GROUP-A
* Answer ALL questions.
a) A group of devices connected with one another is known as a network.
b) The Internet is the largest network in the world.
c) MAC stands for Media Access Control.
d) PPP stands for Point-to-Point Protocol.
e) ATM stands for Asynchronous Transfer Mode.
f) The length of IPv4 address is 32 bits.
g) Router device is used in network layer.
h) HTTP (Hypertext Transfer Protocol) protocol used to make hypertext document readable on
WWW explanation.
GROUP-B
* Answer any EIGHT within TWO to THREE sentences.
a) Differentiate between switch and hub.
A hub is a basic networking device that broadcasts all incoming data packets to every
connected device on the network. A switch, on the other hand, is a more intelligent device that
learns the MAC addresses of connected devices and forwards data packets only to the intended
recipient, which reduces unnecessary traffic and improves network efficiency.
b) Define the Bridge.
A bridge is a network device that connects two separate local area networks (LANs) or network
segments. It operates at the data link layer (Layer 2) of the OSI model and can filter traffic by
forwarding data frames between segments based on their MAC addresses, effectively creating
a single, larger network.
c) What is line coding?
Line coding is the process of converting digital data into a digital signal that can be transmitted
over a physical medium. It involves using a set of rules to represent binary data (0s and 1s) with
variations in a physical signal, such as changes in voltage, current, or light intensity. This is
essential for ensuring reliable data transmission.
d) What are the possible ways of data exchange?
The three primary ways of data exchange are simplex, half-duplex, and full-duplex. In simplex
mode, data can only be transmitted in one direction. In half-duplex, data can travel in both
directions, but not simultaneously. In full-duplex, data can be transmitted in both directions at
the same time.
e) Explain Coaxial cable with diagram.
A coaxial cable is a type of electrical cable consisting of a central conductor wire surrounded by
an insulating layer, a metallic shield, and an outer insulating jacket. The central conductor
carries the data signal, and the outer shield protects the signal from external electromagnetic
interference. This design makes it suitable for high-frequency signal transmission over longer
distances.
f) What is CRC?
CRC stands for Cyclic Redundancy Check. It is an error-detecting code used in digital networks
and storage devices to check for accidental changes to raw data. It works by calculating a
checksum based on the data block and appending it to the data before transmission. The
receiver then recalculates the checksum and compares it to the received one
to detect any errors.
g) Define the bandwidth.
Bandwidth refers to the maximum amount of data that can be transmitted over a communication
channel or link in a given amount of time. It is typically measured in bits per second (bps). A
higher bandwidth indicates a faster data transfer rate, allowing more information to be sent in
the same timeframe.
h) What is WIFI?
Wi-Fi is a wireless networking technology that allows devices like computers, smartphones, and
tablets to connect to the internet or communicate with each other over a short range. It uses
radio waves to transmit data and is based on the IEEE 802.11 standards.
i) Explain the types of error.
In data communication, there are two main types of errors: single-bit errors and burst errors. A
single-bit error occurs when only one bit in a data unit is corrupted during transmission. A burst
error, on the other hand, occurs when two or more consecutive bits in a data unit are changed.
j) Define the term TDM.
TDM stands for Time Division Multiplexing. It is a technique used to transmit multiple signals
simultaneously over a single communication channel by dividing the channel's time into
discrete, non-overlapping time slots. Each signal is allocated a specific time slot, and they are
transmitted in a rotating sequence.
GROUP-C
* Answer any 8 questions.
a) Differentiate between analog signal and digital signal.
Analog signals are continuous waves that vary smoothly over time, representing data through
changes in amplitude, frequency, or phase. They are susceptible to noise and degradation.
Digital signals are discrete, represented by a finite set of values, typically binary (0s and 1s).
They are more robust against noise and can be easily processed and stored.
b) Discuss about different types of transmission mode.
The three types of transmission modes are simplex, half-duplex, and full-duplex. In simplex
mode, communication is one-way, like a radio broadcast. In half-duplex mode, communication is
two-way but not at the same time, like a walkie-talkie. In full-duplex mode, communication is
simultaneous in both directions, like a telephone call.
c) What are the criteria necessary for an effective & efficient network?
An effective and efficient network must satisfy several criteria, including performance, reliability,
and security. Performance is measured by throughput and delay, indicating how fast and
efficiently data is transmitted. Reliability ensures that the network is available when needed and
can recover from failures. Security involves protecting data from unauthorized access and cyber
threats.
d) What are the key elements of a protocol?
Key elements of a protocol include syntax, semantics, and timing. Syntax refers to the structure
or format of the data, including the order of bits and fields. Semantics relates to the meaning of
each section of the data, such as what a specific field represents. Timing dictates when and at
what speed data should be sent or received.
e) What is Go-Back-n ARQ and Selective Repeat ARQ.
Go-Back-N ARQ is a data link layer protocol where the sender can transmit multiple frames
without waiting for an acknowledgment for each one. If a frame is lost or corrupted, the receiver
discards that frame and all subsequent frames, and the sender must retransmit the lost frame
and all subsequent frames from that point. Selective Repeat ARQ, on the other hand, allows the
receiver to accept and buffer frames that arrive after a corrupted one. The sender only
retransmits the specific frame that was lost or corrupted, which is more efficient.
f) Differentiate between circuit switching and packet switching?
In circuit switching, a dedicated communication path is established between the sender and
receiver before data transmission begins and remains for the entire duration of the
communication. It guarantees a constant data rate but is inefficient for bursty data. In packet
switching, data is broken into smaller packets that are routed independently over shared
network resources. It is more efficient for bursty data and more resilient to network failures but
does not guarantee a constant data rate.
g) Define the checksum.
A checksum is a small-sized block of data derived from a larger block of digital data. It is used to
detect errors that may have been introduced during transmission or storage. The sender
calculates the checksum and sends it along with the data. The receiver then recalculates the
checksum from the received data and compares it to the transmitted checksum to determine if
any corruption has occurred.
h) Differentiate between public key and private key.
In public-key cryptography, a user has a pair of keys: a public key and a private key. The public
key can be shared freely and is used to encrypt data or verify a digital signature. The private key
is kept secret by the owner and is used to decrypt data that was encrypted with the
corresponding public key or to create a digital signature.
i) Define the single parity bit.
A single parity bit is a simple error-detection technique where an extra bit, called the parity bit, is
added to a block of data. The value of this bit is set to ensure that the total number of '1's in the
data and the parity bit is either even (for even parity) or odd (for odd parity). The receiver checks
this condition to detect if a single-bit error has occurred.
j) Differentiate between digital signature and digital certificate.
A digital signature is a cryptographic mechanism used to authenticate the identity of the sender
and ensure the integrity of a message. It is a hash of the message encrypted with the sender's
private key. A digital certificate, on the other hand, is an electronic document that links a public
key to an individual or organization. It is issued by a trusted third party, known as a Certificate
Authority, to verify the ownership of the public key.
GROUP-D
4 a) Discuss about different types of topology in detail with suitable diagram.
Network topology refers to the physical or logical arrangement of connected devices in a
network. The main types of topologies are:
* Bus Topology: All devices are connected to a single central cable. It is simple and cheap but
prone to single points of failure, as a break in the cable brings down the entire network.
* Star Topology: All devices are connected to a central hub or switch. It is easy to manage
and a failure of one device does not affect others. However, the central hub is a single point of
failure.
* Ring Topology: Devices are connected in a closed loop, with each device connected to
exactly two others. Data travels in one direction. It is efficient for data transmission but a break
in one link can affect the entire ring.
* Mesh Topology: Every device is connected to every other device in the network. It provides
high reliability and fault tolerance due to multiple paths for data. However, it is very expensive
and complex to install and manage.
* Tree Topology: It is a hybrid of bus and star topologies. Multiple star networks are connected
to a central bus. It allows for network expansion and is easy to manage but relies on the central
bus, which is a single point of failure.
4.b) Explain about seven layer of OSI model in detail.
The Open Systems Interconnection (OSI) model is a conceptual framework that standardizes
the functions of a communication system into seven abstract layers.
* Physical Layer: Deals with the physical transmission medium, such as cables, and defines
voltage levels, data rates, and physical connections.
* Data Link Layer: Provides error-free transfer of data frames from one node to another over
the physical layer, handling framing, flow control, and error control.
* Network Layer: Responsible for logical addressing (IP addresses) and routing data packets
across different networks. It determines the best path for data.
* Transport Layer: Ensures end-to-end data delivery, handling segmentation, reassembly, and
flow control. Protocols here include TCP and UDP.
* Session Layer: Establishes, manages, and terminates connections (sessions) between
applications, handling synchronization and dialogue control.
* Presentation Layer: Translates data from the application format to a format suitable for
network transmission, and handles data encryption and compression.
* Application Layer: Provides the interface for users to interact with the network, including
protocols for email (SMTP), file transfer (FTP), and web browsing (HTTP).
*
5.a) Discuss various digital conversion with a suitable example.
Digital-to-digital conversion involves converting digital data into a digital signal. The main
types are:
* Line Coding: This is the most common method. Data bits are represented by a signal
pattern. Examples include NRZ (Non-Return-to-Zero), where a 1 is a positive voltage and a 0 is
a zero voltage, and Manchester coding, where each bit transition is at the middle of the bit
interval, useful for clock synchronization.
* Block Coding: This method groups bits into blocks and adds redundancy for error detection.
For example, in 4B/5B, a 4-bit data block is converted into a 5-bit code.
* Scrambling: This technique substitutes sequences of bits that could lead to synchronization
problems (e.g., long strings of 0s) with sequences that are less problematic. B8ZS is an
example used to handle long sequences of zeros.
5.b) Explain about different types of transmission media in computer network.
Transmission media are the physical pathways over which data travels. They are broadly
categorized into two types:
* Guided Media: These media guide the signal along a specific path. Examples include:
* Twisted-Pair Cable: Consists of two insulated copper wires twisted together to reduce
electromagnetic interference. It is used in Ethernet networks.
* Coaxial Cable: Has a central conductor surrounded by an insulating layer and a metallic
shield, providing good protection against noise. Used in cable TV and some older networks.
* Fiber-Optic Cable: Transmits data using light signals through a thin glass or plastic fiber. It
offers very high bandwidth, long distance transmission, and immunity to electromagnetic
interference.
* Unguided Media (Wireless): These media do not guide the signal, which propagates through
the air, vacuum, or water. Examples include:
* Radio Waves: Used in Wi-Fi, cellular networks, and satellite communication. They are easy
to generate and can travel long distances.
* Microwaves: Used for point-to-point communication and satellite links. They require line of
sight.
* Infrared: Used for short-range communication, such as TV remote controls. It cannot
penetrate walls.
6.a) Explain the flow control mechanism in detail.
Flow control is a mechanism that ensures the sending device doesn't overwhelm the receiving
device with more data than it can process. It prevents buffer overflow and data loss.
* Stop-and-Wait: The sender transmits one frame and then waits for an acknowledgment
(ACK) from the receiver before sending the next one. This is simple but inefficient.
* Sliding Window: Both the sender and receiver maintain a "window" of frames. The sender
can transmit multiple frames (up to the window size) without waiting for an acknowledgment.
The receiver can also acknowledge a group of frames. This is much more efficient than stop-
and-wait as it allows for pipelining of data. The size of the window can be adjusted based on the
receiver's capacity.
6.b) Write a short note on HDLC.
HDLC (High-level Data Link Control) is a bit-oriented protocol for communication over point-to-
point and multipoint links. It is a standard for data link layer communication. It provides both flow
control and error control. HDLC frames have a specific structure, including a flag field to mark
the start and end of the frame, address and control fields, and a payload. It supports three types
of stations (primary, secondary, and combined) and three modes of operation (Normal
Response Mode, Asynchronous Response Mode, and Asynchronous Balanced Mode).
7 a) Write short notes on:
i. DNS
DNS (Domain Name System) is a hierarchical and decentralized naming system for
computers, services, and other resources connected to the Internet or a private network. It
translates human-readable domain names (like www.google.com) into IP addresses (like
142.250.191.46), which are required for network communication. It works like a phonebook for
the internet, making it easy for users to find websites without memorizing complex IP
addresses.
ii. FTP
FTP (File Transfer Protocol) is a standard network protocol used for the transfer of computer
files from a server to a client on a computer network. It operates on a client-server model and
uses separate control and data connections between the client and the server. The control
connection is used for commands and responses, while the data connection is used for
transferring the actual file.
7b) Discuss about any two functionality of transport layer and differentiate between UDP and
TCP.
Two key functionalities of the transport layer are segmentation and reassembly and end-to-end
communication. Segmentation involves breaking down a large message from the application
layer into smaller, manageable chunks called segments. Reassembly is the reverse process at
the receiving end. The transport layer also provides end-to-end communication, ensuring that
data is delivered from the source host to the destination host.
TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are the two main
protocols at the transport layer.
* TCP is a connection-oriented protocol, meaning it establishes a connection before
transmitting data. It provides reliable, ordered, and error-checked delivery of a stream of bytes.
It's used for applications where data integrity is crucial, such as file transfers and web browsing.
* UDP is a connectionless protocol. It does not establish a connection and simply sends data
packets (datagrams) without any guarantee of delivery, order, or error checking. It is faster and
has less overhead than TCP, making it suitable for applications that prioritize speed over
reliability, such as streaming video, online gaming, and VoIP.
