SEE 2073
Group A
1. What is computer network?
à Computer network is the group of two or more computing device linked together for the purpose of communicating, sharing information and hardware resources.
2. What is network topology?
à Network topology is the description of the physical arrangement and connection pattern of each device connected in the network.
3. What is switch?
à A network switch (also called switching hub, bridging hub, and, by the IEEE, MAC bridge) is networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destination device.
4. Write the full form of OSI reference model.
à The full form of OSI reference model is Open System interconnection model.
5. Define unguided media.
à The communication channel in which data are transmitted through waves instead of wires are called unguided media.
Group B
6. Define Home network.
à Home network is a type of computer network that facilitates communication among the devices within the close vicinity of a home.
7. Define internetwork.
à Internetwork can be defined as the system of interconnected networks. Internet is an example of it. (The system in which two or more networks are connected by using intermediary devices such as router or gateway devices is called internetwork)
8. Explain star topology with diagram in short.
à Note
9. Write the types of HUB.
à The types of HUB are:
· Passive HUB
· Active HUB
· Intelligent HUB
10. Differentiate between router and repeater.
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Router | Repeater |
Router joins two completely different networks. | Repeater joins two segment of same network, you can say it extends a network. |
Router makes packet forwarding decision based on source and destination address of a packet, by looking at its route table. | Repeater does boosting/amplification of signals so that it can travel longer distance. |
Router can work on different types of transmission media. | Repeater in general works on unguided media. |
11. List out Layers of OSI model.
à The layers of OSI model are:
· Application Layer
· Presentation Layer
· Session Layer
· Transport Layer
· Network Layer
· Data link Layer
· Physical Layer
12. What are the TCP and UPD?
à TCP stands for transmission control protocol which is a connection oriented protocol whereas UDP stands for User Datagram Protocol which is a connectionless protocol.
13. For what purpose OSI reference model is used?
à OSI reference model is used for the following reasons:
· To guide technology vendors and developers so the digital communications products and software programs they create can interoperate.
· To promote a clear framework that describes the functions of a networking or telecommunications system that's in use.
14. What is cryptography? Writes its types.
à Cryptography is technique of securing information and communications through use of codes so that only those person for whom the information is intended can understand it and process it.
Its types are:
· Symmetric Key Cryptography (Private/Secret Key Cryptography)
· Asymmetric Key Cryptography (Public Key Cryptography)
· Hash Function
15. Where are VPNs used?
à VPN are used in following application:
· Avoiding ISP tracking.
· Safely using public WI-FI.
· Accessing blocked websites.
· Speeding Up online gaming.
16. What is digital signature?
à Digital signature is a mathematical technique used to validate (confirm) the authenticity and integrity of message, digital document.
Group C
17. Explain the business application of computer network.
à Note (after past question)
18. Differentiate between MAN and WAN.
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MAN | WAN |
Stands for Metropolitan Area Network | Stands for Wide Area Network |
It covers smaller geographical area than WAN. | It covers larger geographical area than MAN |
It connects less number of computers | It connects more number of computer |
It has high data transmission rate. | It has low data transmission rate |
Comparatively easier to design and maintain | Difficult to design and maintain |
19. Explain ring topology with its features.
à Note
Features:
· All data flows in only one direction.
· Failure of one node affects the whole network.
20. Write the functions of physical layer.
à The functions of Physical layer are:
· It provides an interface between devices (like PC’s or computers) and transmission medium.
· Bit rate control: Physical Layer maintains the data rate i.e. no. bits a sender can send per second.
· Bit Synchronization: It performs Synchronization of bits. (Maintain data integrity.)
· Transmission mode: It defines direction of data transmission between the devices; simplex, half duplex, full duplex.
· Physical Topologies: It deals with physical topologies.
21. Describe optical fiber with neat and clean diagram.
à An optical fiber is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit data in form of light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data transfer rates) than electrical cables. Fibers are used in.stead of metal wires because signals travel along them with less loss; in addition, fibers are immune to electromagnetic interference, a problem from which metal wires suffer.
Optical fibers typically include a core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fiber to act as a waveguide. In practical fibers, the cladding is usually coated with a tough resin coating and an additional buffer layer, which may be further surrounded by a jacket layer, usually plastic. These layers add strength to the fiber but do not contribute to its optical wave guide properties.
Advantages:
· Higher bandwidth.
· Less signal attenuation: Fiber-optic transmission distance is significantly greater than that of other guided media. A signal can run for 50 km without requiring regeneration. We need repeaters every 5 km for coaxial or twisted-pair cable.
· Immunity to electromagnetic interference: Electromagnetic noise cannot affect fiber-optic cables.
· Resistance to corrosive materials: Glass is more resistant to corrosive materials than copper.
· Light weight: Fiber-optic cables are much lighter than copper cables.
· Greater immunity to tapping: Fiber-optic cables are more immune to tapping than copper cables. Copper cables create antenna effects that can easily be tapped
Disadvantages:
· More Expensive than Electric Wires.
· Difficult to install
· Skilled technical manpower is required to install and are rare
22. Write short note on:
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a. Presentation Layer
In the seven-layer OSI model of computer networking, the presentation layer is layer 6 and serves as the data translator for the network.
Main functions of Presentation Layer are:
· Translation: The processes in two systems exchange the information in the form of character strings, numbers and so on. Different computers use different encoding methods, the presentation layer handles the interoperability between the different encoding methods. It converts the data from sender-dependent format into a common format and changes the common format into receiver-dependent format at the receiving end.
· Encryption/Decryption: the presentation layer encrypts the data at the sender's end and decrypts at the receiver's end.
· Compression: It reduces the number of bits that need to be transmitted on the network.
b. Session Layer:
In the seven-layer OSI model of computer networking, the session layer is layer 5.
Main functions of Session layer are:
· Synchronization: It adds synchronization points or checkpoints in data streams for long communications. This ensures that data streams up to the checkpoints are successfully received and acknowledged. In case of any failures, only the streams after the checkpoints have to be re-transmitted.
· Dialog controller: It allows the systems to communicate in either half-duplex or full-duplex mode of communication.
· Session establishment, maintenance, and Termination: This layer basically provides a mechanism of opening, closing and managing a session between the end-user application processes.
· This layer is also responsible for token management, through which it prevents two users to simultaneously access or attempting the same critical operation
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