Data Over Cable Service Interface Specification Quiz

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Data Over Cable Service Interface Specification Quiz - Quiz

Data Over Cable Service Interface Specification – or simply DOCSIS – is an international telecommunications standard which permits the addition of high-bandwidth data transfer to an existing cable TV system. What can you tell us about the topic? Let’s find out.


Questions and Answers
  • 1. 

    The first version of the Data Over Cable Service Interface Specification (DOCSIS) was approved as an international standard by what organization? 

    • A.

      The Institute of Electrical and Electronics Engineers (IEEE).

    • B.

      The Society of Cable Telecommunications Engineers (SCTE).

    • C.

      The International Organization for Standardization (ISO).

    • D.

      The International Telecommunication Union (ITU).

    Correct Answer
    D. The International Telecommunication Union (ITU).
    Explanation
    The correct answer is The International Telecommunication Union (ITU). The ITU is a specialized agency of the United Nations that is responsible for coordinating and standardizing telecommunications and information and communication technologies (ICTs) worldwide. It plays a crucial role in developing and approving international standards for various technologies, including data over cable service interface specification (DOCSIS). Therefore, it makes sense that the first version of DOCSIS was approved as an international standard by the ITU.

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  • 2. 

    What layers of the open systems interconnection (OSI) model are applied between Data Over Cable Service Interface Specification (DOCSIS) modems and the cable modem termination system (CMTS)? 

    • A.

      Layers four through seven (Transport Layer, Session Layer, Presentation Layer, and Application Layer) are applied between the DOCSIS modem and CMTS.

    • B.

      Layers one through four (Simple Network Management Protocol, Trivial File Transfer Protocol, Dynamic Host Configuration Protocol, and E-mail) are applied between the DOCSIS modem and CMTS.

    • C.

      Layers four through seven (Physical Layer, Data Link Layer, Network Layer, and Transport Layer) are applied between the DOCSIS modem and CMTS.

    • D.

      Layers one through four (Physical Layer, Data Link Layer, Network Layer, and Transport Layer) are applied between the DOCSIS modem and CMTS.

    Correct Answer
    D. Layers one through four (Physical Layer, Data Link Layer, Network Layer, and Transport Layer) are applied between the DOCSIS modem and CMTS.
    Explanation
    The correct answer is that layers one through four (Physical Layer, Data Link Layer, Network Layer, and Transport Layer) are applied between the DOCSIS modem and CMTS. This means that the communication between the DOCSIS modem and CMTS involves the physical transmission of data, the establishment of a reliable connection, the routing of data packets, and the management of end-to-end communication. These layers are responsible for ensuring that the data is properly transmitted, received, and delivered between the two devices.

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  • 3. 

    Each version of the Data Over Cable Service Interface Specification (DOCSIS) adds features and improvements over the previous version. What features does DOCSIS 2.0 add? 

    • A.

      Increased bandwidth of the upstream and advanced access systems so that higher orders of modulation (and higher data rates) are possible.

    • B.

      Increased bandwidth of the upstream and advanced access systems so that lower orders of modulation (and higher data rates) are possible.

    • C.

      Increased bandwidth of the upstream so that enhanced security and adaptive equalization in the upstream path for improved data throughput are possible.

    • D.

      Increased bandwidth of the downstream with advanced access systems so that higher orders of modulation (and higher data rates) are possible.

    Correct Answer
    A. Increased bandwidth of the upstream and advanced access systems so that higher orders of modulation (and higher data rates) are possible.
    Explanation
    DOCSIS 2.0 adds increased bandwidth to the upstream and advanced access systems, allowing for higher orders of modulation and higher data rates. This means that data can be transmitted at faster speeds and with more efficient use of the available spectrum. This improvement in bandwidth enables better performance and increased capacity for data transmission in the upstream direction.

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  • 4. 

    Of the two sets of protocols, transmission control protocol/Internet protocol (TCP/IP) and simple network management protocol (SNMP), which is used for routing the packets of data over the Internet? 

    • A.

      TCP/IP provides the basic protocol for directing data traffic over the Internet by dividing the data packet into four elements: the packet sequence; the data; the destination address; and the checksum of data.

    • B.

      TCP/IP provides the basic protocol for directing data traffic over the Internet by dividing the data packet into two elements: the data and the destination address.

    • C.

      SNMP provides the basic protocol for directing data traffic over the Internet by dividing the data packet into four elements: the packet sequence; the data; the destination address; and the checksum of data.

    • D.

      SNMP provides the basic protocol for directing data traffic over the Internet by dividing the data packet into two elements: the data and the destination address.

    Correct Answer
    A. TCP/IP provides the basic protocol for directing data traffic over the Internet by dividing the data packet into four elements: the packet sequence; the data; the destination address; and the checksum of data.
    Explanation
    TCP/IP is the correct answer because it is the set of protocols used for routing packets of data over the Internet. It divides the data packet into four elements: the packet sequence, the data, the destination address, and the checksum of data. This division allows for efficient and reliable transmission of data over the network. SNMP, on the other hand, is a different set of protocols used for network management, not for routing data packets.

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  • 5. 

    In a client/server relationship there are two types of client categories: thin clients and thick clients. What is the difference between the two client categories? 

    • A.

      Thin clients are not capable of running applications independent of the server. Thick clients are capable of downloading and running installed applications independent of a server.

    • B.

      Thin clients are small portable devices such as laptop computers and smart phones. Thick clients are stationary devices such as desktop and mainframe computers.

    • C.

      Thin clients will only work with one dedicated server. Thick clients will work with multiple servers simultaneously.

    • D.

      Thin clients are used for home applications such as game consoles or to download movies. Thick clients are used for business applications in computers.

    Correct Answer
    A. Thin clients are not capable of running applications independent of the server. Thick clients are capable of downloading and running installed applications independent of a server.
    Explanation
    Thin clients are client devices that rely on a server to perform most of their processing tasks. They are not capable of running applications independently and require a constant connection to the server to function. On the other hand, thick clients are capable of downloading and running installed applications independently of a server. They have their own processing power and can perform tasks without relying heavily on the server. Thick clients are often used in business settings where more processing power and independence are required.

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  • 6. 

    How do media access control (MAC) protocols increase the efficiency of upstream transmissions from the cable modems?

    • A.

      When an upstream transmission request is received, the MAC protocols instruct the cable modem termination system (CMTS) when to transmit, its bandwidth, and its transmission interval to prevent or decrease the number of upstream packet collisions. The reduction of collisions increases the upstream transmission efficiency since colliding packets need not be resent.

    • B.

      When a downstream transmission request is received, the MAC protocols instruct the cable modem termination system (CMTS) when to transmit, its bandwidth, and its transmission interval to prevent or decrease the number of downstream packet collisions. The reduction of collisions increases the upstream transmission efficiency since colliding packets need not be resent.

    • C.

      When a downstream transmission request is received, the MAC protocols instruct the cable modem when to transmit, its bandwidth, and its transmission interval to prevent or decrease the number of upstream packet collisions. The reduction of collisions increases the upstream transmission efficiency since colliding packets need not be resent.

    • D.

      When an upstream transmission request is received, the MAC protocols instruct the cable modem when to transmit, its bandwidth, and its transmission interval to prevent or decrease the number of upstream packet collisions. The reduction of collisions increases the upstream transmission efficiency since colliding packets need not be resent.

    Correct Answer
    D. When an upstream transmission request is received, the MAC protocols instruct the cable modem when to transmit, its bandwidth, and its transmission interval to prevent or decrease the number of upstream packet collisions. The reduction of collisions increases the upstream transmission efficiency since colliding packets need not be resent.
    Explanation
    MAC protocols increase the efficiency of upstream transmissions from the cable modems by instructing the cable modems when to transmit, its bandwidth, and its transmission interval. This prevents or decreases the number of upstream packet collisions. By reducing collisions, the efficiency of upstream transmission is increased because colliding packets do not need to be resent.

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  • 7. 

    What is channel bonding?

    • A.

      Channel bonding combines the data throughput of a single channel with a number of channels to achieve a maximum data throughput equal to the cumulative total of the bonded channels.

    • B.

      Channel bonding ties the downstream and upstream RF data carriers to fixed frequencies so that the cable modem always knows what frequency to tune to receive downstream data.

    • C.

      Channel bonding combines the data throughput of up to eight adjacent data channels to create a single wide bandwidth data channel to achieve a maximum data throughput equal to the cumulative total of the bonded channels.

    • D.

      Channel bonding ties the downstream cable modem carrier to the out-of-band (00B) data carrier sent to the digital set-top box (STB) to enable the cable modem to receive television signals over the Internet.

    Correct Answer
    A. Channel bonding combines the data throughput of a single channel with a number of channels to achieve a maximum data throughput equal to the cumulative total of the bonded channels.
    Explanation
    Channel bonding is a technique used to increase the data throughput of a network connection by combining multiple channels. By combining the data throughput of a single channel with a number of additional channels, the maximum data throughput can be increased to the cumulative total of all the bonded channels. This allows for faster and more efficient data transmission, improving overall network performance.

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  • 8. 

    How does a cable modem know what frequency and carrier level it should transmit upstream?

    • A.

      When powered on and connected to cable system, the cable modem receives an upstream channel descriptor (UCD) which contains upstream transmission parameters, including frequency and carrier level.

    • B.

      After it is authorized for service, the cable modem receives an upstream channel descriptor (UCD) which contains upstream transmission parameters, including frequency and carrier level.

    • C.

      The installer enters the modem's upstream transmission parameters, including frequency and carrier level, into the modem's configuration file during its activation.

    • D.

      During initialization the cable modem receives upstream transmission parameters, including frequency and carrier level, that were entered for the modem's location in the system.

    Correct Answer
    B. After it is authorized for service, the cable modem receives an upstream channel descriptor (UCD) which contains upstream transmission parameters, including frequency and carrier level.
    Explanation
    The cable modem knows what frequency and carrier level it should transmit upstream after it is authorized for service because it receives an upstream channel descriptor (UCD) which contains the necessary transmission parameters. This UCD is sent to the modem once it is connected to the cable system and powered on.

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  • 9. 

    Why was the Data Over Cable Service Interface Specification (DOCSIS) designed to operate in a shared services environment?

    • A.

      The shared services environment makes optimum use of the network to efficiently transport the continuous data traffic to and from the modems.

    • B.

      The shared services environment follows the same model for television content distribution. Instead of the customer choosing which channel to watch, the cable modem chooses which data packet to receive and then decode.

    • C.

      The shared services environment is a less expensive alternative than dedicated connections, which is most efficient for transporting the intermittent data traffic to and from the modems.

    • D.

      The shared services environment makes optimum use of the network to efficiently transport the intermittent data traffic to and from the modems.

    Correct Answer
    D. The shared services environment makes optimum use of the network to efficiently transport the intermittent data traffic to and from the modems.
    Explanation
    DOCSIS was designed to operate in a shared services environment because it allows for the efficient transportation of intermittent data traffic to and from the modems. This shared services environment optimizes the use of the network, making it a cost-effective alternative to dedicated connections. In this environment, the cable modem selects and decodes the data packets, similar to how television content distribution works. By utilizing the shared services environment, DOCSIS ensures that data traffic is transported efficiently and effectively.

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  • 10. 

    During which part of provisioning is the Data Over Cable Service Interface Specification (DOCSIS) modem authorized for high-speed data service?

    • A.

      Ranging and automatic adjustment.

    • B.

      Characterizing.

    • C.

      Registration

    • D.

      Synchronization of data.

    Correct Answer
    C. Registration
    Explanation
    The DOCSIS modem is authorized for high-speed data service during the registration process. This is when the modem establishes communication with the cable provider's network and provides necessary information such as its unique identifier and capabilities. Registration ensures that the modem is authorized to access the high-speed data service and enables the provider to manage and monitor the modem's usage.

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  • 11. 

    If a customer already has cable television service and is adding high-speed data service, what should be checked on the digital television channels? 

    • A.

      Intermittent operation which is a symptom of noise or interference in the downstream.

    • B.

      Intermittent operation which is a symptom of noise or interference in the upstream.

    • C.

      Buzzing audio and horizontal lines, which become quite obvious on digital channels.

    • D.

      The video and audio carrier levels to make sure that they are on frequency and that their respective levels are 15 dB, plus or minus 2 dB.

    Correct Answer
    A. Intermittent operation which is a symptom of noise or interference in the downstream.
    Explanation
    When a customer adds high-speed data service to their existing cable television service, it is important to check for intermittent operation on the digital television channels. This can be a symptom of noise or interference in the downstream, which may affect the quality of the signal. By identifying and addressing any issues with noise or interference, the customer can ensure a smooth and uninterrupted viewing experience.

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  • 12. 

    In the RF return, what is the relationship between noise, data rate, and bandwidth? 

    • A.

      The lower the bandwidth, the higher the data throughput, the higher the susceptibility to noise.

    • B.

      The higher the bandwidth, the higher the data throughput, the lower the susceptibility to noise.

    • C.

      The higher the bandwidth, the lower the data throughput, the higher the susceptibility to noise.

    • D.

      The higher the bandwidth, the higher the data throughput, the higher the susceptibility to noise.

    Correct Answer
    D. The higher the bandwidth, the higher the data throughput, the higher the susceptibility to noise.
    Explanation
    The relationship between noise, data rate, and bandwidth is that the higher the bandwidth, the higher the data throughput, and consequently, the higher the susceptibility to noise. This means that as the bandwidth increases, more data can be transmitted, but there is also a greater chance for noise to interfere with the signal. Therefore, a higher bandwidth can result in a higher data rate, but it also increases the likelihood of noise affecting the transmission.

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  • 13. 

    Why are maintenance practices for two-way broadband cable systems more complex than for one-way systems? 

    • A.

      Noise funneling the accumulation of noise from different sources, travels downstream from the customer premises to the headend.

    • B.

      Ingress that appears in the upstream frequencies, which is of no consequence in the downstream, must be identified and eliminated.

    • C.

      Ingress that appears in the downstream frequencies, which is of no consequence in the upstream, must be identified and eliminated.

    • D.

      Noise funneling the accumulation of noise from different sources, travels downstream from the headend to the customer premises.

    Correct Answer
    B. Ingress that appears in the upstream frequencies, which is of no consequence in the downstream, must be identified and eliminated.
    Explanation
    In two-way broadband cable systems, there is both upstream and downstream communication. This means that noise and interference can occur in both directions. However, the ingress that appears in the upstream frequencies, which is of no consequence in the downstream, must be identified and eliminated. This adds complexity to the maintenance practices because it requires specific measures to identify and eliminate the ingress in the upstream frequencies without affecting the downstream communication.

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  • 14. 

    Studies of trouble call resolution data show that the majority of ingress/noise in the upstream originates in the customer premises. What can be installed to eliminate or minimize ingress/noise that originates in the customer premises? 

    • A.

      Two-way house amplifiers, window filters, or step attenuators.

    • B.

      High-pass filters, two-way house amplifiers, or step attenuators.

    • C.

      High-pass filters, window filters, or step attenuators.

    • D.

      High-pass filters, window filters, or two-way house amplifiers.

    Correct Answer
    C. High-pass filters, window filters, or step attenuators.
    Explanation
    High-pass filters, window filters, and step attenuators can be installed to eliminate or minimize ingress/noise that originates in the customer premises. These devices are designed to filter out unwanted frequencies and attenuate the signal, reducing the interference caused by ingress/noise.

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  • 15. 

    If a 10 dB step attenuator is installed to reduce the amount of ingress/noise that originates in the customer premises what would be the expected improvement in carrier-to-noise C/N? 

    • A.

      5 dB.

    • B.

      No change.

    • C.

      10 dB.

    • D.

      15 dB.

    Correct Answer
    C. 10 dB.
    Explanation
    Installing a 10 dB step attenuator would result in a 10 dB improvement in carrier-to-noise (C/N) ratio. Attenuators are used to reduce the signal strength, and in this case, it is specifically used to reduce the amount of ingress/noise that originates in the customer premises. By reducing the noise level by 10 dB, the carrier-to-noise ratio improves by the same amount. This means that the carrier signal is now 10 dB stronger compared to the noise, resulting in a better overall signal quality.

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  • 16. 

    Which eight-position, eight-contact (8P8C) modular connector wiring scheme is recommended for residential use? 

    • A.

      ANSI/TIA/EIA-5708.

    • B.

      T568B.

    • C.

      T568A.

    • D.

      Universal Service Order Codes (USOC).

    Correct Answer
    C. T568A.
    Explanation
    The T568A wiring scheme is recommended for residential use. This wiring scheme is commonly used for Ethernet connections and is the most widely used wiring standard. It specifies the arrangement of the eight wires in the connector, ensuring that the connection is made correctly and consistently. The T568A scheme is compatible with most networking equipment and is the preferred choice for residential installations.

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  • 17. 

    What is the preferred connection when connecting the cable modem to the customer's computer? 

    • A.

      Using an unshielded twisted-pair (UTP) cable.

    • B.

      Using a flat silver-satin telephone cable.

    • C.

      Using a shielded twisted-pair (STP) cable.

    • D.

      Using the universal serial bus (USB) cable.

    Correct Answer
    A. Using an unshielded twisted-pair (UTP) cable.
    Explanation
    The preferred connection when connecting the cable modem to the customer's computer is using an unshielded twisted-pair (UTP) cable. This type of cable is commonly used for Ethernet connections and is designed to reduce electromagnetic interference. It is a reliable and cost-effective option for connecting the cable modem to the computer.

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  • 18. 

    What are some considerations when seeking a power source for the cable modem? 

    • A.

      The cable modem power supply should be plugged into a dedicated electrical outlet that will not be switched off and has no other appliances or devices plugged into it.

    • B.

      The cable modem power supply should be plugged into an electrical outlet that will not be switched off, near the customer's computer, and in a well-ventilated area so that it remains cool.

    • C.

      The cable modem power supply should be plugged into an electrical outlet that will not be switched off and because of its size is not likely to be unplugged.

    • D.

      The cable modem power supply should be plugged into an electrical outlet that will be switched off and because of its size is not likely to be unplugged.

    Correct Answer
    C. The cable modem power supply should be plugged into an electrical outlet that will not be switched off and because of its size is not likely to be unplugged.
    Explanation
    The cable modem power supply should be plugged into an electrical outlet that will not be switched off and because of its size is not likely to be unplugged. This is important because if the power source is switched off, the cable modem will lose power and the internet connection will be disrupted. Additionally, if the power supply is unplugged, the cable modem will also lose power. Therefore, it is necessary to have a dedicated electrical outlet that will remain on and ensure the cable modem stays connected to the power source.

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  • 19. 

    When a Data Over Cable Service Interface Specification (DOCSIS) modem is powered up and connected to the cable system it will automatically begin the initialization process. What is the first step to occur during the initialization process?

    • A.

      Scanning for downstream carrier.

    • B.

      Ranging.

    • C.

      Obtaining an IP address.

    • D.

      Downloading configuration data.

    Correct Answer
    A. Scanning for downstream carrier.
    Explanation
    The first step to occur during the initialization process of a DOCSIS modem is scanning for downstream carrier. This is because the modem needs to find and lock onto the downstream signal from the cable system before it can proceed with the rest of the initialization process, such as ranging, obtaining an IP address, and downloading configuration data.

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  • 20. 

    Why is it a good practice to reboot the customer's computer after you have successfully accessed an Internet site? 

    • A.

      Rebooting the computer ensures that the modem provisioning software installed on the computer remains in place.

    • B.

      Rebooting the computer confirms that any changed settings are stored in the computer's memory and that the computer and modem continue to operate together after rebooting.

    • C.

      Rebooting the computer prevents the unintentional downloading of modem-specific features into the customer's computer.

    • D.

      Rebooting the computer ensures that the modem installation client is installed in the customer's computer.

    Correct Answer
    B. Rebooting the computer confirms that any changed settings are stored in the computer's memory and that the computer and modem continue to operate together after rebooting.
    Explanation
    Rebooting the customer's computer after successfully accessing an Internet site is a good practice because it ensures that any changes made to the computer's settings are stored in its memory. This helps to maintain the proper functioning of the computer and modem as they continue to operate together after the reboot.

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  • 21. 

    Which of the following describes why the hybrid fiber/coax (HFC) return path design is especially sensitive to ingress and noise? 

    • A.

      Ingress and noise from each drop is filtered at each common point, affecting only the signals from that drop's customer premises equipment (CPE).

    • B.

      Ingress and noise from each drop is carried independently over fiber to the headend where the noise is filtered out.

    • C.

      Ingress and noise from multiple drops along a service area funnels into a common point, affecting all signals from that service area.

    • D.

      Ingress and noise from multiple drops funnels into multiple points along the return path, affecting just the signals from the first service area.

    Correct Answer
    C. Ingress and noise from multiple drops along a service area funnels into a common point, affecting all signals from that service area.
    Explanation
    In a hybrid fiber/coax (HFC) return path design, the ingress and noise from multiple drops along a service area all converge into a common point. This means that any ingress or noise from one drop can affect all signals from that entire service area. This sensitivity to ingress and noise is due to the fact that all the signals are funneled into a single point, making it more susceptible to interference.

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  • 22. 

    Which of the following device applications can be used in a system to reduce ingress noise? 

    • A.

      The use of a step attenuator or a high-pass filter on the combiner at the headend will block any noise generated on the drop in the return frequencies from entering the leg.

    • B.

      The use of a step attenuator between the drop and the cable modem will block any noise generated on the drop in the return frequencies from entering the leg.

    • C.

      The use of a diplex filter at the ground block will block any noise generated on the drop in the return frequencies from entering the leg.

    • D.

      The use of a high-pass filter at the tap will block any noise generated on the drop in the return frequencies from entering the leg.

    Correct Answer
    D. The use of a high-pass filter at the tap will block any noise generated on the drop in the return frequencies from entering the leg.
    Explanation
    Question #22: Multiple Choke - choose 1 answer (pg 3.8)
    Which of the following device applications can be used in a system to reduce ingress noise?
    A) The use of a step attenuator or a high-pass filter on the combiner at the headend will block any noise generated on the drop in the return frequencies from entering the leg.
    B) The use of a step attenuator between the drop and the cable modem will block any noise generated on the drop in the return frequencies from entering the leg.
    C) The use of a diplex filter at the ground block will block any noise generated on the drop in the return frequencies from entering the leg.
    D) The use of a high-pass filter at the tap will block any noise generated on the drop in the return frequencies from entering the leg.

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  • 23. 

    Where in the outside plant return path is one of the largest funnel points of RF return signals in the network? 

    • A.

      At the directional coupler of the drop farthest away from the node.

    • B.

      At the return amplifier farthest away from the node.

    • C.

      At the node.

    • D.

      At the tap farthest away from the node.

    Correct Answer
    C. At the node.
    Explanation
    At the node is the correct answer because the node is the central point where the RF return signals from all the drop cables converge. This convergence creates a funnel effect, making the node one of the largest funnel points for RF return signals in the network.

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  • 24. 

    Which of the following methods is employed to reduce traffic congestion on a hybrid fiber/coax (HFC) network? 

    • A.

      Installing separate drops for high-speed data (HSD), cable telephony, and cable television service.

    • B.

      Splitting the distribution legs into separate optical return paths.

    • C.

      Funneling in more distribution legs into a single optical node.

    • D.

      Reducing the number of cable modem termination system (CMTS) ports in the headend.

    Correct Answer
    B. Splitting the distribution legs into separate optical return paths.
    Explanation
    Splitting the distribution legs into separate optical return paths is a method employed to reduce traffic congestion on a hybrid fiber/coax (HFC) network. By separating the distribution legs, the network can handle more traffic and reduce congestion. This allows for better performance and faster speeds for high-speed data (HSD), cable telephony, and cable television service.

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  • 25. 

    Which of the following describes thermal noise? 

    • A.

      Thermal noise is always present in a transmission path and is created by the temperature fluctuations of the laser in an optical node.

    • B.

      Thermal noise is microwave ingress in a transmission path and is caused by local public safety radio transmissions.

    • C.

      Thermal noise is intermittent in a transmission path and is caused by the occasional electrical switching device like a motor or transformer.

    • D.

      Thermal noise is caused by fluctuations in electron density within amplifier circuitry. As the signal passes through an amplifier, thermal noise is generated and added to the amplified signal.

    Correct Answer
    D. Thermal noise is caused by fluctuations in electron density within amplifier circuitry. As the signal passes through an amplifier, thermal noise is generated and added to the amplified signal.
    Explanation
    Thermal noise is caused by fluctuations in electron density within amplifier circuitry. As the signal passes through an amplifier, thermal noise is generated and added to the amplified signal. This means that the noise is inherent to the system and is not caused by external factors such as temperature fluctuations or radio transmissions.

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  • 26. 

    Which of the following describes the methods used to determine if a set-top box (STB) is non-responsive? 

    • A.

      STBs are always in communications with the headend. A non-responsive STB generates an e-mail alert.

    • B.

      STBs send a status message to the cable modem to let it know when it loses contact with the headend.

    • C.

      STBs are polled to see if they respond and a report is created. Non-responsive STBs can result in a significant loss of revenue.

    • D.

      STBs are polled by the EMTA periodically to see if they respond. Non-responsive SIGs are replaced.

    Correct Answer
    C. STBs are polled to see if they respond and a report is created. Non-responsive STBs can result in a significant loss of revenue.
    Explanation
    STBs are polled to see if they respond and a report is created. This method is used to determine if a set-top box (STB) is non-responsive. Non-responsive STBs can result in a significant loss of revenue, so it is important to monitor their responsiveness. By polling the STBs and creating a report, it allows for easy identification of any non-responsive STBs, allowing for prompt action to be taken to address the issue and minimize revenue loss.

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  • 27. 

    Which of the following devices is the best choice when trying to isolate the cause of cable telephony or high-speed data (HSD) cable modem performance problems? 

    • A.

      A ground fault detector can easily isolate the cause of cable telephony or HSD cable modem problems in the drop system.

    • B.

      A modem emulator function in a signal level meter (SLM) can aid in troubleshooting the cause of cable telephony or HSD cable modem problems in the drop system.

    • C.

      A digital multimeter (DMM) can easily isolate the cause of cable telephony or HSD cable modem problems in the drop system.

    • D.

      A return path tester can be used to easily isolate the cause of cable telephony or HSD cable modem problems in the drop system.

    Correct Answer
    B. A modem emulator function in a signal level meter (SLM) can aid in troubleshooting the cause of cable telephony or HSD cable modem problems in the drop system.
    Explanation
    A modem emulator function in a signal level meter (SLM) can aid in troubleshooting cable telephony or high-speed data (HSD) cable modem problems in the drop system. This device can simulate the behavior of a cable modem, allowing technicians to test and diagnose potential issues without actually connecting a real modem. By using the modem emulator function, technicians can isolate the cause of the problems and determine if it is related to the cable modem or other factors in the system. This helps in efficiently identifying and resolving performance issues in cable telephony or HSD cable modem systems.

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  • 28. 

    When aligning the return amplifiers, which method will deliver the most accurate alignment results? 

    • A.

      A forward sweep from 54-860 MHz will deliver the most accurate alignment results.

    • B.

      A return sweep from 5-42 MHz will deliver the most accurate alignment results.

    • C.

      Injecting RF frequencies from 5-108 MHz at 6 MHz intervals will deliver the most accurate alignment results.

    • D.

      Injecting RF frequencies from 5-42 MHz at 6 MHz intervals will deliver the most accurate alignment results.

    Correct Answer
    B. A return sweep from 5-42 MHz will deliver the most accurate alignment results.
    Explanation
    A return sweep from 5-42 MHz will deliver the most accurate alignment results because it covers a narrower frequency range compared to the other options. This allows for a more focused and precise alignment process, ensuring that the return amplifiers are properly calibrated within this specific frequency range. The narrower range also reduces the potential for interference or signal distortion that may occur when aligning over a wider frequency range.

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  • 29. 

    The zero span and max hold features of a spectrum analyzer allow accurate measurement of which of the following impairments? 

    • A.

      Service interruptions from laser clipping.

    • B.

      Fluctuations in thermal noise.

    • C.

      Six MHz intermodulation beats due to common path distortion.

    • D.

      Fast transient signals such as impulse noise.

    Correct Answer
    D. Fast transient signals such as impulse noise.
    Explanation
    The zero span and max hold features of a spectrum analyzer allow accurate measurement of fast transient signals such as impulse noise. These features freeze the display and capture the maximum signal level, allowing the user to analyze and measure the characteristics of these transient signals. This is useful in identifying and troubleshooting issues related to impulse noise in a system.

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  • 30. 

    Which of the following devices have diagnostic pages which can be used to confirm and verify operation of the return path? 

    • A.

      Most cable modems, test generators, and set-top boxes (STB) have diagnostic pages.

    • B.

      Most leakage detectors, cable emulators, and return path testers have diagnostic pages.

    • C.

      Most cable modems, embedded multimedia terminal adapters (EMTA), and set-top boxes (STB) have diagnostic pages.

    • D.

      Most leakage detectors, cable emulators, and test generators have diagnostic pages.

    Correct Answer
    C. Most cable modems, embedded multimedia terminal adapters (EMTA), and set-top boxes (STB) have diagnostic pages.
    Explanation
    The correct answer is that most cable modems, embedded multimedia terminal adapters (EMTA), and set-top boxes (STB) have diagnostic pages. This means that these devices can be used to confirm and verify the operation of the return path.

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  • 31. 

    Which of the following describes the primary source of attenuation in the return path? 

    • A.

      Attenuation in the return path is primarily due to fiber-optic cable.

    • B.

      Attenuation in the return path is primarily due to the coaxial cable.

    • C.

      Attenuation in the return path is primarily due to the passive devices.

    • D.

      Attenuation in the return path is primarily due to the active devices.

    Correct Answer
    C. Attenuation in the return path is primarily due to the passive devices.
    Explanation
    Question #31: Multiple Choice - choose 1 answer (page 4.7)
    Which of the following describes the primary source of attenuation in the return path?
    A) Attenuation in the return path is primarily due to fiber-optic cable.
    B) Attenuation in the return path is primarily due to the coaxial cable.
    C) Attenuation in the return path is primarily due to the passive devices.
    D) Attenuation in the return path is primarily due to the active devices.

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  • 32. 

    Which of the following describes long-loop automatic gain control (AGC)? 

    • A.

      Long-loop AGC adjusts the transmit levels of the customer premises equipment.

    • B.

      Long-loop AGC adjusts the receive levels of the customer premises equipment.

    • C.

      Long-loop AGC adjusts the transmit levels from the headend to the customer premises equipment.

    • D.

      Long-loop AGC adjusts the receive levels from the headend to the customer premises equipment.

    Correct Answer
    A. Long-loop AGC adjusts the transmit levels of the customer premises equipment.
    Explanation
    Long-loop automatic gain control (AGC) is a mechanism that adjusts the transmit levels of the customer premises equipment. This means that it regulates the power of the signal being sent from the customer premises equipment to ensure that it is at an optimal level. By adjusting the transmit levels, long-loop AGC helps to maintain a consistent and reliable signal quality for communication between the customer premises equipment and the network.

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  • 33. 

    The use of a directional coupler requires which of the following adjustments in the return paths? 

    • A.

      Each return amplifier must be adjusted so that the levels received at the next amplifier are 25 dBmV.

    • B.

      The output of each return amplifier must be adjusted so that the input levels received at the next amplifier are the same.

    • C.

      Each return amplifier must be adjusted by the decibel (dB) value of the directional coupler (DC).

    • D.

      Each return amplifier must be adjusted so that the levels received at the next amplifier are within 15 dB of each other.

    Correct Answer
    B. The output of each return amplifier must be adjusted so that the input levels received at the next amplifier are the same.
    Explanation
    Each return amplifier must be adjusted so that the input levels received at the next amplifier are the same. This is because a directional coupler is used to split the signal between the main path and the return path. In order to ensure proper signal transmission, the input levels at each amplifier in the return path must be balanced and consistent. Adjusting the output of each return amplifier to match the input levels at the next amplifier ensures that the signal is properly distributed and avoids any signal loss or distortion.

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  • 34. 

    Which of the following describes the typical sub-band return frequency design for a cable modem? 

    • A.

      Most cable modems are configured to operate above 38 and below 42 MHz.

    • B.

      Most cable modems are configured to operate above 5 and below 20 MHz.

    • C.

      Most cable modems are configured to operate above 38 and below 54 MHz.

    • D.

      Most cable modems are configured to operate above 28 and below 38 MHz.

    Correct Answer
    D. Most cable modems are configured to operate above 28 and below 38 MHz.
  • 35. 

    If the drop loss at the ground block is 3.2 dB and is connected to a three-way splitter's hot leg and then connected to the 9 dB leg of a directional coupler (DC), what will be the total return path loss? 

    • A.

      The drop cable loss is 3.2 dB plus 7.0 dB (the loss of a three-way splitter) plus 9 dB (DC loss), for a total of 19.2 dB in drop return path loss.

    • B.

      The drop cable loss is 3.2 dB minus 3.5 dB (the hot-leg loss of a three-way splitter) plus 9 dB (DC loss) for a total of 8.7 dB in drop return path loss.

    • C.

      The drop cable loss is 3.2 dB plus 3.5 dB (the hot-leg loss of a three-way splitter) plus 9 dB (DC loss), for a total of 15.7 dB in drop return path loss.

    • D.

      The drop cable loss is 3.2 dB plus 3.5 dB (the hot-leg loss of a three-way splitter) minus 9 dB (DC loss), for a total of -2.3dB in drop return path loss.

    Correct Answer
    C. The drop cable loss is 3.2 dB plus 3.5 dB (the hot-leg loss of a three-way splitter) plus 9 dB (DC loss), for a total of 15.7 dB in drop return path loss.
    Explanation
    The total return path loss is calculated by adding the drop cable loss (3.2 dB) to the hot-leg loss of a three-way splitter (3.5 dB) and the DC loss (9 dB). This gives a total of 15.7 dB in drop return path loss.

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  • 36. 

    What are some possible causes of signal reflections? 

    • A.

      Overloaded input levels to a house amplifier that are reflected back to their source.

    • B.

      The use of splitters instead of directional couplers in the drop system.

    • C.

      Unpowered house amplifiers that reflect signals back to their source.

    • D.

      Loose or bad connections at the tap or unterminated splitter ports in the drop system.

    Correct Answer
    D. Loose or bad connections at the tap or unterminated splitter ports in the drop system.
    Explanation
    Possible causes of signal reflections include loose or bad connections at the tap or unterminated splitter ports in the drop system. When there are loose or bad connections, the signal can bounce back instead of being properly transmitted, leading to signal reflections.

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  • 37. 

    Which of the following procedures will reduce impulse noise? 

    • A.

      Impulse noise can be reduced by transmitting power on the distribution amplifiers.

    • B.

      Impulse noise can be reduced by tightening all connections and installing 75 Q terminators on unused tap ports.

    • C.

      Impulse noise can be reduced by locating taps and splitters close to switching power supplies.

    • D.

      Impulse noise can be reduced by tightening all connections and installing 10 dB attenuator pads on all used tap ports.

    Correct Answer
    B. Impulse noise can be reduced by tightening all connections and installing 75 Q terminators on unused tap ports.
    Explanation
    Tightening all connections and installing 75 Q terminators on unused tap ports can reduce impulse noise. This is because loose connections can cause signal interference and create noise, while terminators on unused tap ports help to absorb and eliminate any unwanted signals or noise that may be present in the system. By implementing these measures, the overall quality and clarity of the signal can be improved, reducing the impact of impulse noise.

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  • 38. 

    The most common source of ingress and egress is located at which of the following points in the broadband cable network? 

    • A.

      At the coax interface on the node.

    • B.

      At the distribution amplifier.

    • C.

      The customer premises and the drop cable.

    • D.

      At the headend.

    Correct Answer
    C. The customer premises and the drop cable.
    Explanation
    The customer premises and the drop cable are the most common points of ingress and egress in the broadband cable network. This is because the customer premises is where the cable service is accessed and the drop cable is the physical connection between the network and the customer's location.

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  • 39. 

    Which of the following mitigation devices provide filtering on sub-split return frequencies as described? 

    • A.

      Window filters act on specific frequencies from 5-42 MHz.

    • B.

      Window filters act on specific frequencies above 5-42 MHz.

    • C.

      Step attenuators provide 100 dB of attenuation on frequencies from 5-42 MHz.

    • D.

      High-pass filters block all frequencies above 108 MHz.

    Correct Answer
    A. Window filters act on specific frequencies from 5-42 MHz.
    Explanation
    The correct answer is "Window filters act on specific frequencies from 5-42 MHz." This answer states that window filters are designed to work on frequencies within the range of 5-42 MHz. This implies that window filters provide filtering on sub-split return frequencies within this range.

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  • 40. 

    What is a common solution to impulse noise and ingress problems in the network where tap values are less than 17 dB? 

    • A.

      Replacing tap plates of 17 dB or less with higher value tap plates.

    • B.

      Installing high-pass filters on all unused tap ports.

    • C.

      Installing high-pass filters on tap ports that are 17 dB or less.

    • D.

      Installing terminators on all unused tap ports.

    Correct Answer
    D. Installing terminators on all unused tap ports.
    Explanation
    Installing terminators on all unused tap ports is a common solution to impulse noise and ingress problems in the network where tap values are less than 17 dB. Terminators help to absorb and eliminate any unwanted signals or noise that may be present on the unused tap ports, ensuring a cleaner and more reliable network signal. This solution is effective in reducing interference and improving the overall performance of the network.

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  • 41. 

    In a Data Over Cable Service Interface Specification (DOCSIS) network, why is the data throughput over the return or upstream path typically less than the throughput of data over the forward or downstream path?

    • A.

      Compared to the downstream path, the narrower bandwidths and lower orders of modulation used to transport data over the return path cause the downstream and upstream data throughput to be unequal or asymmetrical.

    • B.

      Compared to the downstream path, the narrower bandwidths and lower transmit power of the modems used to transmit data over the return path cause the downstream and upstream data throughput to be unequal or asymmetrical.

    • C.

      Compared to the downstream path, the narrower bandwidths and higher orders of modulation used to transport data over the return path cause the downstream and upstream data throughput to be unequal or asymmetrical.

    • D.

      Compared to the downstream path, the higher bandwidths and lower orders of modulation used to transport data over the return path cause the downstream and upstream data throughput to be unequal or asymmetrical.

    Correct Answer
    A. Compared to the downstream path, the narrower bandwidths and lower orders of modulation used to transport data over the return path cause the downstream and upstream data throughput to be unequal or asymmetrical.
    Explanation
    In a DOCSIS network, the data throughput over the return or upstream path is typically less than the throughput of data over the forward or downstream path because the narrower bandwidths and lower orders of modulation are used to transport data over the return path. This results in asymmetry in the downstream and upstream data throughput.

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  • 42. 

    What are three primary features of Data Over Cable Service Interface Specification (DOCSIS) version 3.0? 

    • A.

      Channel bonding, IP version 6 (IPv6) support, and enhanced use of IP broadcast.

    • B.

      Channel bonding, IP version 6 (IPv6) support, and enhanced use of IP multicast.

    • C.

      Channel bonding, IP version 6 (IPv6) support, and best effort delivery of IP multicast.

    • D.

      Channel bonding, IP version 6 (IPv6) support, and exclusive quality of service (QoS).

    Correct Answer
    B. Channel bonding, IP version 6 (IPv6) support, and enhanced use of IP multicast.
    Explanation
    The three primary features of DOCSIS version 3.0 are channel bonding, IP version 6 (IPv6) support, and enhanced use of IP multicast. Channel bonding allows for the aggregation of multiple channels to increase data throughput. IPv6 support enables the use of the newer version of the Internet Protocol, which allows for a larger number of unique IP addresses. Enhanced use of IP multicast improves the efficiency of data transmission by allowing for the simultaneous delivery of data to multiple recipients.

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  • 43. 

    What would be the downstream throughput if two 256-QAM channels with a throughput of 38 megabits per second (Mbps) were bonded? 

    • A.

      38 Mbps.

    • B.

      152 Mbps.

    • C.

      108 Mbps.

    • D.

      76 Mbps.

    Correct Answer
    D. 76 Mbps.
    Explanation
    When two 256-QAM channels are bonded, their throughputs do not simply add up. Instead, the throughput is limited by the channel with the lower throughput. In this case, both channels have a throughput of 38 Mbps, so the maximum downstream throughput when they are bonded would also be 38 Mbps. Therefore, the correct answer is 38 Mbps, not 76 Mbps.

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  • 44. 

    What Internet protocol (IP) address modes can a Data Over Cable Service Interface Specification (DOCSIS) 3.0 modem be provisioned in? 

    • A.

      IP version 4 (IPv4), IP version 6 (IPv6), dynamic host configuration protocol (DHCP), and dual-stack mode (DPM).

    • B.

      IP version 4 (IPv4), IP version 6 (IPv6), alternate provisioning mode (APM), and dual-stack mode (DPM).

    • C.

      IP version 4 (IPv4), IP version 6 (IPv6), alternate provisioning mode (APM), and dynamic host configuration protocol (DHCP).

    • D.

      IP version 4 (IPv4), IP version 6 (IPv6), IP multicast, and dual-stack mode (DPM).

    Correct Answer
    B. IP version 4 (IPv4), IP version 6 (IPv6), alternate provisioning mode (APM), and dual-stack mode (DPM).
    Explanation
    A Data Over Cable Service Interface Specification (DOCSIS) 3.0 modem can be provisioned in IP version 4 (IPv4), IP version 6 (IPv6), alternate provisioning mode (APM), and dual-stack mode (DPM). This means that the modem can support both IPv4 and IPv6 protocols, as well as different provisioning modes such as APM and DPM. The inclusion of dual-stack mode allows the modem to handle both IPv4 and IPv6 traffic simultaneously.

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  • 45. 

    How does IP multicast differ from IP broadcast?

    • A.

      IP multicast traffic is only sent to specific modem addresses on the network; IP broadcast traffic is sent to all modems on the network.

    • B.

      IP multicast traffic is only sent to one modem at a time on the network; IP broadcast traffic is sent to all modems on the network all the time.

    • C.

      IP multicast traffic is sent to all modems on the network; IP broadcast traffic is only sent to specific modem addresses on the network.

    • D.

      IP multicast traffic is only sent to a maximum of 100 modem addresses on the network; IP broadcast traffic is sent to all modems on the network.

    Correct Answer
    A. IP multicast traffic is only sent to specific modem addresses on the network; IP broadcast traffic is sent to all modems on the network.
    Explanation
    IP multicast traffic is different from IP broadcast traffic because multicast traffic is only sent to specific modem addresses on the network, while broadcast traffic is sent to all modems on the network. This means that multicast traffic is targeted and intended for a specific group of recipients, whereas broadcast traffic is intended for all devices on the network.

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  • 46. 

    Where is a logical place to begin troubleshooting a high-speed data (HSD) problem in the customer premises? 

    • A.

      The ground block.

    • B.

      The network interface card (NIC) in the customer's computer.

    • C.

      The cable modem.

    • D.

      The customer's wireless router.

    Correct Answer
    C. The cable modem.
    Explanation
    The cable modem is a logical place to begin troubleshooting a high-speed data (HSD) problem in the customer premises because it is responsible for establishing the connection between the customer's computer and the internet service provider. If there is an issue with the cable modem, such as a faulty connection or a configuration problem, it can result in a loss of internet connectivity. Therefore, checking the cable modem would be the first step in identifying and resolving the HSD problem.

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  • 47. 

    Why is data throughput an effective measurement of the network's technical integrity? 

    • A.

      Because data throughput is an obscure measurement that the customer is unable to relate to their service.

    • B.

      Because the data throughput measurement is derived from data packets traveling downstream only, separating downstream issues from upstream issues.

    • C.

      Because data throughput is an easy measurement that can be accurately obtained by the customer going to a generic speed test site on the Internet.

    • D.

      Because data throughput can be compromised by traffic congestion and errors introduced during transport through the network.

    Correct Answer
    D. Because data throughput can be compromised by traffic congestion and errors introduced during transport through the network.
    Explanation
    Data throughput is an effective measurement of the network's technical integrity because it reflects the actual speed at which data is being transferred through the network. It takes into account factors such as traffic congestion and errors during transport, which can significantly impact the network's performance. By monitoring data throughput, network administrators can identify and address any issues that may be affecting the network's efficiency and reliability.

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  • 48. 

    When using a digital signal analyzer to troubleshoot data throughput in the Data Over Cable Service Interface Specification (DOCSIS) network, what is the minimum modulation error ratio (MER) into the cable modem for a 256-QAM carrier? 

    • A.

      26 dB or less.

    • B.

      32 dB or greater.

    • C.

      32 dB or less.

    • D.

      26 dB or greater.

    Correct Answer
    B. 32 dB or greater.
    Explanation
    The minimum modulation error ratio (MER) into the cable modem for a 256-QAM carrier in the DOCSIS network is 32 dB or greater. This means that the MER value should be at least 32 dB or higher for proper data throughput. A higher MER indicates better signal quality and less error in the modulation. Therefore, a minimum of 32 dB or greater is required to ensure reliable data transmission in the DOCSIS network.

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  • 49. 

    How is the data throughput of the hybrid fiber/coax (HFC) network most accurately measured?

    • A.

      From the customer's computer to the throughput server that is connected to the cable modem termination system (CMTS) in the headend or hub.

    • B.

      From the customer's computer to a Web site server on the Internet.

    • C.

      From the customer's computer to a speed test Web site on the Internet.

    • D.

      From the customer's computer to a special cable modem located in the headend or hub.

    Correct Answer
    A. From the customer's computer to the throughput server that is connected to the cable modem termination system (CMTS) in the headend or hub.
    Explanation
    The data throughput of the hybrid fiber/coax (HFC) network is most accurately measured from the customer's computer to the throughput server that is connected to the cable modem termination system (CMTS) in the headend or hub. This is because the CMTS is the central point where the network connects to the internet and where the data transmission is managed. By measuring the throughput from the customer's computer to this server, it provides an accurate representation of the network's performance and the actual data speed experienced by the customer.

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  • 50. 

    Of the four Internet protocol (IP) provisioning modes available in Data Over Cable Service Interface Specification (DOCSIS) 3.0, which are designed to provide a smooth transition from IP version 4 (IPv4) to IP version 6 (IPv6)? 

    • A.

      Dynamic host configuration provisioning (DHCP) and dual-stack provisioning mode (DPM).

    • B.

      Alternate provisioning mode (APM) and multistack provisioning mode (MPM).

    • C.

      Alternate provisioning mode (APM) and dual-stack provisioning mode (DPM).

    • D.

      Alternate provisioning mode (APM) and dynamic host configuration protocol (DHCP) mode.

    Correct Answer
    C. Alternate provisioning mode (APM) and dual-stack provisioning mode (DPM).

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  • Current Version
  • Jul 19, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Jan 04, 2016
    Quiz Created by
    Clash55789
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