Concept of Layering MCQ Quiz - Objective Question with Answer for Concept of Layering - Download Free PDF

The correct answer is: 1) A modem provides internet access, while a NIC manages local area network (LAN) traffic.

Key Differences Between Modem and NIC:

The correct answer is Propagation delay.

Key Points

• In a network, various types of delays can affect the transmission of a packet. These include propagation delay, queuing delay, transmission delay, and processing delay.
• Propagation delay refers to the time it takes for a signal to travel from the sender to the receiver. It is a function of the distance between the two points and the speed of the signal in the medium. If P is the only packet being transmitted and there was no earlier transmission, the propagation delay could be zero if the distance is negligible or if the signal is already at the receiver.
• Queuing delay is the time a packet spends waiting in a queue before it can be transmitted. Since P is the only packet and there were no earlier transmissions, the queuing delay could be zero.
• Transmission delay is the time required to push all the packet's bits onto the link. This delay depends on the packet's length and the transmission rate of the link. Since P is being transmitted, the transmission delay cannot be zero.
• Processing delay is the time it takes for a router or switch to process the packet header and make a forwarding decision. This is typically non-zero as it involves computational steps.

Additional Information

• Propagation delay is determined by the physical medium (e.g., copper wire, fiber optic) and the speed of light or electrical signals in that medium.
• The propagation delay is usually calculated as the distance divided by the speed of the signal. For example, in fiber optics, the speed is approximately 2/3 the speed of light in a vacuum.
• In high-speed networks, propagation delay can become significant, especially over long distances like transcontinental or undersea cables.
• Understanding and minimizing delays is crucial for optimizing network performance and ensuring efficient data transmission.

Explanation:

Multiplexing of Channels

Definition: Multiplexing is a method used in telecommunications to combine multiple signals into one signal over a shared medium. The goal is to maximize the utilization of the medium and to efficiently manage the bandwidth. There are various types of multiplexing, including Time Division Multiplexing (TDM), Frequency Division Multiplexing (FDM), and others, depending on how the signals are combined and transmitted.

Working Principle: When two or more channels are multiplexed, their individual data streams are combined into a single data stream that can be transmitted over a single communication link. This process involves the allocation of the link’s bandwidth to the different channels, either by dividing the time (in TDM) or the frequency (in FDM) among them.

Example: In this specific case, we have two channels with bit rates of 150 Mbps and 300 Mbps respectively. When these two channels are multiplexed, their combined bit rate will be the sum of their individual bit rates.

Calculation:

To determine the bit rate of the link after multiplexing these two channels, we simply add their individual bit rates:

Bit rate of Channel 1 = 150 Mbps

Bit rate of Channel 2 = 300 Mbps

Bit rate of the link after multiplexing = Bit rate of Channel 1 + Bit rate of Channel 2

Bit rate of the link after multiplexing = 150 Mbps + 300 Mbps = 450 Mbps

Correct Option Analysis:

The correct option is:

Option 3: 450 Mbps

This option correctly represents the total bit rate of the link after multiplexing the two channels. The combined bit rate is the sum of the individual bit rates of the channels being multiplexed, which in this case is 150 Mbps + 300 Mbps = 450 Mbps

The correct answer is Transport layer.

Key Points

• The Transport layer is responsible for process-to-process delivery of the entire message.
  • This layer ensures that data is transferred from one process to another reliably and without errors.
  • It manages the establishment, maintenance, and termination of the logical connection between the two communicating hosts.
  • The Transport layer protocols include TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
  • TCP provides reliable, connection-oriented service, ensuring that data is delivered in the correct order and without errors.
  • UDP provides a connectionless service with minimal error recovery features, making it faster but less reliable than TCP.

Additional Information

• The Transport layer also handles flow control, ensuring that a sender does not overwhelm a receiver with too much data at once.It is responsible for multiplexing and demultiplexing of data, meaning it can handle multiple communication streams at the same time.
• The Transport layer can provide error detection and correction mechanisms to ensure data integrity.
• Port numbers are used at the Transport layer to identify different processes or services running on the same device.
• This layer also provides mechanisms for congestion control to manage network traffic and avoid congestion.

 The correct answer is Option 2

Key Points

• ICMP is mainly used for error reporting and diagnostic purposes.
• It is an integral part of the Internet Protocol Suite, used by network devices to send error messages and operational information.
• ICMP messages are typically used for network diagnostics, such as the "ping" command.
• One of the key messages in ICMP is the redirect message, which informs a host that there is a better route available for a particular destination.

Additional Information

• ICMP does not report all errors during transmission. It primarily deals with issues like unreachable destinations, routing issues, and network diagnostics.
• ICMP "destination unreachable" messages are used when a packet cannot be delivered to its destination.
• Routers use ICMP to inform hosts of network issues, but it does not handle path correction directly; that is typically the role of routing protocols.

This solution provides the correct information about ICMP and clarifies why option 2 is accurate.

A network hub is a hardware device for connecting multiple devices together and making them act as a single private network segment. It has multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port except the original incoming. A hub works at the physical layer (layer 1) of the OSI model.

The correct answer is Telnet.

Key Points

• Any application that empowers users to remotely access another computer(no matter how far away) is called remote access.
• Telnet is an application protocol that uses a virtual terminal connection to offer bidirectional interactive text-oriented communication over the Internet.
• Telnet facilitates remote login on a computer.
• It also facilitates terminal emulation purposes.
• Telnet was developed in 1969.
• Telnet allows users to execute various application programmes on a distant site and then transport the results back to their local computer.

Additional Information

• The Hypertext Transfer Protocol (HTTP) is the backbone of the internet's data transfer.
  • It is a stateless protocol.
• Real-Time Protocol (RTP) is a protocol designed to handle real-time traffic (like audio and video) of the Internet.
• File Transfer Protocol is a set of rules that govern how computers transfer files from one system to another over the internet

The correct answer is option 4.

Concept:

The bridge is used to connect similar LANs with the same protocols. A bridge operates at the data link layer. It is also used for interconnecting two LANs working on the same protocol. It has a single input and single output port, thus making it a 2 port device. A bridge must contain addressing and routing capability.

A bridge is a network device that joins two or more LANs (local area networks) to build a larger LAN. Network bridging is the process of aggregating networks. A bridge joins the various components to make them appear as if they are all part of the same network.

Hence the correct answer is Bridges.

Additional Information

• Switches are networking devices that operate at the OSI model's layer 2 or data link layer. They connect network devices and use packet switching to deliver, receive, and forward data packets or data frames across the network. A switch has a number of ports into which computers can be connected.
• A router is a networking device that sends data packets from one computer network to another. On the Internet, routers are in charge of traffic direction. Data packets are used to send data over the internet, such as a web page or an email.
• A gateway is a network node that serves as a connection point between two networks that use distinct transmission protocols.

The Mesh network topology provides the highest fault tolerance of all of the network topologies. By having separate cables for each connection, it allows any one cable to break without interfering with the rest of the network.

Given:

Message size = 2400 bits.

The header of the transport layer = 150 bits.

Segment size at transport layer = (Header + Message size) = 150 + 2400 = 2550 bits.

Maximum, transmission unit at destination network = 900 bits

 So, At a time, data supported by the destination network = 900 – 26 = 874 bits.

Hence, 2550 bits are divided into packets having a maximum of 874 bits. So:

But 874 is not divisible by 8,

So, 

Length of packet 1 = 872 bits.

Length of packet 2 = 872 bits.

Length of packet 3 = 806 bits.

 

 

Total  = 2550 bits.

Network layer packets are transmitted via two networks, each of which uses a 26-bit header. So, The number of bits, including headers delivered to the destination network is:

Packet 1 (Data + Header) size = 26 + 26 + 872 = 924 bits.

Packet 2 (Data + Header) size = 26 + 26 + 872 = 924 bits.

Packet 3 (Data + Header) size = 26 + 26 + 806 = 858 bits.

 Total = 2706 bits. 

The correct answer is Gateway.

Key Points

• A device used to connect two or more different networks is called Gateway.
  • ​It is a network node used in telecommunications that connects two networks with different transmission protocols together.
  • It serves as an entry and exit point for a network as all data must pass through or communicate with the gateway prior to being routed.
  • It is also called as ' Protocol Converter ' because it can convert the data packets as per the destination network protocol requirement.
• Switches
  • ​A network switch forwards data packets between devices.
  • Switches are networking devices operating at layer 2 or a data link layer of the OSI model.
  • Switches can be hardware devices that manage physical networks or software-based virtual devices.
• Repeater
  • ​It operates at physical layer of the OSI model.
  • It is a hardware device that regenerates an incoming signal from the sender before retransmitting it to the receiver.
• Hub
  • ​A network hub is a node that broadcasts data to every computer or Ethernet-based device connected to it.
  •  A hub has many ports in it. They are generally used to connect computers in a LAN.

A media access control address (MAC address) is a unique identifier assigned to a network adaptor for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking technologies, including Ethernet, Wi-Fi, and Bluetooth.

Important Points:

MAC broadcast address (MAC destination) consists of 6 bytes i.e. 48 bits and all are 1’s

MAC broadcast address → FF:FF:FF:FF:FF:FF

Limited broadcast address (IP-32 bit) → 255.255.255.255

The correct answer is option 3.

Concept:

MODEM stands for modulator-demodulator. A modem is a piece of hardware that allows a computer to send and receive data through a phone line, cable, or satellite.

• A modem is a device that sends and receives data through a communication channel like twisted-pair telephone lines, coaxial cables, or optical fibres.
• The modulation technique is used to transform the analogue signal to digital at the source.
• Demodulation is employed at the receiver to transform the digital signal back to the analogue.

Hence the correct answer is Modem.

OSI Model

• OSI stands for Open System Interconnection is 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 inter-computer communications.

There are seven OSI layers. Each layer has different functions. A list of seven layers are given below:

1) 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.

2) 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 reliable and efficient communication between two or more devices.

3) 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 destination based on the network conditions, the priority of service, and other factors.
• Logical Addressing and Routing are functions of the Network Layer.

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.

5) Session Layer:

• The Session layer is used to establish, maintain, and synchronizes the interaction between communicating devices.

​6) Presentation Layer:

• 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.

7) Application Layer: 

• An application layer serves as a window for users and application processes to access network service.
• This layer provides network services to the end-users.
• HTTP is an application layer protocol designed within the framework of the Internet protocol suite. Its definition presumes an underlying and reliable transport layer protocol, and Transmission Control Protocol (TCP) is commonly used.

​Thus, HTTP is an application layer in the OSI Model of Networking.

Key Points

Network layer protocols are,

• IP(Internet Protocol​),
• ARP(Address Resolution Protocol),
• ICMP (Internet Control Message Protocol).

Hence the correct answer is IP.

Additional Information

• SMTP (Simple Mail Transfer Protocol) is an application layer protocol in OSI.
• HyperText Transfer Protocol (HTTP), is the Web's application-layer protocol,
• Transmission Control Protocol (TCP) In terms of the OSI model, TCP is a transport-layer protocol.