SEE 2074 (2018)
SUBJECT: COMPUTER NETWORK Full Marks: 40
Group 'A' (Attempt any ten questions.) 10x1=10
1. Protocols used in application layer: TELNET, FTP
2. What is the use of hub?
à Hub is used to create small home networks.
It is used for network monitoring.
They are also used in organizations to provide connectivity.
3. Define physical and application layer.
à The physical layer in the OSI Model is the lowest layer and is used for transmitting data in its basic form: bit-level.
The application layer of the seven-layer OSI model is the top layer that approaches protocols for application interaction with the network.
4. Class which contains network id of 8 bits and host id of 24 bits is called class A ip address.
5. A network hub is a node generally used in star topology that broadcasts data to every computer or Ethernet-based device connected to it.
6. Range of class B ip address.
à Class B ip adress ranges From 128.0. x.x to 191.255. x.x.
7. Write the functions of server.
à To hosts, delivers and manages most of the resources and services to be consumed by the client
8. List out any two application area of computer network.
à Two application area of computer network are:
· Home
· Business
9. Define wireless network.
à A wireless network is a computer network that uses wireless data connections between network nodes.
10. Write any two types of network.
à Two types network are:
· Local Area Network
· Metropolitan Area Network
· Wide Area Network
11. Which topology uses central controller device to connect devices?
à Star topology uses central controller device to connect devices.
12. What is bus topology?
à Bus topology is a network topology where each computer and network device is connected to a single cable or backbone.
13. What is subnetting?
à Subnetting is a strategy used to partition a single large physical network into more than one smaller logical sub networks.
14. What is the use of repeater?
à Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction.
15. List out the types of client-server architecture.
à The types of client server architecture are:
· 1-tier client server architecture
· 2-tier client server architecture
· 3-tier client server architecture
16. Which layer provides the services to user in OSI reference model?
à Application layer provides the services to user in OSI reference model.
17. What is communication satellite?
à It is a satellite placed in orbit round the earth in order to relay television, radio, and phone signals. A communication satellite is an artificial satellite that acts as a large repeater in the sky. It receives signals from the source transmitter, amplifies using transponders, and relays them to the receiver.
18. In which layer, frame is used?
à Frame is used in data link layer.
19. What is decryption?
à Decryption is the process of regaining the plain text from cipher text using decryption key.
20. Define network security?
à Network security is the collection of the policies, processes and practices adopted to prevent, detect and monitor unauthorized access, misuse, modification, or denial of a computer network and network-accessible resources.
Group 'B' (Attempt any five questions.) 5x2=10
21. Write any two features of LAN.
à Features of LAN are:
· Network size is limited to a small geographical area, presently to a few kilometers.
· Data transfer rate is generally high.
· The LAN network is generally owned by a single organization.
· Less number of computer can be connected.
· It has low error rates.
22. Explain bus topology with diagram.
à Note copy
23. Mention the types of IP Address.
à The types of IP Address are:
· Private
· Public
· Static
· Dynamic
24. List out any four network connecting devices.
à Network connecting devices are:
· Router
· Switch
· Hub
· Network Interface card
· Bridge
· MODEM
25. Write any two function of physical layer.
à Two function of Physical layer are:
· It provides an interface between devices (like PC’s or computers) and transmission medium.
· Bit rate control: The Physical layer also defines the transmission rate i.e. the number of bits sent 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.
26. What are the disadvantages of coaxial cable? Write any two.
à Disadvantages of coaxial cable are:
· Poor transmission for longer distances.
· Coaxial cable is bulky and heavy.
· It needs to be grounded to limit interference.
· More difficult to work with this cable as it doesn’t bend easily.
27. What are the uses of VPN. Write any two of them
à The uses of VPN are:
· Avoiding ISP tracking.
· Safely using public WI-FI.
· Accessing blocked websites.
· Speed Up online gaming.
Group 'C' (Attempt any five questions.) 5x4=20
28. Write down the features of WAN(2) .
à The features of WAN are:
· Multiple LANs and MANs are connected together in WAN.
· Communication is done through satellite, microwave system, or optical fibers.
· It is not restricted to a geographical locating; it is spreads all over the world.
· Data transmission is slower in comparison to LANs.
· Expensive
29. Compare between star topology and ring topology.
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30. Explain peer to peer network architecture in details.
à Peer to peer is a type of architecture in which nodes are interconnected with each other and share resources with each other without the central controlling server. All computers (Nodes) have equal authority to access data and act as both a client and server. There is no any dedicated server. It is also called workgroup because of the small group of individual computers, who work together. It is good choice for an environment where there are few computers and users, security is not an issue, and centralized control is not needed.
Advantages:
· It is simple and easier to set up
· The overall cost of implementing and managing the network is cheaper.
· If a computer fails to operate, it will not affect others.
· Users can manage their own system, so dedicated system administrator is not required.
· It is more reliable because central dependency is reduced.
Disadvantages:
· Administration of the network is difficult as there is no dedicated server.
· Data security is poor in this architecture.
· Data recovery and backup process are difficult
· It is not appropriate for a large organization having a large number of computers.
31. Draw the diagram of OSI reference model. Describe the functions of session layer and network layer.
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Function 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
Function of Network layer:
· Routing: The network layer determine which route is suitable from source to destination.
· Logical Addressing: In order to identify each device on internetwork uniquely, the network layer defines an addressing scheme. The sender & receiver’s IP addresses are placed in the header by the network layer. Such an address distinguishes each device uniquely and universally.
· Data Fragmentation: It deals with the fragmentation of data.
· Internetworking: It deals with the internetworking between the two different subnets.
32. Differentiate between UTP and STP.
à Difference between UTP and STP
UTP (Unshielded Twisted Pair) | STP ( Shielded Twisted Pair) |
It is most common twisted pair | It is rarely used |
it does not contain an extra covering | It contains an extra metal foil outside plastic cover of each pair |
it cannot carry data signal for longer distance compared to STP | it can carry data signal for longer distance |
it is cheaper | it is expensive |
it has high noise and crosstalk | It has low noise and crosstalk |
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33. Explain different types of firewall.
à Firewall is a network security system that analyzes and controls the incoming and outgoing network traffics based on the predetermined security rules. Firewalls can be implemented as both hardware and software, or a combination of both. All messages entering or leaving the network pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria. The types of Firewall are:
· Packet Filtering Firewall: Packet-filtering firewalls, the most basic firewall type, examine packets and prevent them from moving on if the specific security rule is not met. This firewall's function is to perform a simple check of all data packets arriving from the network router and inspecting the specifics like source and destination IP address, port number, protocol, and other surface-level data. Packet filtering firewalls don’t open data packets to inspect their contents. Any data packet that fails the simple inspection is dropped. These firewalls are not resource-intensive and have a low impact on system performance. Their main drawback is that they provide only basic protection and are therefore more vulnerable to being bypassed.
· Proxy Firewall: Proxy firewalls acts as an intermediary between server and client. Proxy firewalls filter traffic at the application layer. So, this firewalls are called 'Application-level Gateways'. Unlike basic firewalls, these firewalls transfer requests from clients pretending to be original clients on the web-server. This protects the client's identity and other suspicious information, keeping the network safe from potential attacks. Once the connection is established, the proxy firewall inspects data packets coming from the source. If the contents of the incoming data packet are protected, the proxy firewall transfers it to the client. This approach creates an additional layer of security between the client and many different sources on the network.
· Circuit-level Gateways:
A circuit-level gateway is a type of firewall. Circuit-level gateways work at the session layer of the OSI model, or as a "shim-layer" between the application layer and the transport layer of the TCP/IP stack. They monitor TCP handshaking between packets to determine whether a requested session is legitimate. Like packet-filtering firewalls, these firewalls do not check for actual data, although they inspect information about transactions. Therefore, if a data contains malware, but follows the correct TCP connection, it will pass through the gateway. That is why circuit-level gateways are not considered safe enough to protect our systems
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