exchange information by connecting PCs, workstations and other hardware in office organisation and institutes.
Two advantages of LAN:
- Resources such as data, hard disc drives, printers etc. can be easily shared.
- Less expensive to install and maintain.
- High speed data communication is possible between machines in a LAN.
- Improve data security.
- Software such as compilers, word processing applications, licence software, etc. can be install on the server and share by all machines in the network.
c) Consider a noiseless channel with a bandwidth of 4000 Hz transmitting a signal with two signal levels. What will be the maximum bit rate?
Using the Nyquist formula:
Maximum Bit Rate = 2 × Bandwidth × log₂(Number of Signal Levels)
= 2 × 4000 × log₂(2)
= 2 × 4000 × 1
= 8000 bits per second (bps)
d) Write any four applications of Bluetooth technology:
- It allows a transfer of images, word document, applications, audio and video files between devices without the help of cables.
- It can be used for remote cells technology allowing wireless access to vending machines and other commercial enterprises.
- It provide inter accessibility of PDAs and desktops for file and data exchanges.
- It can be used to set up a personal area network(PAN) or wireless personal area network(WPAN).
e) Change the following IPv4 address from binary to dotted decimal notation:
i) 10000001 00001011 00001011 11101111
= 129.11.11.239
ii) 11000001 10000011 00011011 11111111
= 193.131.27.255
Q3) Attempt any TWO of the following (Out of THREE): [2 × 4 = 8]
a) Comparison of OSI Reference Model and TCP/IP Model
| Feature | OSI Model | TCP/IP Model |
|---|---|---|
| Full Form | Open Systems Interconnection Model | Transmission Control Protocol/Internet Protocol Model |
| Layers | Consists of 7 layers: Physical, Data Link, Network, Transport, Session, Presentation, Application | Consists of 4 layers: Network Interface, Internet, Transport, Application |
| Development | Developed by ISO (International Standards Organization) | Developed by the Department of Defense (DoD) |
| Approach | Theoretical and conceptual model | Practical and protocol-oriented model |
| Protocols | Does not specify protocols for each layer | Specifies standard protocols like TCP, IP, HTTP, etc. |
| Flexibility | More flexible and generalized model | More rigid and based on standard internet protocols |
| Usage | Mainly used for understanding and teaching networking concepts | Used for real-world networking and internet communication |
| Layer Functions | Each layer performs a specific function and provides services to the next layer | Functions are more combined and flexible across fewer layers |
b) Important Design Issues of the Data Link Layer
The Data Link Layer is responsible for reliable communication between two directly connected nodes. The key design issues include:
- Framing:
- This is the most important task performed by the data link layer.
- To transmit data from one point to another.
- It encapsulates data packets into frames for transmission.The process of dividing data into manageable units called frames.
- It helps in identifying where one frame starts and another ends.
- Addressing :
- Each communicating machine in the network is identify by a unique address.
- Data link layer addresses are called physical addresses or MAC addresses.
- They identify the next node in a point to delivery scheme.
- Error Control:
- Ensures that the transmitted data is free from errors.
- Techniques like checksums, cyclic redundancy checks (CRC), and acknowledgments are used to detect and correct errors.
- Flow Control:
- Prevents the sender from overwhelming the receiver with too much data.
- Techniques like sliding window protocol and stop-and-wait are used to manage data flow.
- Access Control:
- Determines how devices share the communication medium (especially in networks like Ethernet).
- Protocols like CSMA/CD (Carrier Sense Multiple Access with Collision Detection) are used.
c) Different Services Offered by the Network Layer
The Network Layer is responsible for the delivery of data from the source to the destination across multiple networks. The main services include:
- Routing:
- Determines the best path for data packets to travel from the source to the destination.
- Uses algorithms and routing tables to make decisions.
- Logical Addressing:
- Assigns logical addresses (like IP addresses) to devices to ensure unique identification across networks.
- Packet Forwarding:
- Moves packets from the source towards the destination, ensuring they pass through intermediate routers.
- Fragmentation and Reassembly:
- If packets are too large for a network, the layer breaks them into smaller fragments.
- At the destination, these fragments are reassembled to form the original packet.
- Error Handling and Diagnostics:
- Handles errors in packet delivery and provides diagnostic functions like ICMP (Internet Control Message Protocol) to report issues.
- Quality of Service (QoS):
- Ensures data is delivered with the required speed and reliability, especially for real-time data like video or voice.
These explanations cover the key concepts in simple terms while providing a detailed understanding.
Here are the detailed explanations for the given questions:
Q4) Attempt any TWO of the following (Out of THREE): [2 × 4 = 8]
a) Four Differences Between Fast Ethernet and Gigabit Ethernet
| Feature | Fast Ethernet | Gigabit Ethernet |
|---|---|---|
| Speed | Offers a data transfer speed of 100 Mbps | Offers a data transfer speed of 1000 Mbps (1 Gbps) |
| Standard | Defined by the IEEE 802.3u standard | Defined by the IEEE 802.3ab standard |
| Cabling | Typically uses Cat5 cables | Requires Cat5e, Cat6, or fiber optic cables for higher speeds |
| Usage | Suitable for small networks with moderate data needs | Suitable for high-speed networks with large data transfer requirements |
| Cost | More affordable and widely available | Relatively expensive due to higher speed and advanced infrastructure |
b) Eight Features of the IPv6 Protocol
- Larger Address Space:
- IPv6 uses 128-bit addresses, allowing for a massive number of unique IP addresses compared to IPv4’s 32-bit addresses.
- Simplified Header Format:
- IPv6 has a simplified and more efficient header, which improves routing and processing efficiency.
- Auto-configuration:
- Supports stateless address autoconfiguration (SLAAC), allowing devices to configure their own IP addresses automatically.
- Improved Security:
- IPv6 was designed with IPSec (Internet Protocol Security) as a mandatory feature for secure data transmission.
- No Need for NAT:
- Due to its vast address space, IPv6 eliminates the need for Network Address Translation (NAT), simplifying network configurations.
- Better Multicast and Anycast Support:
- IPv6 supports efficient multicast (one-to-many) and anycast (one-to-nearest) transmission methods.
- Enhanced Mobility:
- IPv6 provides better support for mobile devices, ensuring continuous connectivity during network changes.
- Efficient Routing:
- The simplified header and hierarchical address allocation improve routing efficiency and reduce processing time.
c) Four Features Supported by TCP (Transmission Control Protocol)
- Connection-Oriented Protocol:
- TCP establishes a connection between the sender and receiver before data transfer, ensuring reliable communication.
- Reliable Data Transfer:
- TCP guarantees the delivery of data packets in the correct order. If packets are lost or corrupted, TCP retransmits them.
- Error Detection and Correction:
- TCP uses checksums to detect errors in the transmitted data. It also uses acknowledgments (ACKs) to confirm successful data delivery.
- Flow Control:
- TCP uses mechanisms like the sliding window protocol to control the flow of data, ensuring that the sender doesn’t overwhelm the receiver.
- Congestion Control:
- TCP monitors network congestion and adjusts the data transmission rate to avoid packet loss and ensure smooth communication.
- Ordered Data Transfer:
- TCP ensures that data packets are delivered in the same order in which they were sent, even if they arrive out of order.
- Full-Duplex Communication:
- TCP supports simultaneous two-way data transmission between devices.
- Stream-Oriented:
- TCP treats data as a continuous stream of bytes, allowing for efficient data transmission without worrying about packet sizes.
These explanations provide a clear understanding of the key concepts and differences in simple terms.
a) Datagram Format of UDP (User Datagram Protocol)
UDP is a simple, connectionless protocol used for sending data packets, called datagrams, across networks. Each UDP datagram has a specific format consisting of the following fields:
- Source Port (16 bits):
- This is the port number of the sender’s application. It helps the receiver know where the data is coming from.
- Destination Port (16 bits):
- This is the port number of the receiver’s application, ensuring the data is delivered to the correct process.
- Length (16 bits):
- It indicates the total length of the UDP datagram, including the header and data. The minimum length is 8 bytes (just the header).
- Checksum (16 bits):
- This field is used for error checking. It ensures that the data hasn’t been corrupted during transmission.
- Data (Variable Length):
- This is the actual payload or message that needs to be transmitted. Its size can vary depending on the application.
Key Points:
- UDP is faster but less reliable than TCP because it doesn’t guarantee delivery, order, or error correction.
- It is commonly used in real-time applications like video streaming, VoIP, and online gaming where speed is crucial.
b) Define Polling
Polling is a method used in computer systems and networks where a central controller (like a CPU or server) repeatedly checks each connected device to see if it needs attention or has data to send.
Key Points about Polling:
- It is a synchronous process where the controller asks devices one by one if they need service.
- Commonly used in scenarios like I/O device management, where the CPU checks if a printer or disk is ready for data.
- While simple, polling can be inefficient as it wastes time checking devices that have nothing to report.
- To improve efficiency, alternatives like interrupts are used, where devices signal the CPU only when they need attention.