Comprehensive Notes on Physical Layer, Digital Transmission, Signals, Media, Line Coding, Transmission Modes, Switching, and Data Link Layer Basics

Quiz 1 Physical Layer Introduction

• Primary Role of the Physical Layer: Interacting with actual hardware and signaling mechanisms.

• Layer Handing Frames to the Physical Layer: Data-link Layer.

• Type of Signals Represented by Voltage Pulses: Digital signals.

• NOT a Type of Transmission Impairment: Compression.

• Cause of Thermal Noise: Heat agitating electronic conductors.

• Transmission Media Using UTP or Fiber Optics: Guided media.

• Channel Capacity Dependence: Bandwidth, error-rate, and encoding.

• Device Combining Data Streams: Multiplexer (MUX).

• Main Purpose of Switching: Forward data between non-directly connected devices.

• Type of Switching: Packet switching.

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Quiz 2 Digital Transmission

• Purpose of Line Coding: Convert digital data into digital signals.

• Line Coding Scheme Using a Single Voltage Level: Unipolar.

• Polar NRZ Encoding (Binary '1'): Positive voltage.

• Problem Solved by Return to Zero (RZ): Clock synchronization between sender and receiver.

• Encoding Scheme Combining RZ and NRZ-L: Manchester.

• Purpose of Block Coding: To ensure accuracy by adding redundant bits.

• Method for Analog-to-Digital Conversion: Pulse Code Modulation (PCM).

• Nyquist Theorem Sampling Rate: At least two times the highest frequency of the signal.

• Serial Transmission: Bits are sent one after another in a queue.

• Disadvantage of Parallel Transmission: High cost due to multiple wires.

Quiz 3 Signals and Transmission Media

• Type of Continuous Signals: Analog signals, represented by electromagnetic waves.

• Transmission Impairment Involving Signal Weakening: Attenuation.

• Main Cause of Intermodulation Noise: Multiple frequencies interfering.

• Example of Guided Media: Fiber optics.

• Primary Characteristic of Unguided Media: No direct connectivity between sender and receiver.

• Channel Capacity Measures: The speed of information transmission.

• Device Separating Multiplexed Data Streams: Demultiplexer (DMUX).

• Advantage of Synchronous Serial Transmission: High speed and no overhead bits.

• NOT a Step in Pulse Code Modulation (PCM): Multiplexing.

• Purpose of Quantization in PCM: To approximate the amplitude of the analog signal.

Quiz 4 Line Coding and Encoding

• Line Coding Scheme Using Three Voltage Levels: Bipolar.

• Manchester Encoding Signal Transition: In the middle of the bit.

• Difference Between NRZ-L and NRZ-I: NRZ-I changes voltage when a '1' is encountered.

• Primary Purpose of Block Coding: To add redundant bits for error detection.

• Type of Polar Encoding: RZ.

• Main Disadvantage of Unipolar Encoding: No rest condition.

• Asynchronous Serial Transmission: Using specific patterns.

• Parallel Transmission: It sends all bits of a group simultaneously.

• Main Advantage of RZ Encoding: Solves clock synchronization issues.

• Step in PCM Involving Converting Sampled Values into Binary: Encoding.

Quiz 5 Transmission Modes and Impairments

• Transmission Mode Sending Bits One After Another: Serial.

• Main Cause of Delay Distortion: Mismatch in signal speed and frequency.

• Noise Type Caused by Irregular Disturbances: Impulse noise.

• Main Advantage of Guided Media Over Unguided Media: Direct connectivity between sender and receiver.

• Synchronous Transmission: By the receiver's timing mechanism.

• Characteristic of Analog Signals: Continuous waveforms.

• Primary Purpose of Multiplexing: To combine multiple data streams into one.

• Switching Type Forwarding Complete Messages: Message switching.

• Main Disadvantage of Impulse Noise: Difficult to eliminate completely.

• NOT a Factor Affecting Channel Capacity: Cable color.

Quiz 6 Transmission Media

• Primary Purpose of Transmission Media: To provide a physical path for communication.

• Example of Magnetic Media: Magnetic tapes.

• Main Advantage of Twisted Pair Cables: Resistance to noise and crosstalk due to twists.

• Connector Used with UTP Cables: RJ45.

• Core Material of a Coaxial Cable: Solid copper conductor.

• PLC Providing Higher Data Rates: Broadband PLC.

• Fiber Optic Technology Transmits Data: Using light rays.

• Difference Between Single-Mode and Multimode Fiber Optics: Single-mode carries a single light beam, while multimode carries multiple.

• NOT a Fiber Optic Connector Type: RJ45.

• Why a Bank Might Use Magnetic Media: To handle huge data backups where internet transfer is impractical.

Quiz 7 Switching Techniques

• Primary Function of Switching: To forward packets from one port to another toward the destination.

• Switching Type Requiring Pre-Established Circuit: Connection-oriented.

• Three Phases of Circuit Switching: Establish, transfer, disconnect.

• Application Suited for Circuit Switching: Voice calls (telephone).

• Major Drawback of Message Switching: Requires large storage on switches for entire messages.

• Packet Switching Improves Efficiency: By breaking messages into smaller packets for multiplexing.

• Advantage of Packet Switching for the Internet: No need for routers.

• Switching Technique Replaced by Packet Switching: Message switching.

• In Packet Switching, What is Added to Each Packet? Header with switching information.

• True About Connectionless Switching: It uses forwarding tables and acknowledgments are optional.

Quiz 8 Data Link Layer Basics

• Primary Responsibility of the Data Link Layer: Converting data streams into signals and managing direct host communication.

• Sub-Layer of the Data Link Layer: Logical Link Control (LLC).

• Purpose of Framing: To encapsulate packets into frames for transmission.

• Data Link Layer Handles Hardware Addressing: Using MAC addresses encoded into hardware.

• Synchronization: Matching clock signals between sender and receiver for accurate data transfer.

• Function of the Data Link Layer that Ensures that data is not lost: Flow Control.

• Role of Error Control: To detect and correct bit errors during transmission.

• Mechanism Helping Multiple Hosts Share a Single Link: CSMA/CD.

• Collision Occurs in a Shared Network Link: The colliding data is retransmitted after a random backoff time.

• NOT a Function of the Data Link Layer: Packet Routing.

Quiz 9 Advanced Data Link Layer

• Sub-Layer Handling Media Access Control: MAC.

• Primary Purpose of the MAC Sub-Layer: To control how devices access shared media.

• Common MAC Protocol for Ethernet Networks: CSMA/CD.

• Data Link Layer Handle a Situation Where a Receiver is Overwhelmed: By using flow control to regulate data transmission.

• Purpose of a MAC Address: To uniquely identify a device on a local network.

• Characteristic of the Logical Link Control (LLC) Sub-Layer: It manages protocols, flow control, and error control.

• Frame Arrives at the Data Link Layer with Errors: The frame is discarded, and the sender is notified.

• Shared Medium Access Method: Ethernet (CSMA/CD).

• Advantage of Using MAC Addresses Over IP Addresses: MAC addresses are globally unique and hardware-based.

• NOT a Responsibility of the Data Link Layer: Logical Addressing (IP).

Quiz 10 Transmission Media and Data Link Layer Integration

• Transmission Medium Immune to Electromagnetic Interference: Fiber Optic Cable.

• Data Link Layer Interact with Physical Transmission Media: By converting frames into electrical/optical signals for transmission.

• Type of UTP Cable Commonly Used: Cat-5e.

• Purpose of the BNC Connector in Coaxial Cables: To terminate the cable.

• Transmission Medium Used for Long-Distance Internet Backbones: Fiber Optic.

• Data Link Layer Ensure Data Integrity: By using error detection and correction mechanisms.

• Disadvantage of Message Switching: Requires large buffer space for entire messages.

• Advantage of Packet Switching over Circuit Switching: Efficient use of network resources through multiplexing.

• Layer Responsible for Converting Data Packets into Frames: Data Link Layer.

• Role of the MT-RJ Connector in Fiber Optic Networks: To connect fiber optic cables.