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CCN 2023 Regular (NEP & CBCS) Questions with Answers (Important)

Section - A

1. Answer any Six question.

1. What is computer network?

It refers to interconnected computing device that can exchange data and share resources with each other. 

2. Define topology. Give example.

Topology defines the structure of the network of how all the components are interconnected to each other.   Example :

      1. Bus network topology

      2. Ring network topology

      3. Star network topology

      4. Mesh network topology

3. Name any two guided transmission Mediums.

There are three basic types of guided media which are as follows −

  • Twisted pair cable,
  • Co-axial cable
  • Fibre-optic cable.
4. Define switching.

Switching is the process of transferring data packets from one device to another in a network, or from one network to another, using specific devices called switches.

5. What is parity bit?

A parity bit, also known as a check bit, is a single bit that is added to a string of binary code. It is used to detect errors in the data.

6. Define CRC.

Cyclic redundancy check (CRC) is an error detection code commonly used in digital networks and storage devices to detect accidental changes to digital data.

CRCs are used in a wide variety of applications, including:

    • File transfers
    • Data storage
    • Network communication
    • Error-correcting codes
7. What do you mean by flooding?

Flooding in computer networks is a technique in which a node sends a packet to all of its outgoing links, except for the link on which the packet arrived. This can be used to distribute information to all nodes in a network, or to find a specific node in a network.

8. What is Hop by Hop chock packet?

A hop-by-hop choke packet is a message sent by a router to a source host to inform it of congestion. The choke packet is sent when the router’s buffers become full and it is unable to accept any more packets.

9. Expand DNS and TCP/IP.
  • Domain Name System
  • Transmission Control Protocol/Internet Protocol.
10. What is electronic mailing?

Electronic mailing, also known as email, is a method of exchanging messages between people using electronic devices. It is one of the most popular forms of communication in the world, and is used by billions of people every day.

11. Define WWW.

The World Wide Web (WWW), also known as the Web, is a system of interlinked hypertext documents that are accessed via the Internet. A document on the Web is identified by a Uniform Resource Locator (URL).

12. Write the purpose of multiplexing.

The purpose of multiplexing is to allow multiple signals to be transmitted over a single medium. This is done by combining the signals into a single composite signal.

Section - B

Answer any FOUR questions, each carries 5 marks. (4×5=20)

13. Explain the types of computer networks.

     1.LAN

  1. Is a collection of devices connected together in one physical location such as building, campus , home.
  2. A LAN comprises cables access points switches and routers.
  3. LAN connects devices that are in single and limited area.
  4. LAN is used for connecting two or more personal computers through a communication medium such as twisted pair, coaxial cable.
  5. The data is transferred at an extremely faster rate in Local Area Network.
  6. The range from 100Mbps to 1000 Mbps.

     2.MAN

  1. Is a network that connects computer within a metropolitan area which can be a large city or town.
  2. A metropolitan area network (MAN) is a network with a size greater than LAN but smaller than a WAN.
  3. It facilitates sharing of regional resources.
  4. Data rates are moderate to high.
  5. Network size generally ranges from 5 to 50km . It is may be small as a group of buildings in a campus to as large as covering the whole city.
  6. They provide uplinks for connecting LANs to WANs and Internet.
  7. The Metropolitan Area Network ensures the transmission of high-quality voice, data, and video.
  8. Example : Cable TV network , Telephone networks.

      3.WAN

  1. A wide area network (WAN) is a computer network that covers a large geographical area comprising a region , a country, a continent or even the whole world.
  2. WAN includes the technologies to transmit data , image, audio and video information over a long distances and among different LANs and MANs.
  3. They provide uplinks for connecting LANs and MANs to the Internet.
  4. WANs have larger capacity, connecting a large number of computers over a large area, and are inherently scalable.
  5. Communication links are provided by public carriers like telephone networks, network providers , cable system, satellites etc.
  6. They have low transfer rate and high propagation delay, i.e. they have low communication speed.
14. Describe any two unguided transmission media.

      1.Radio wave transmission :

    1. A radio wave is generated by a transmitter and they detected by a receiver.
    2. The wave having the longest wavelength in the electromagnetic spectrum.
    3. Example : AM and FM radio broadcasting , radar, Bluetooth ,mobile phones and wireless computer networks.
    4. Radio wave is the longer than the infrared light(wave).
    5. Radio waves can travel for a long distance.
    6. Radio waves are cannot be felt and they are invisible.
    7. Radio waves are used in standard broadcast radar and television.

       2.Microwave transmission.

    1. It is a line of site transmission i.e. sending and receiving antennas need to be properly aligned with each other.
    2. The distance covered by signal is directly proportional to the height of the antenna.
    3. Frequency range is 1 GHz to 300GHz.
    4. These are majorly used for mobile communication and television distribution.
    5. Microwaves propagation is line-of-sight.
    6. It is very high –frequency microwaves cannot penetrate walls.
15. Explain CRC with an example.

Cyclic redundancy check (CRC) is an error-detecting code that is used to check the integrity of data. It works by adding a checksum to the data, which is a value that is calculated based on the data itself. The checksum is then transmitted along with the data. When the data is received, the checksum is recalculated and compared to the transmitted checksum. If the two checksums match, then the data is assumed to be error-free. If the two checksums do not match, then the data is assumed to be corrupt.

CRC is based on the theory of cyclic error-correcting codes. It uses a generator polynomial, which is a special polynomial that is used to generate the CRC checksum.

To generate a CRC checksum, the data is divided by the generator polynomial using polynomial division. The remainder of the division is the CRC checksum.

To verify the integrity of data, the CRC checksum is recalculated and compared to the transmitted checksum. If the two checksums match, then the data is assumed to be error-free. If the two checksums do not match, then the data is assumed to be corrupt.

  Example: 
16. Explain distance vector routing algorithm with neat diagram.

Distance vector routing algorithm is also called as Bellman-Ford algorithm or Ford Fulkerson algorithm as this algorithm is used to find the shortest route from one node to another node in the network.

The routing protocol is used to calculate the best route from source to destination based on the distance or hops as its primary metric to define an optimal path. The distance vector refers to the distance to the neighbor nodes, where routing defines the routes to the established node. 

The Distance Vector routing algorithm(DVR) shares the information of the routing table with the other routers in the network and keeps the information up-to-date to select an optimal path from source to destination.

The Bellman-Ford algorithm is defined as :

17.Explain the functions of electronic mailing.

Electronic mailing, also known as email, is a method of exchanging messages between people using electronic devices. It is one of the most popular forms of communication in the world, and is used by billions of people every day.

Email has a number of functions, including:

  • Communication: Email can be used to communicate with people all over the world, regardless of their location or time zone. This makes it a very convenient and efficient way to stay in touch with friends, family, colleagues, and customers.
  • Collaboration: Email can be used to collaborate on projects and tasks with people who are located in different places. This can be done by sharing documents, files, and ideas via email.
  • Information sharing: Email can be used to share information with people all over the world. This can be done by sending them articles, blog posts, links, and other types of content.
  • Marketing: Email can be used to market products and services to customers. This can be done by sending them promotional emails, newsletters, and other types of marketing materials.
  • Customer support: Email can be used to provide customer support to customers. This can be done by answering their questions and resolving their issues.

Email is a very versatile communication tool that can be used for a variety of purposes. It is a convenient, efficient, and cost-effective way to communicate with people all over the world.

  • Personal
  • Business
  • Education
  • Government

Section - C

Answer any TWO questions, each carries 10 marks. (2×10=20)

18.Explain OSI reference model.

OSI stands for Open System Interconnectionis a reference model that describes how information from a software application in one computer moves through a physical medium to the software application in another computer.

OSI consists of seven layers, and each layer performs a particular network function.

OSI model was developed by the International Organization for Standardization (ISO) in 1984, and it is now considered as an architectural model for the inter-computer communications.

 1.Application Layer

  • An application layer serves as a window for users and application processes to access network service.
  • It handles issues such as network transparency, resource allocation, etc.
  • An application layer is not an application, but it performs the application layer functions.
  • This layer provides the network services to the end-users.

                       Functions of the Transport layer

      • File transfer, access, and management (FTAM): 
      • Mail Services
      • Directory Services

  2.Presentation Layer

  • A Presentation layer is mainly concerned with the syntax and semantics of the information exchanged between the two systems.
  • It acts as a data translator for a network.
  • This layer is a part of the operating system that converts the data from one presentation format to another format.
  • The Presentation layer is also known as the syntax layer.

                     Functions of the Transport layer

      • Encryption
      • Decryption
      • Translation

3.Session Layer

  • It is a layer 3 in the OSI model.
  • The Session layer is used to establish, maintain and synchronizes the interaction between communicating devices.

                      Functions of the Network layer

      • Dialog Control
      • Synchronization

4.Transport Layer

  • The Transport layer is a Layer 4 ensures that messages are transmitted in the order in which they are sent and there is no duplication of data.
  • The main responsibility of the transport layer is to transfer the data completely.
  • It receives the data from the upper layer and converts them into smaller units known as segments.
  • This layer can be termed as an end-to-end layer as it provides a point-to-point connection between source and destination to deliver the data reliably.

                     Functions of the Transport layer

      • Connection mode and connectionless mode transmissions
      • Same order delivery
      • Data integrity
      • Flow control
      • Congestion avoidance
      • Multiplexing

 

5.Network Layer

  • It is a layer 3 that manages device addressing, tracks the location of devices on the network.
  • It determines the best path to move data from source to the destination based on the network conditions, the priority of service, and other factors.
  • The Data link layer is responsible for routing and forwarding the packets.
  • Routers are the layer 3 devices, they are specified in this layer and used to provide the routing services within an internetwork.
  • The protocols used to route the network traffic are known as Network layer protocols. Examples of protocols are IP and Ipv6.

                     Functions of the Network layer

      • Internet working
      • Addressing
      • Routing
      • Packetizing

 

6.Data-Link Layer

  • This layer is responsible for the error-free transfer of data frames.
  • It defines the format of the data on the network.
  • It provides a reliable and efficient communication between two or more devices.
  • It is mainly responsible for the unique identification of each device that resides on a local network.

                      Functions of the Data-link layer

      • Farming
      • Physical Addressing
      • Flow Control
      • Error Control
      • Access Control

7.Physical layer

  • The main functionality of the physical layer is to transmit the individual bits from one node to another node.
  • It is the lowest layer of the OSI model.
  • It establishes, maintains and deactivates the physical connection.
  • It specifies the mechanical, electrical and procedural network interface specifications.

                     Functions of a Physical layer:

      • Line Configuration
      • Data transmission
      • Topology
      • Signals
19. a & b
a. Explain message switching.
  • Is the mechanism in computer networks that helps in finding the best route for data transmission if there are multiple paths in a larger networks.
  • Message Switching is a switching technique in which a message is transferred as a complete unit and routed through intermediate nodes at which it is stored and forwarded.
  • In Message Switching technique, there is no establishment of a dedicated path between the sender and receiver.
  • Message switches are programmed in such a way so that they can provide the most efficient routes.
  • Message switching treats each message as an independent entity.

Advantages Of Message Switching

  • Data channels are shared among the communicating devices that improve the efficiency of using available bandwidth.
  • Traffic congestion can be reduced because the message is temporarily stored in the nodes.
  • Message priority can be used to manage the network.
  • The size of the message which is sent over the network can be varied. Therefore, it supports the data of unlimited size.

Disadvantages Of Message Switching

  • The message switches must be equipped with sufficient storage to enable them to store the messages until the message is forwarded.
  • The Long delay can occur due to the storing and forwarding facility provided by the message switching technique.
b. Explain Go Back N sliding window protocol.

Go-Back-N (GBN) is a sliding window protocol that is used to provide reliable data transmission over unreliable networks. It works by allowing the sender to transmit multiple packets without waiting for an acknowledgement for each packet. The receiver sends a cumulative acknowledgement (ACK) for a sequence of packets, indicating the last correctly received packet. If any packet is lost, the receiver does not send an ACK for that packet or any subsequent packets. The sender times out if it does not receive an ACK for a packet within a certain amount of time, and then retransmits all of the packets that have not been acknowledged.

The following diagram shows how the Go-Back-N protocol works:

The sender has a window of size N, which is the number of packets that it can transmit without waiting for an acknowledgement. The receiver has a window of size 1, which means that it can only receive and process one packet at a time.

The sender starts by transmitting the first packet in its window. The receiver receives the packet and sends an ACK for it. The sender then transmits the next packet in its window. This process continues until the sender reaches the end of its window or until it receives an ACK for the last packet in its window.

If any packet is lost, the receiver will not send an ACK for that packet or any subsequent packets. The sender will time out if it does not receive an ACK for a packet within a certain amount of time. When the sender times out, it retransmits all of the packets that have not been acknowledged.

The Go-Back-N protocol is a simple and effective way to provide reliable data transmission over unreliable networks. However, it has one disadvantage: it can be inefficient if there are a lot of lost packets. This is because the sender will have to retransmit all of the packets that have not been acknowledged, even if only a few packets were lost.

 

20.
a. Explain leaky bucket and token bucket algorithm..

The leaky bucket and token bucket algorithms are both flow control algorithms that can be used to limit the rate at which data is sent over a network.

Leaky bucket algorithm

The leaky bucket algorithm works like a leaky bucket with a hole in the bottom. Data is poured into the bucket at a certain rate, and it leaks out of the hole at a fixed rate. If the data is poured into the bucket faster than it can leak out, the bucket will overflow and the excess data will be dropped.

The leaky bucket algorithm can be used to limit the rate at which data is sent over a network by setting the leak rate to the maximum desired rate of data transmission. If the sender tries to send data faster than the leak rate, the data will be dropped.

Token bucket algorithm

The token bucket algorithm works like a bucket with tokens in it. Tokens are added to the bucket at a certain rate, and the sender can only send data if there are enough tokens in the bucket.

The token bucket algorithm can be used to limit the rate at which data is sent over a network by setting the token rate to the maximum desired rate of data transmission. If the sender tries to send data faster than the token rate, the data will be blocked until there are enough tokens in the bucket.

Here are some examples of where the leaky bucket and token bucket algorithms can be used:

Leaky bucket algorithm:

  • Limiting the rate at which a user can download files from a server
  • Limiting the rate at which a user can upload files to a server
  • Limiting the rate at which a router can forward packets

Token bucket algorithm:

  • Shaping the traffic of a real-time video streaming application
  • Shaping the traffic of a real-time audio streaming application
  • Limiting the rate at which a user can send email messages

 

b.Explain leaky bucket and token bucket algorithm..

The UDP frame format is a simple and efficient format for transmitting data over a network. It consists of four fields:

Source port: This field identifies the port number of the sending application.
Destination port: This field identifies the port number of the receiving application.
Length: This field specifies the length of the UDP header and the UDP data.
Checksum: This field is used to verify the integrity of the UDP header and data.

The source port and destination port fields are each 16 bits long. The length field is also 16 bits long, but it specifies the length in bytes of the entire UDP frame, including the header and data. The checksum field is also 16 bits long, and it is calculated using a simple algorithm.

The UDP frame format is very simple, but it is also very efficient. It uses a minimal amount of overhead to transmit data over a network. This makes UDP a good choice for applications that need to transmit data quickly and efficiently, such as online gaming and real-time video streaming.

Here are some examples of applications that use UDP:

  • Online gaming
  • Real-time video streaming
  • Voice over IP (VoIP)
  • DNS
  • TFTP

UDP is a versatile protocol that can be used for a variety of applications. It is a good choice for applications that need to transmit data quickly and efficiently, but it is important to note that UDP does not provide any guarantees of delivery or reliability.

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