Introduction to Network and Network Models : SYBCS : Computer Networks 1 : PYQ

 1 mark

Q. Which topology requires a multipoint connection ?

Answer: The topology that requires a multipoint connection is a bus topology.

Q.  Give the diagrammatic representation of Mesh Topology.

Q. Define mesh topology.

Q. Write any two advantages to star topology.

Answer: Advantages of star topology are as follows:

1) Easy to troubleshoot: If there is an issue with one device , it is easy to identify and fix without affecting rest of the network.

2) High performance: Since each device has a dedicated connection to central hub, the network performance is very high.

- -Q. List 4 application Layer Protocol.

Answer: The 4 application layer protocols are:

1) Hypertext Transfer Protocol (HTTP): It is a protocol used to transmit data over the World Wide Web. It is used for communication between web servers and clients, and it enables the transfer of various types of data, such as text, images, videos, and audio.

2) Simple Mail Transfer Protocol (SMTP): It is a protocol used for sending email messages between servers. It defines how email messages are sent and received over the internet, and it is the most commonly used email protocol.

3) File Transfer Protocol (FTP): It is a protocol used for transferring files over the internet. It allows users to upload and download files between computers and servers, and it is commonly used for sharing files between computers on a network.

4) Domain Name System (DNS): It is a protocol used for resolving domain names to IP addresses. It maps human-readable domain names to IP addresses that can be used by computers to connect to web servers and other network resources.

Q. "UDP is Connection Oriented Protocol." State the statement is true / false.

Answer: The statement is False.

UDP (User Datagram Protocol) is a connectionless protocol, which means that it does not establish a dedicated end-to-end connection before transmitting data. 

Q. What is the function of Presentation layer?

Answer: The Presentation layer is the sixth layer of the OSI (Open Systems Interconnection) model, and it is responsible for managing the representation of data exchanged between different systems. The main functions of the Presentation layer include:

Data Translation: It ensures that data transmitted from one system can be read and understood by another system, regardless of the data representation used by each system. It translates data from one format to another as necessary.

Data Compression: It compresses data to reduce the amount of data that needs to be transmitted over the network, which can improve network performance and reduce costs.

Data Encryption: It encrypts data to provide confidentiality and integrity during transmission, ensuring that data is protected from unauthorized access or tampering.

Data Formatting: It formats data to ensure that it can be properly displayed or printed by the recipient system, including things like font size, color, and layout.

--Q. What is Protocol? with its key elements.

Answer: A protocol is a set of rules and procedures that governs the communication between different systems or devices. In the context of computer networking, a protocol defines how data is transmitted over a network and how devices should interact with each other.

The key elements of a protocol include:

Syntax: This refers to the structure or format of the data that is transmitted. It includes details such as the data type, message length, and how data is organized within a message.

Semantics: This refers to the meaning of the data that is transmitted. It defines how the data should be interpreted and processed by the recipient system.

Timing: This refers to the sequencing of messages and how devices should respond to messages sent by other devices. It defines how long a device should wait before resending a message if it does not receive a response from the recipient system.

Error Control: This refers to how errors in data transmission are detected and corrected. It includes techniques such as checksums and acknowledgments to ensure that data is transmitted accurately.

Flow Control: This refers to how devices regulate the flow of data between systems to prevent overloading of the network. It includes techniques such as buffering, throttling, and congestion control to ensure that data is transmitted at an optimal rate.

--Q. Which devices operates at physical layer.

Answer: The Physical layer is the first layer of the OSI (Open Systems Interconnection) model, and it is responsible for transmitting raw bitstream data over a physical communication channel. 

The devices that operate at the Physical layer include:

Network Interface Cards (NICs): These are hardware devices that are installed in computers and other network-enabled devices. They provide the physical interface between the device and the network medium, such as an Ethernet cable or wireless signal.

Hubs: These are simple network devices that receive data from one device and broadcast it to all other devices connected to the hub. They are used to extend the physical reach of a network by providing additional ports for devices to connect to.

Repeaters: These are network devices that amplify and regenerate signals that have weakened over a long distance. They are used to extend the reach of a network by boosting the signal strength of a network transmission.

Cables: Various types of cables are used to transmit data over a physical medium, such as copper cables, fiber-optic cables, or coaxial cables.

Connectors: Various types of connectors are used to physically connect cables to devices or other cables, such as RJ45 connectors, BNC connectors, or ST connectors.

-Q. Write disadvantages of star topology.

Answer: The disadvantages of star topology are:

Single point of failure: The central hub or switch in a star topology is a single point of failure. If the hub or switch fails, the entire network becomes inaccessible.

Cost: Setting up a star topology requires more cabling and networking equipment than some other topologies, such as a bus or ring topology. This can result in higher costs, particularly for larger networks.

Limited scalability: As the number of nodes in a star topology increases, the network can become congested, which can lead to performance issues. Additionally, adding more nodes to the network may require additional cabling and networking equipment, which can be costly and time-consuming.

Dependency on hub or switch: All communication in a star topology is mediated by the central hub or switch, which can result in performance issues if the hub or switch is not able to handle the traffic demands of the network.

Limited distance: The distance between the central hub or switch and the nodes in the network is limited by the length of the cables used. This can make it difficult to set up star topologies for larger physical areas, such as campuses or cities.

Q. For n devices in a network, what is the number of cables required for ring topology.

Answer: In a ring topology, each device is connected to two other devices in a circular manner, forming a ring. For n devices in a network, the number of cables required for a ring topology can be calculated as follows:

Each device needs two cables to connect to the adjacent devices in the ring.

Therefore, the total number of cables required for n devices in a ring topology can be calculated as:

Total number of cables = 2 x n

4 mark

-Q.  Explain star topology with their advantages.

Answer: Star topology is a network topology in which all the devices in the network are connected to a central hub or switch. In a star topology, all communication between devices flows through the hub or switch, which acts as a central point of control.

Some of the advantages of the star topology are:

Easy to manage: Star topology is easy to set up and manage, as each device only needs to be connected to the central hub or switch. This makes it easier to add or remove devices from the network as needed.

Reliable: Since each device in a star topology is connected directly to the central hub or switch, there are no shared communication channels. This reduces the likelihood of collisions and improves the overall reliability of the network.

Scalable: Star topology is highly scalable, as additional devices can be easily added to the network by connecting them to the central hub or switch. This makes it a good choice for networks that need to grow and expand over time.

Easy to troubleshoot: In a star topology, if a device fails, it can be easily isolated and replaced without affecting the rest of the network. This makes it easy to troubleshoot problems and maintain the network.

Higher performance: Star topology can offer higher performance compared to other topologies, such as bus topology, because each device has a dedicated connection to the central hub or switch. This means that the network is less likely to become congested, and data can be transmitted more quickly.

Q. What are the responsibilities of session and presentation layer ?

Answer: The Session layer and Presentation layer are two of the seven layers in the OSI (Open Systems Interconnection) model, which is a conceptual framework that describes how information is transmitted between different devices in a network.

The responsibilities of Session layer are:

Establishing, maintaining and terminating sessions between applications: The session layer is responsible for setting up and maintaining sessions between applications that need to communicate with each other. It also terminates the session when communication is complete.

Synchronization: The session layer ensures that data transmitted between applications is synchronized, so that the receiver can interpret the data correctly.

Checkpointing and recovery: The session layer is responsible for checkpointing and recovery mechanisms that allow a session to be resumed after an interruption, such as a network failure.

Session management: The session layer manages sessions by handling issues such as multiple sessions between the same applications, session suspension, and session reconnection.

The responsibilities of Presentation layer are:

Data encoding and decoding: The presentation layer is responsible for encoding data into a format that can be understood by the receiver, and decoding data received from the sender into a format that can be understood by the receiver's application.

Data compression and encryption: The presentation layer is responsible for compressing data to reduce the amount of data that needs to be transmitted, and encrypting data to ensure that it is secure during transmission.

Data formatting and syntax: The presentation layer is responsible for formatting and syntax conversion of data between different systems, so that the data can be interpreted correctly by the receiving application.

Character code translation: The presentation layer converts data from one character code to another, so that data can be transmitted between different systems with different character codes.

Q. State advantages and disadvantages of mesh topology.

Answer: Answer:  Mesh topology is a network design in which every node is connected to every other node. The advantages of this topology include:

High reliability: Because every node has multiple connections, if one link fails, there are alternative paths available for communication.

High scalability: Mesh networks can handle a large number of nodes and can be easily expanded as the network grows.

Security: Mesh networks are more secure than other topologies because there is no single point of failure. Even if one node is compromised, the rest of the network will remain operational.

However, there are also some disadvantages of mesh topology, which include:

High cost: Mesh networks require a large number of cables and network interface cards, which can make them expensive to install and maintain.

High complexity: With so many connections, mesh networks can be difficult to configure and manage.

Low efficiency: With all the nodes connected to every other node, there can be a lot of unnecessary traffic

Q. What is computer Network? Describe any four goals of computer Network.

Answer: Answer:  A computer network is a collection of devices that are connected together to share resources and communicate with each other. The four goals of a computer network are:

Resource sharing: Networks allow multiple devices to share resources such as printers, scanners, and storage devices.

Communication: Networks allow devices to communicate with each other, enabling users to share information and collaborate on projects.

Reliability: Networks can be designed to provide redundancy and failover, ensuring that critical resources remain available even if some network components fail.

Scalability: Networks can be designed to handle large numbers of devices and users, allowing organizations to grow their networks as needed.

Q. What is Topology ? Explain the Ring Topology with advantages and disadvantages.

Answer: A. Topology refers to the physical layout of a network, including how the nodes are connected and how data is transmitted between them. Ring topology is a network design in which each device is connected to the next device in a circular loop.

Advantages of ring topology include:

Reliability: Data flows in one direction, so if one device fails, it does not affect the rest of the network.

Efficient use of resources: In a ring topology, data is transmitted in a controlled sequence, which minimizes collisions and reduces network congestion.

Easy to install and manage: Ring networks are relatively easy to install and manage, making them a good choice for small businesses and home networks.

Disadvantages of ring topology include:

Limited scalability: Ring networks can become congested as the number of devices on the network increases, which can slow down data transmission.

Single point of failure: If the main cable connecting the devices in the ring breaks, the entire network can be brought down.

Difficult to troubleshoot: If there is a problem in the network, it can be difficult to isolate the source of the problem.

Q. Explain hierarchical name space.

Answer: A hierarchical namespace is a naming system in which names are organized in a tree-like structure. In this system, each name represents a unique location in the hierarchy, and the names are used to identify objects or resources in a network. The structure of the hierarchy is typically defined by a set of rules or protocols.

In a hierarchical namespace, the top-level domain names represent the highest level of the hierarchy, such as .com or .org. Each domain can be further divided into subdomains, which are represented by additional levels in the hierarchy. For example, the domain name example.com might have subdomains like sales.example.com or support.example.com.

Hierarchical namespaces are used in many different types of networks, including the Internet, where domain names

Q. Explain TCP/IP Model in detail.

Answer: The TCP/IP model is a protocol stack used for communication over the internet and other networks. It consists of four layers: the application layer, transport layer, internet layer, and network access layer.

Application layer: This layer is responsible for providing network services to applications. It includes protocols such as HTTP, FTP, SMTP, and Telnet.

Transport layer: This layer is responsible for the reliable delivery of data between devices. It includes protocols such as TCP and UDP.

Internet layer: This layer is responsible for the routing of data between networks. It includes the IP protocol.

Network access layer: This layer is responsible for the transmission of data between devices on the same network. It includes protocols such as Ethernet and Wi-Fi.

Q. State four levels of addresses used in TCP/IP.

Answer: The four levels of addresses used in TCP/IP are:

Physical address: This is the unique hardware address assigned to each device on a network, such as a MAC address.

IP address: This is a unique numerical address assigned to each device on a network that allows it to communicate with other devices on the internet.

Port address: This is a numerical address that identifies a specific application or service running on a device.

Domain name: This is a human-readable name that maps to an IP address and is used to access resources on the internet.

Q. Using diagram, write the protocol stack of TCP/IP model.

Answer: Here is a diagram of the TCP/IP model protocol stack, from the top to bottom:

Application layer: HTTP, FTP, SMTP, Telnet, DNS, etc.

Transport layer: TCP, UDP

Internet layer: IP

Network access layer: Ethernet, Wi-Fi, etc.

Q. Compare and contrast OSI and TCP/IP model.

Answer: The OSI and TCP/IP models are both protocol stacks used for communication over networks. However, there are some key differences between them:

Layers: The OSI model has seven layers, while the TCP/IP model has four layers.

Complexity: The OSI model is more complex and detailed, with each layer having a specific function and set of protocols. The TCP/IP model is more streamlined and efficient, with some layers combining functions.

Adoption: The TCP/IP model is more widely adopted and used in practice, while the OSI model is more of a theoretical model.

Compatibility: The TCP/IP model is backward compatible with the older protocols used on the internet, while the OSI model is not.

Q. Explain OSI reference model in detail.

Answer: The OSI (Open Systems Interconnection) reference model is a theoretical model that describes the functions and interactions of communication systems. It consists of seven layers, each with a specific function:

Physical layer: This layer defines the physical characteristics of the communication medium, such as electrical and mechanical specifications.

Data link layer: This layer provides error-free transmission of data between devices on the same network.

Network layer: This layer provides routing and addressing services for data transmission between different networks.

Transport layer: This layer provides reliable end-to-end data delivery between applications.

Session layer: This layer manages the communication sessions between applications.

Presentation layer: This layer translates data into a format that can be understood by the application.

Application layer: This layer provides network services to applications, such as email, file transfer, and remote login.

-Q. Explain the similarities and differences between OSI and TCP/ IP reference model.

Answer: The OSI (Open Systems Interconnection) and TCP/IP (Transmission Control Protocol/Internet Protocol) reference models are two different models used for understanding the functions and interactions of communication systems. Here are some similarities and differences between the two models:

Similarities:

Both models have a layered architecture that defines the functions and services required for communication between devices on a network.

Both models provide a framework for the development of network protocols.

Both models include layers for handling data at different levels of abstraction.

Differences:

Sr.No.	OSI	TCP/IP
1	Represents open system interconnection.	Represents the Transmission Control Protocol / Internet Protocol.
2	OSI is a generic, protocol independent standard.	TCP/IP model depends on standard protocols about which the computer network has created.
3	It provides quality services.	It does not provide quality services.
4	It is difficult as distinguished to TCP/IP.	It is simpler than OSI.
5	It uses a horizontal approach.	It uses a vertical approach.