CCNA 1 v7 – 4.7.4 Module 4 Quiz – Physical Layer Answers 100% 2025

CCNA 1 v7 – 4.7.4 Module 4 Quiz – Physical Layer Answers 100% 2025

CCNA 1 v7 – 4.7.4 Module 4 Quiz – Physical Layer Answers 100% 2025

The Physical Layer of the OSI model is fundamental for enabling data transmission across network mediums. This layer is responsible for the actual movement of bits in the form of electrical signals, light pulses, or radio waves. It governs the hardware elements such as cables, connectors, and network interface cards (NICs), as well as signaling standards and synchronization. Understanding the principles of the Physical Layer is essential for network professionals, as it directly impacts the reliability and efficiency of data communication. Below are the 100% accurate answers for the “4.7.4 Module Quiz – Physical Layer,” covering key concepts and scenarios for 2025.

  1. A network administrator is troubleshooting connectivity issues on a server. Using a tester, the administrator notices that the signals generated by the server NIC are distorted and not usable. In which layer of the OSI model is the error categorized?

    • Presentation layer
    • Network layer
    • Physical layer
    • Data link layer
      Explanation & Hint:

      The error is categorized in the Physical layer (Layer 1) of the OSI model. The Physical layer is responsible for the transmission and reception of raw bit streams over a physical medium, which includes the generation of electrical, optical, or radio signals by the Network Interface Card (NIC). When the signals generated by the NIC are distorted or unusable, the issue lies in the encoding or transmission of these signals.

      In this scenario, the NIC takes frames from the Data Link layer (Layer 2) and converts them into signals to transmit over the network medium. If these signals are not correctly generated, it indicates a failure at the Physical layer. Possible causes could include a faulty NIC, damaged cabling, interference, or improperly configured hardware.

      While the NIC has responsibilities in both Layer 1 and Layer 2, this specific issue involves the integrity of the signal itself, which is a direct responsibility of the Physical layer. Troubleshooting at this level involves inspecting the hardware components, such as the NIC and cables, as well as ensuring there are no external factors (e.g., electromagnetic interference) impacting the signal quality.

  2. What type of cable is used to connect a workstation serial port to a Cisco router console port?

    • Crossover
    • Rollover
    • Straight-through
    • Coaxial
      Explanation & Hint:

      The correct answer is Rollover.

      A rollover cable, also known as a console cable, is used to connect a workstation’s serial port to the console port of a Cisco router. This type of cable is specifically designed to allow direct management of network devices like routers and switches via their console interfaces.

      The rollover cable is a type of unshielded twisted-pair (UTP) cable with a unique wiring configuration. Unlike crossover or straight-through cables, the pinout of a rollover cable reverses the wire order at one end, with pin 1 at one connector corresponding to pin 8 at the other connector, pin 2 to pin 7, and so on. This reversed wiring is what distinguishes it as a rollover cable.

      When connecting to a Cisco router’s console port, the rollover cable allows a PC or terminal to communicate with the device for configuration or troubleshooting. The workstation typically uses terminal emulation software (e.g., PuTTY or Tera Term) to interact with the router via a serial connection.

      Other cable types, such as straight-through and crossover, are used for different purposes, like connecting devices within a network. A coaxial cable is not applicable in this scenario, as it is typically used for broadband internet or video signals.

  3. Why are two strands of fiber used for a single fiber optic connection?

    • The two strands allow the data to travel for longer distances without degrading.
    • They prevent crosstalk from causing interference on the connection.
    • They increase the speed at which the data can travel.
    • They allow for full-duplex connectivity.
      Explanation & Hint:

      The correct answer is They allow for full-duplex connectivity.

      In a single fiber optic connection, two strands of fiber are used to enable full-duplex communication, which allows data to be sent and received simultaneously between devices. This setup is essential because light signals in fiber optic cables can only travel in one direction per strand. Therefore, one strand is dedicated to transmitting data (Tx), and the other is used for receiving data (Rx).

      Full-duplex communication is crucial for network efficiency, as it enables continuous, bidirectional data flow without the need for time-sharing or switching between sending and receiving modes. This is especially important in high-speed networks, where delays caused by half-duplex communication could significantly impact performance.

      The other options do not correctly describe the purpose of using two strands of fiber:

      • Longer distances: Fiber optics already support long-distance transmission without significant signal degradation, regardless of the number of strands.
      • Crosstalk prevention: Fiber optic cables are immune to electromagnetic interference, so crosstalk is not an issue.
      • Increased speed: The speed of light signals is determined by the technology of the devices and fiber type, not the number of strands.

      Using two strands ensures an efficient and reliable full-duplex connection for high-speed communication networks.

  4. Which procedure is used to reduce the effect of crosstalk in copper cables?

    • Requiring proper grounding connections
    • Twisting opposing circuit wire pairs together
    • Wrapping the bundle of wires with metallic shielding
    • Designing a cable infrastructure to avoid crosstalk interference
    • Avoiding sharp bends during installation
      Explanation & Hint:

      The correct answer is Twisting opposing circuit wire pairs together.

      Crosstalk in copper cables occurs when the electrical or magnetic fields of a signal in one wire interfere with the signal in an adjacent wire. This interference can degrade the performance of a network by causing data errors and reducing signal clarity. To mitigate this issue, opposing circuit wire pairs within the cable are twisted together.

      Twisting the wire pairs helps cancel out the electromagnetic interference (EMI) generated by the signals on each wire. The twists ensure that the interference from one wire pair is counteracted by the opposite interference from the same pair, effectively minimizing the impact of crosstalk. The tighter the twists, the better the cancellation of crosstalk.

      The other options address different issues but do not directly reduce crosstalk:

      • Proper grounding and metallic shielding are used to counteract EMI and radio frequency interference (RFI).
      • Designing the cable infrastructure avoids external interference but does not reduce internal crosstalk.
      • Avoiding sharp bends prevents physical damage and signal loss but does not affect crosstalk.

      Therefore, the most effective measure to reduce crosstalk specifically is the twisting of wire pairs within the cable.

  5. What is one advantage of using fiber optic cabling rather than copper cabling?

    • It is usually cheaper than copper cabling.
    • It is able to be installed around sharp bends.
    • It is easier to terminate and install than copper cabling.
    • It is able to carry signals much farther than copper cabling.
      Explanation & Hint:

      The correct answer is It is able to carry signals much farther than copper cabling.

      Fiber optic cabling offers a significant advantage over copper cabling in its ability to carry signals over much greater distances without signal degradation. This is because fiber optic cables transmit data using light signals, which experience minimal attenuation compared to the electrical signals used in copper cabling. As a result, fiber optics are ideal for long-distance communication, such as intercity or international connections, and high-speed network backbones.

      The other options are not correct:

      • Cost: Fiber optic cabling is generally more expensive than copper cabling, both in terms of materials and installation costs.
      • Sharp bends: While fiber optic cables are flexible, they are more sensitive to bending than copper cables. Sharp bends can cause signal loss or damage to the fiber.
      • Ease of installation: Copper cabling is typically easier to install and terminate than fiber optic cabling, which requires specialized tools and skills for splicing and connecting.

      In summary, while fiber optic cabling may have higher initial costs and installation complexity, its ability to transmit signals over long distances with high bandwidth and low latency makes it a superior choice for many modern networking applications.

  6. A network administrator is designing a new network infrastructure that includes both wired and wireless connectivity. Under which situation would a wireless connection be recommended?

    • The end-user device only has an Ethernet NIC.
    • The end-user device requires a dedicated connection because of performance requirements.
    • The end-user device needs mobility when connecting to the network.
    • The end-user device area has a high concentration of RFI.
      Explanation & Hint:

      The correct answer is The end-user device needs mobility when connecting to the network.

      Wireless connectivity is ideal for situations where users require mobility. Unlike wired connections, which are fixed to specific locations, wireless networks allow end-user devices such as laptops, tablets, and smartphones to connect to the network while moving freely within the coverage area of the wireless access points. This flexibility is particularly useful in environments like offices, campuses, warehouses, or public spaces where mobility is essential.

      The other options are not suitable for recommending wireless:

      • Ethernet NIC only: Devices with only an Ethernet NIC cannot connect wirelessly unless additional hardware, like a USB wireless adapter, is used.
      • Dedicated connection for performance: For devices with high-performance or low-latency requirements (e.g., servers or video editing systems), a wired Ethernet connection is preferable due to its stability and higher bandwidth.
      • High concentration of RFI: Wireless connections are susceptible to interference from radio frequency interference (RFI). If the environment has significant RFI, such as in industrial settings, wireless performance may be unreliable, making wired connections a better choice.

      In conclusion, wireless networks are the best option when mobility is a priority, enabling users to stay connected without being physically tethered to a network port.

  7. Which type of UTP cable is used to connect a PC to a switch port?

    • Console
    • Rollover
    • Crossover
    • Straight-through
      Explanation & Hint:

      The correct answer is Straight-through.

      A straight-through cable, also known as a patch cable, is used to connect devices that operate on different layers of the OSI model, such as a PC (host) and a switch. This cable type ensures that the transmit (Tx) pins on one device are correctly connected to the receive (Rx) pins on the other, allowing proper communication between the devices.

      In a typical Ethernet setup, straight-through cables are the standard choice for connecting:

      • PCs or hosts to switches
      • Switches to routers
      • Switches to hubs

      The other cable types serve different purposes:

      • Rollover cables are proprietary cables used to connect a PC to the console port of a router or switch for management purposes.
      • Crossover cables are used to connect similar devices, such as two switches, two PCs, or two routers, without the need for an intermediate device like a switch. Crossover cables reverse the transmit and receive pin assignments on one end to enable direct communication.
      • Console cables are specific to accessing the console port of network devices and are not used for regular data connections.

      In summary, when connecting a PC to a switch port, a straight-through cable is the correct choice to ensure reliable communication and proper operation.

  8. What is the definition of bandwidth?

    • The speed of bits across the media over a given period of time
    • The speed at which bits travel on the network
    • The amount of data that can flow from one place to another in a given amount of time
    • The measure of usable data transferred over a given period of time
      Explanation & Hint:

      The correct answer is The amount of data that can flow from one place to another in a given amount of time.

      Bandwidth is a measurement of the capacity of a network medium to carry data. It represents the maximum amount of data that can flow between two points on a network over a specific period of time, usually measured in bits per second (bps), kilobits per second (Kbps), megabits per second (Mbps), or gigabits per second (Gbps).

      Bandwidth does not refer to the speed at which individual bits travel through the network (which is determined by the physical medium and technology) but rather the volume of data that can be transmitted simultaneously. For example, a 1 Gbps connection can transmit up to 1 billion bits per second under optimal conditions.

      The other options are incorrect:

      • Speed of bits across the media: This describes latency or propagation delay, not bandwidth.
      • Speed at which bits travel: This refers to signal speed, which is unrelated to data capacity.
      • Usable data transferred: This describes throughput, which is the actual data transmission rate, often lower than the theoretical bandwidth due to network overhead.

      In conclusion, bandwidth defines the data transfer capacity of a network medium, impacting the potential performance and efficiency of a network.

  9. Which statement correctly describes frame encoding?

    • It uses the characteristic of one wave to modify another wave.
    • It transmits data signals along with a clock signal which occurs at evenly spaced time durations.
    • It generates the electrical, optical, or wireless signals that represent the binary numbers of the frame.
    • It converts bits into a predefined code in order to provide a predictable pattern to help distinguish data bits from control bits.
      Explanation & Hint:

      The correct answer is It converts bits into a predefined code in order to provide a predictable pattern to help distinguish data bits from control bits.

      Frame encoding is the process of converting a stream of raw data bits into a structured, predefined code. This encoding ensures that both the sender and receiver can correctly interpret the transmitted data. It provides a predictable pattern that helps distinguish between data bits and control bits, such as those used to identify the start and end of a frame. This process improves data integrity and ensures accurate communication.

      Frame encoding methods often include mechanisms to maintain synchronization between the sender and receiver, detect errors, and define control signals. Common encoding schemes include Manchester encoding, Non-Return to Zero (NRZ), and 8b/10b encoding.

      The other options are incorrect:

      • Modifying one wave with another: This describes modulation, which occurs at the Physical layer, not frame encoding.
      • Transmitting data with a clock signal: This refers to synchronization or clock recovery, not frame encoding.
      • Generating electrical, optical, or wireless signals: This describes signal generation, a function of the Physical layer.

      In summary, frame encoding is crucial for creating a reliable and understandable data transmission process, ensuring that data and control signals are clearly differentiated.

  10. What is a characteristic of UTP cabling?

    • Cancellation
    • Cladding
    • Immunity to electrical hazards
    • Woven copper braid or metallic foil
      Explanation & Hint:

      The correct answer is Cancellation.

      Unshielded Twisted Pair (UTP) cabling is a type of copper cabling commonly used in Ethernet networks. A key characteristic of UTP cabling is cancellation, which is achieved through the twisting of paired wires within the cable. By twisting the wires together, the electromagnetic interference (EMI) generated by the current in one wire is canceled out by the EMI from the opposing wire. This significantly reduces crosstalk (interference between adjacent pairs) and external interference from surrounding electronic devices.

      The other options are incorrect:

      • Cladding: This term applies to fiber optic cables, where cladding surrounds the core to reflect light and maintain the signal within the core.
      • Immunity to electrical hazards: UTP cables are not immune to electrical hazards, such as power surges or lightning strikes. Shielded cabling or fiber optics is better suited for environments with significant electrical interference or hazards.
      • Woven copper braid or metallic foil: This describes shielded cables, such as Shielded Twisted Pair (STP) or coaxial cables, not UTP. UTP cables lack additional shielding, which makes them lighter, more flexible, and cost-effective.

      In conclusion, the defining feature of UTP cabling is cancellation, which minimizes interference and enhances signal quality without the need for additional shielding.

  11. A wireless LAN is being deployed inside the new one room office that is occupied by the park ranger. The office is located at the highest part of the national park. After network testing is complete, the technicians report that the wireless LAN signal is occasionally affected by some type of interference. What is a possible cause of the signal distortion?

    • The microwave oven
    • The large number of trees that surround the office
    • The elevated location where the wireless LAN was installed
    • The number of wireless devices that are used in the wireless LAN
      Explanation & Hint:

      The correct answer is The microwave oven.

      Microwave ovens can cause interference with a wireless LAN because they operate at frequencies around 2.4 GHz, which is within the same range as many Wi-Fi networks using the 802.11b/g/n standards. This overlap can result in signal distortion and degraded wireless performance, especially when the microwave is in use. The interference occurs due to the emission of electromagnetic waves from the microwave oven, which disrupt the Wi-Fi signals.

      The other options are incorrect:

      • Large number of trees: Trees do not typically interfere with wireless signals in a one-room office scenario. Dense foliage can absorb or reflect radio waves over longer distances but is not relevant here.
      • Elevated location: The elevation of the wireless LAN installation does not negatively affect the signal. In fact, an elevated location often enhances coverage.
      • Number of wireless devices: In a small, isolated one-room office, the number of wireless devices is unlikely to be high enough to cause significant interference.

      In summary, the likely cause of occasional interference in this scenario is the operation of a microwave oven, which emits electromagnetic signals that can disrupt Wi-Fi connectivity on the 2.4 GHz frequency band. Adjusting the channel or moving the router and microwave apart may help reduce interference.

  12. What is the purpose of the OSI physical layer?

    • Controlling access to media
    • Transmitting bits across the local media
    • Performing error detection on received frames
    • Exchanging frames between nodes over physical network media
      Explanation & Hint:

      The correct answer is Transmitting bits across the local media.

      The purpose of the Physical layer (Layer 1) of the OSI model is to handle the transmission and reception of raw bitstreams over a physical medium. This layer defines the electrical, optical, or radio signal characteristics, as well as the physical properties of cables, connectors, and interfaces, to ensure that bits (0s and 1s) are accurately transmitted and received between devices.

      Functions of the Physical layer include:

      • Encoding data into signals for transmission across the medium.
      • Specifying voltage levels, timing, and synchronization of signals.
      • Determining the physical topology and physical connection standards.
      • Handling medium-specific transmission methods (e.g., optical, electrical, or wireless signals).

      The other options pertain to the Data Link layer (Layer 2):

      • Controlling access to media: Media Access Control (MAC) is a function of the Data Link layer, ensuring orderly access to the shared medium.
      • Performing error detection: Error detection is handled at the Data Link layer to ensure frame integrity.
      • Exchanging frames between nodes: Frame transmission is also a responsibility of the Data Link layer, as it encapsulates and manages data packets.

      In summary, the Physical layer is dedicated to the actual movement of bits across the network medium, forming the foundation for higher-layer operations.

  13. Which characteristic describes crosstalk?

    • The distortion of the network signal from fluorescent lighting
    • The distortion of the transmitted messages from signals carried in adjacent wires
    • The weakening of the network signal over long cable lengths
    • The loss of wireless signal over excessive distance from the access point
      Explanation & Hint:

      The correct answer is The distortion of the transmitted messages from signals carried in adjacent wires.

      Crosstalk occurs when the electrical or magnetic fields of a signal on one wire interfere with the signal on an adjacent wire within the same cable. This interference can distort the transmitted messages, leading to data corruption or reduced network performance. Crosstalk is a common issue in copper cabling, especially in environments where multiple signals are transmitted over tightly packed wires.

      Crosstalk is minimized through the use of twisted pair cabling, such as in Unshielded Twisted Pair (UTP) cables, where the twisting of wires reduces the electromagnetic interference between them.

      The other options describe different phenomena:

      • Distortion from fluorescent lighting: This is caused by electromagnetic interference (EMI), not crosstalk.
      • Weakening of signals over long distances: This is called attenuation, which results in the gradual degradation of signal strength as it travels through the medium.
      • Loss of wireless signals over distance: This is specific to wireless networking and is caused by signal weakening due to excessive distance or obstacles between the device and the access point.

      In summary, crosstalk specifically refers to the interference caused by adjacent wire signals, which can impact the reliability of network communication.

  14. What is indicated by the term throughput?

    • The guaranteed data transfer rate offered by an ISP
    • The capacity of a particular medium to carry data
    • The measure of the usable data transferred across the media
    • The measure of the bits transferred across the media over a given period of time
    • The time it takes for a message to get from sender to receiver
      Explanation & Hint:

      The correct answer is The measure of the bits transferred across the media over a given period of time.

      Throughput refers to the actual rate at which data is successfully transferred across a network medium over a given period of time. It is a practical measurement that includes all transmitted bits, such as user data, protocol overhead, acknowledgments, and encapsulation. Unlike the theoretical bandwidth of a medium (its maximum capacity), throughput reflects the real-world performance of a network and can be influenced by factors such as electromagnetic interference (EMI), network congestion, and latency.

      Key characteristics of throughput:

      • It accounts for all bits transferred, not just usable data.
      • It is often lower than the medium’s specified bandwidth due to network inefficiencies.
      • It is a dynamic metric that can vary based on environmental and operational conditions.

      The other options describe related but distinct concepts:

      • Guaranteed data transfer rate: This is often a service-level agreement (SLA) metric provided by ISPs.
      • Capacity of the medium: This refers to bandwidth, which is the maximum theoretical data transfer rate.
      • Usable data transferred: This is known as goodput.
      • Message transmission time: This refers to latency.

      In conclusion, throughput measures the actual bits transferred, providing a realistic view of network performance.

  15. Which standards organization oversees development of wireless LAN standards?

    • IANA
    • IEEE
    • ISO
    • TIA
      Explanation & Hint:

      The correct answer is IEEE.

      The Institute of Electrical and Electronics Engineers (IEEE) oversees the development of standards for wireless LANs (WLANs) through its 802.11 family of standards. The IEEE 802.11 standards define specifications for wireless networking, including the frequency bands, data rates, modulation techniques, and security protocols used in Wi-Fi networks.

      Key aspects of IEEE’s involvement:

      • 802.11 Standards: These govern wireless LANs and include various amendments such as 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, and 802.11ax (Wi-Fi 6).
      • Global Impact: IEEE standards are widely adopted worldwide, ensuring interoperability and consistency in wireless technologies.

      The other organizations focus on different areas:

      • IANA: The Internet Assigned Numbers Authority manages IP address allocation, domain names, and other internet protocol resources.
      • ISO: The International Organization for Standardization develops broad international standards, including the OSI model, but does not focus on wireless LANs specifically.
      • TIA: The Telecommunications Industry Association develops standards for telecommunications and cabling, not wireless networking.

      In summary, the IEEE is the primary organization responsible for developing and maintaining wireless LAN standards, ensuring reliable and interoperable wireless communication worldwide.