Data Over Cable Service Interface Specification Quiz

90 Questions | Total Attempts: 169

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Data Communication Quizzes & Trivia

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).

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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).

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

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