Computer Network (CN) All Important Questions and Answers in English (MDSU)

There are 6 main types of addresses in IPv6:

1. Global Unicast – A unique address used on the public internet.
2. Unique Local – For private networks.
3. Link Local – For communication on the local network.
4. Multicast – To send data to more than one device simultaneously.
5. Anycast – To send data to the nearest node.
6. Modified EUI-64 – For auto-configuration.

28. What is Auto-configuration in IPv6?

    With auto-configuration, IPv6-enabled devices do not need a manual IP address. They automatically create their own Link-Local Address and request a Global Address from the network.

29. What is an Anycast Address?

    An anycast address is a special IPv6 address that can be shared by multiple devices, but data is sent only to the nearest device.

30. What is a Wireless LAN (WLAN)?

    A WLAN is a wireless network that connects devices using Wi-Fi. It operates on the IEEE 802.11 standard and does not require physical cables.

31. What is IEEE 802.11?

    IEEE 802.11 is a Wi-Fi Standard that defines data transmission in a wireless network.

32. What is Mobile IP?

    Mobile IP is a networking protocol that allows any device to move from one network to another without changing its IP address.

33. What is Wireless TCP?

    Wireless TCP (Transmission Control Protocol) is used to manage data transmission in wireless networks. It helps to control data loss.

34. What is Bluetooth and how does it work?

    Bluetooth is a short-range wireless communication technology that allows devices to connect and share data. It operates on the 2.4 GHz frequency and creates small networks (piconets).

35. What is NS2 and where is it used?

    NS2 (Network Simulator 2) is a simulation tool used to simulate wired and wireless networks. It is used for network protocols and performance analysis.

36. What is NAM (Network Animator)?

    NAM is a visual tool that graphically shows an NS2 simulation. It allows you to see the movement of packets and network performance.

37. How are NS2 and NAM installed?

    To install NS2 in Linux, these commands are used:

    sudo apt-get update
    sudo apt-get install ns2 nam
    

    After that, ns and nam are tested separately to verify.

38. What are the OTcl and C++ Interfaces in NS2?

    OTcl (Object-oriented Tcl) is used for simulation setup, while C++ defines the core network models.

39. What are Nodes and Agents in NS2?

    Node: A device (computer, router, mobile) in a network is called a node.
    Agent: Agents are used to generate and process data packets.

40. How is a Simple Node created in NS2?

    To create a node in an OTcl script, this command is written:

    set n0 [$ns node]
    set n1 [$ns node]
    

41. What are Trace Files and their Formats?

    In NS2, Trace Files are used to analyze network performance. Common formats:

    • NAM Trace – For graphical animation
    • Text Trace – For debugging and analysis
42. How are External Commands invoked in NS2?

    In NS2, external system commands can be run with the exec function:

    exec ls -l  

43. How are Links created in Wired Networks?

    To create links for wired networks in NS2:

    $ns duplex-link $n0 $n1 2Mb 10ms DropTail
    

    Here, 2Mb is the bandwidth, 10ms is the delay, and DropTail is the queue.

44. How is Traffic generated in NS2?

    To generate traffic in the network:

    set udp [new Agent/UDP]
    $ns attach-agent $n0 $udp
    

45. How are Routing Protocols set in NS2?

    For example, to set the OSPF Routing Protocol, the command in the OTcl script is:

    set ragent [new Agent/rtProto/OSPF]

46. How are Node Positions set in Wireless Networks?

    To set node positions in NS2:

    $node_(0) set X_ 50.0
    $node_(0) set Y_ 100.0
    $node_(0) set Z_ 0.0
    

47. What is a GOD Object?

    The GOD (General Operations Director) object in NS2 manages wireless network simulation and tracks connectivity between nodes.

48. What is a Topography File?

    A topography file contains information about the network's geographic locations and environment, which is loaded into NS2.

49. What are the Wireless Routing Protocols?

    NS2 supports several wireless routing protocols, such as:

    1. DSDV (Destination-Sequenced Distance Vector)
    2. AODV (Ad-hoc On-Demand Distance Vector)
    3. DSR (Dynamic Source Routing)
50. How is a Wireless Scenario created in NS2?

    To create a basic wireless scenario:

    set ns [new Simulator]
    set node1 [$ns node]
    set node2 [$ns node]
    $ns at 1.0 "$node1 setdest 100.0 200.0 10.0"
    

    This will make node1 move at a certain speed.

5 more questions and each answer in 400+ words.

1. What is the OSI Model and explain its Layers in Detail?

Introduction

The OSI (Open Systems Interconnection) Model is a standard model that describes how two devices in a network communicate with each other. It was developed by the ISO (International Organization for Standardization). The OSI model has 7 layers, and each layer has a different function.

The 7 Layers of the OSI Model and their functions:

1. Physical Layer

   • This layer handles the physical transmission media.
   • It includes cables, connectors, voltages, and bit rate.
   • It only transfers bits (0 and 1).

2. Data Link Layer

   • This layer performs error detection and correction.
   • Data is divided into Frames.
   • The MAC Address is in this layer.

3. Network Layer

   • This layer is responsible for the routing of data packets.
   • It involves IP Addressing.
   • IPv4 and IPv6 work in this layer.

4. Transport Layer

   • This layer breaks data into segments.
   • TCP and UDP are in this layer.
   • It performs error control and flow control.

5. Session Layer

   • This layer manages sessions, meaning it establishes, maintains, and terminates the connection between two devices.
   • It can also handle authentication.

6. Presentation Layer

   • This layer encrypts and decrypts data.
   • Data compression and translation also happen here.

7. Application Layer

   • It interacts with the end-user.
   • HTTP, FTP, DNS, SMTP work in this layer.

Conclusion

The OSI Model describes network communication step-by-step, and each layer handles a different functionality. This model is theoretical, but its conceptual importance in networking is very high.

2. What is the difference between IPv4 and IPv6?

Introduction

IPv4 and IPv6 are two versions of the Internet Protocol that provide unique addresses to network devices. However, IPv4 has some limitations, which IPv6 has overcome.

Features of IPv4:

1. 32-bit addressing (4 billion addresses)
2. Numeric format (192.168.1.1)
3. Broadcast Communication supported
4. No security features
5. Manual and DHCP-based configuration

Features of IPv6:

1. 128-bit addressing (unlimited addresses)
2. Alphanumeric format (2001:db8::ff00:42:8329)
3. Anycast and Multicast Communication supported
4. Security built-in (IPSec)
5. Auto-configuration supported

Differences in Detail:

Conclusion

IPv6 is a modern and advanced protocol that is much better than IPv4 in terms of security, scalability, and performance. The world is gradually migrating to IPv6.

3. What is the difference between TCP and UDP?

Introduction

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are both major protocols of the Transport Layer. TCP is used for reliable communication, while UDP is used for fast communication.

Features of TCP:

1. Connection-Oriented Protocol
2. Supports Error Checking and Retransmission
3. Slow but Reliable
4. Used in Web Browsing, Email, File Transfer

Features of UDP:

1. Connectionless Protocol
2. No Error Checking, No Retransmission
3. Fast but Unreliable
4. Used in Live Streaming, Gaming, VoIP

Differences in Detail:

Conclusion

TCP and UDP both have their own advantages and disadvantages. If avoiding data loss is important, TCP is the right choice, but for high-speed transmission, UDP is better.

4. What are MAC Protocols in Wireless Networks?

Introduction

In wireless networks, the job of MAC (Medium Access Control) Protocols is to control data transmission.

Main MAC Protocols:

1. CSMA (Carrier Sense Multiple Access)
2. TDMA (Time Division Multiple Access)
3. FDMA (Frequency Division Multiple Access)
4. CDMA (Code Division Multiple Access)

Working of MAC Protocols:

• CSMA – The device first checks the channel and sends data if it is free.
• TDMA – Devices are given time slots.
• FDMA – Devices are given different frequency bands.
• CDMA – Unique codes are used for data transmission.

Conclusion

MAC protocols are used to make wireless communication efficient and collision-free.

5. What is Bluetooth and how does it work?

Introduction

Bluetooth is a short-range wireless technology that allows devices to connect and share data with each other.

Working of Bluetooth:

1. Operates on the 2.4 GHz frequency.
2. Uses a Master-Slave architecture.
3. Can create Piconets and Scatternets.
4. Has security features for Pairing and Authentication.

Applications of Bluetooth:

1. Wireless Headphones and Speakers
2. File Transfer in Smartphones and Laptops
3. IoT Devices Connectivity

Conclusion

Bluetooth is an important part of modern wireless communication and is used in IoT, smart devices, and portable gadgets.