Data Communications Overview
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Questions and Answers

What does throughput measure in a network?

  • The total number of connected devices
  • The time delay for data packets
  • The capacity of storage devices
  • The average rate of successful data transmission (correct)

What is indicated by high throughput?

  • Good network performance (correct)
  • A lot of packet loss
  • Poor network performance
  • Increased latency

How is network latency commonly measured?

  • In network connections
  • In signal strength
  • In bytes per second
  • In round trips (correct)

Which situation may lead to increased latency in a network?

<p>Network congestion or long distances (C)</p> Signup and view all the answers

What analogy is used to describe the concept of throughput?

<p>The flow of water through a pipe (C)</p> Signup and view all the answers

What effect does high latency have on network services?

<p>Choppy and lagging services (B)</p> Signup and view all the answers

What types of circuits use a single pair of wires to carry signals?

<p>Two-wire circuits (B)</p> Signup and view all the answers

What is one consequence of low throughput in a network?

<p>Potential packet loss (D)</p> Signup and view all the answers

What is a significant disadvantage of bus topology?

<p>Failure of a shared communication line affects all devices. (C)</p> Signup and view all the answers

What type of device can serve as a central hub in star topology?

<p>All of the above (D)</p> Signup and view all the answers

How does the failure of a single host in ring topology impact the network?

<p>It results in the failure of the entire ring. (D)</p> Signup and view all the answers

Which cable type is primarily used in bus topology?

<p>Coaxial cable (A)</p> Signup and view all the answers

In mesh topology, how do hosts connect with one another?

<p>In point-to-point connections (B)</p> Signup and view all the answers

What is a common advantage of star topology over other topologies?

<p>Simplicity in configuration and device connection. (D)</p> Signup and view all the answers

What characterizes the data transmission in bus topology?

<p>Data is sent only one way through the bus. (D)</p> Signup and view all the answers

Which topology requires minimal additional cabling when adding new hosts?

<p>Star topology (D)</p> Signup and view all the answers

What is the primary purpose of data communication?

<p>To transfer data from one place to another (B)</p> Signup and view all the answers

Which of the following is NOT a component of a data communication system?

<p>Transmission Rate (A)</p> Signup and view all the answers

What role does TCP play in data communication?

<p>It divides messages into packets and reassembles them (D)</p> Signup and view all the answers

In a data communication system, what is the function of a protocol?

<p>To ensure data is understandable to the receiver (D)</p> Signup and view all the answers

Which of the following best describes a transmission medium?

<p>A pathway connecting workstations for data transfer (A)</p> Signup and view all the answers

What is the primary function of the Internet Protocol (IP)?

<p>To manage the addressing for data packets (D)</p> Signup and view all the answers

Which statement correctly describes a message in the context of data communication?

<p>Any piece of data intended for transfer, like text or video (D)</p> Signup and view all the answers

When packets arrive at the destination, what does TCP do?

<p>It reassembles the packets in the correct order (B)</p> Signup and view all the answers

In bipolar schemes, what does a zero voltage level represent?

<p>Binary 0 (C)</p> Signup and view all the answers

What is the main difference between synchronous and asynchronous transmission regarding response time?

<p>Synchronous transmission requires completion before response. (D)</p> Signup and view all the answers

Which encoding method in bipolar schemes uses zero voltage to represent bit 1?

<p>Pseudoternary (C)</p> Signup and view all the answers

What is a characteristic of asynchronous transmission?

<p>Random time intervals between transmissions. (C)</p> Signup and view all the answers

How does the cost of synchronous transmission compare to asynchronous transmission?

<p>Synchronous transmission is more costly. (B)</p> Signup and view all the answers

Which of the following states is true for synchronous transmission?

<p>There is no gap present between data. (A)</p> Signup and view all the answers

What do alternating positive and negative voltages represent in the Alternative Mark Inversion (AMI) scheme?

<p>Binary 1 (B)</p> Signup and view all the answers

What is a major drawback of asynchronous transmission compared to synchronous transmission?

<p>Potential empty transmission line during gaps. (D)</p> Signup and view all the answers

Which encoding method defines bit 1 with positive voltage and bit 0 with zero voltage?

<p>Non Return to Zero (NRZ) (D)</p> Signup and view all the answers

In which encoding scheme do signals always transition in the middle of the bit regardless of its value?

<p>Differential Manchester (B)</p> Signup and view all the answers

What is the key characteristic of the Polar NRZ-I encoding scheme?

<p>It has a transition at a boundary for bit 1. (D)</p> Signup and view all the answers

Which data encoding technique is designed to ensure transitions in the signal to represent bit values?

<p>Differential Manchester (C)</p> Signup and view all the answers

Which of the following encoding schemes uses three voltage levels to represent bits?

<p>RZ (A)</p> Signup and view all the answers

What distinguishes Bipolar Encoding from Unipolar Encoding?

<p>Bipolar Encoding has multiple voltage levels. (A)</p> Signup and view all the answers

In the Manchester encoding scheme, what voltage transition occurs for bit 0?

<p>From +V to -V (B)</p> Signup and view all the answers

Which encoding scheme specifies that a binary 1 is mapped to logic-level high?

<p>NRZ-Level (NRZ-L) (D)</p> Signup and view all the answers

What characterizes half-duplex communication in a circuit?

<p>Data transmission occurs in one direction at a time. (C)</p> Signup and view all the answers

What is the primary benefit of using a four-wire circuit?

<p>Reduced interference and increased data transfer rates. (D)</p> Signup and view all the answers

Which components are included in a four-wire circuit?

<p>Transmit Data Positive, Transmit Data Negative, Receive Data Positive, and Receive Data Negative. (B)</p> Signup and view all the answers

What distinguishes circuit switching from packet switching?

<p>Circuit switching establishes a dedicated communication path. (C)</p> Signup and view all the answers

What are the advantages of packet switching?

<p>Increased reliability through rerouting of packets. (D)</p> Signup and view all the answers

In which type of circuit is ground often included?

<p>Four-wire circuits. (A)</p> Signup and view all the answers

What is the purpose of the Transmit Data Negative (TD-) wire in a four-wire circuit?

<p>To carry the negative side of the differential signal for transmitting. (C)</p> Signup and view all the answers

Which of the following statements regarding data transmission methods is inaccurate?

<p>Circuit switching provides fluctuating bandwidth during communication. (A)</p> Signup and view all the answers

Flashcards

Data Communication

The process of transferring data from one location to another.

Data transmission

The process of converting data into signals and transmitting them, then decoding them at the receiving end.

Communication Channels

The medium that connects communication devices.

Message (Data Comm)

The information being sent in data communication, such as a text file or image.

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Sender

The device that sends a data message.

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Receiver

The device that receives a data message.

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Protocol (Data Comm)

A set of rules governing the way data is transmitted and interpreted.

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TCP/IP

A set of protocols that ensures proper packaging, addressing, and reassembly of data during transmission.

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Throughput

The rate of data successfully transmitted and received over a network, typically measured in bits per second (bps).

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Latency

Delay in sending and receiving data packets; the time taken for a data packet to reach its destination after transmission.

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High Throughput

High rate of successful data transmission and reception.

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Low Throughput

Slow rate of successful data transmission and reception.

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High Latency

Large delay in delivering data packets.

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Two-wire Circuit

A circuit using a single pair of wires, one for signal and one for ground.

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Wire Circuit

A circuit that uses physically connected wires to transmit data.

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Network Performance

Overall effectiveness of a network in transmitting and receiving data.

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Bus Topology

A network topology where all devices share a single cable. A failure of any device on the cable does not affect others, but a failure of the cable itself can stop all devices.

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Star Topology

A network topology where all devices connect to a central hub (switch, router). A failure of the hub affects all devices.

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Ring Topology

A network topology where devices are connected in a closed loop. A failure of any device disrupts the entire network.

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Mesh Topology

A network topology where devices can connect to multiple other devices. More direct connections, but more complex than ring or star topologies.

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Single Point of Failure

A system design flaw where one component's failure can cripple the entire network.

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CSMA/CD

A way for devices to share a cable in a bus topology. 'Carrier Sense Multiple Access with Collision Detection'.

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Hub Device

A central device in a star topology that connects all devices on the network.

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Point-to-Point Connection

A direct connection between two devices in a network.

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Half-duplex Communication

Data transmission in one direction at a time, using the same wires for both sending and receiving, but not simultaneously.

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Four-wire Circuit

A circuit using two pairs of wires, one for sending and one for receiving data; often includes ground, but it's not always required.

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Circuit Switching

Establishing a dedicated communication path between two devices for the entire session, maintaining consistent bandwidth and latency.

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Packet Switching

Dividing data into small packets, sending them independently through the network, and reassembling them at the destination.

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TD+

Transmit Data Positive; carries the positive side of the differential signal during transmission in a four-wire circuit.

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TD-

Transmit Data Negative; carries the negative side of the differential signal during transmission in a four-wire circuit.

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Data Encoding Techniques

Methods used to represent data as signals for transmission.

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Differential Signaling

Using pairs of wires to represent data, comparing signal difference, which helps reject noise.

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Amplitude Modulation (AM)

A method of transmitting information by varying the amplitude of a wave.

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Frequency Modulation (FM)

A method of transmitting information by varying the frequency of a wave.

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Non-Return to Zero (NRZ)

A digital encoding scheme where the signal level holds the bit's value for the full duration of the bit period without returning to zero.

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Unipolar encoding

A data encoding method where all signal levels are either positive or negative, with zero representing a bit value.

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Polar encoding

A data encoding method where positive and negative voltages represent the bits.

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Pulse Code Modulation (PCM)

A method of converting an analog signal to a digital signal by sampling and quantizing.

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Return to Zero (RZ)

A type of digital encoding where the signal returns to zero in the middle of each bit period. For example, half positive, half zero, then half negative, half zero.

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Manchester encoding

A data encoding scheme using transitions in the middle of each bit to represent data.

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Bipolar Schemes

A data transmission method using three voltage levels (positive, negative, and zero) to represent binary data. One level represents 0, the other two represent 1's in an alternating pattern.

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AMI (Alternative Mark Inversion)

A bipolar scheme where binary 0 is represented by zero voltage, and 1's by alternating positive and negative voltages.

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Pseudoternary

A bipolar scheme where binary 1 is represented by zero voltage, and 0 is represented by alternating positive and negative voltages.

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Synchronous Transmission

Data transmission method where data is sent in blocks/frames, transmission is faster and more costly, and requires synchronized clocks for proper data interpretation.

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Asynchronous Transmission

Data transmission method where data is sent in bytes/characters, transmission is slower and more economical, and does not need synchronized clocks.

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Transmission Speed (Synchronous)

Data Transmission is faster in synchronous transmission compared to asynchronous transmission.

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Cost of Transmission (Synchronous)

Synchronous transmission is generally more costly than asynchronous transmission due to synchronization requirements.

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Time Interval (Asynchronous)

Time interval of transmission is random in asynchronous transmission

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Study Notes

Data Communications Lecture Notes

  • Data communication is the process of transferring data from one place to another
  • It involves the conversion of data into signals that can be transmitted and then reconverted at the receiving end
  • Data communication systems consist of components:
    • Message: The information to be transmitted
    • Sender: The device that sends the data
    • Receiver: The device that receives the data
    • Communication channels: The medium connecting sender and receiver (e.g., wires, fiber optics)
    • Protocols: Sets of rules that govern how data is transmitted
  • Protocols define how data is transmitted and communicated
  • Communication channels connect multiple workstations
  • Data is often broken into packets and sent over the internet

Data Communication Models

  • OSI model: A conceptual model of network architecture
    • 7 layers: Application, Presentation, Session, Transport, Network, Data Link, and Physical
  • TCP/IP model: A model for internet communication
    • 4 conceptual layers: Application, Transport, Internet, and Network Access

Data Transmission Types

  • Serial Communication: Data transmitted sequentially bit by bit over a single channel
  • Parallel Communication: Data transmitted simultaneously over multiple channels

Communication Channels/Media

  • Wired Media:
    • Twisted Pair Cable: uses twisted copper wires
    • Fiber Optic Cable: uses light signals
    • Coaxial Cable: uses a central copper wire surrounded by insulation and a metal shield to reduce noise
  • Wireless Media:
    • Radio: uses electromagnetic waves at various frequencies (3 kHz to 300 GHz)
    • Microwaves: uses electromagnetic waves for long-distance communication
    • Infrared: uses electromagnetic waves with frequencies below visible light
    • Satellite: used for long-distance communication

Network Topologies

  • Point-to-Point: Two devices connected directly
  • Bus: All devices share a single communication line
  • Star: All devices connect to a central hub
  • Ring: Devices connected in a closed loop
  • Mesh: Multiple connections between devices, can be full (all devices connected to all others) or partial

Transmission Modes

  • Simplex: One-way communication
  • Half-Duplex: Two-way communication, but only one direction at a time
  • Full-Duplex: Two-way communication in both directions simultaneously

Data Encoding Techniques

  • Unipolar, Polar, Bipolar: Represent data as varying voltages, used in data transmissions

Synchronization Methods

  • Synchronous: Fixed time intervals between data transmission
  • Asynchronous: Time intervals vary, using start and stop bits

Errors

  • Errors can be detected and corrected in real time in more efficient systems

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Data Communications PDF

Description

This quiz covers the fundamentals of data communications, including the essential components, protocols, and communication models such as OSI and TCP/IP. It is designed to test your understanding of how data is transmitted and received over various channels. Prepare to delve into the key concepts that underpin modern networking.

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