Data Over Cable Service Interface Specification Quiz

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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. 
    • 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. 
    • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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).

  • 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.

  • 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).

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 51. 
    Which of the following statements is true regarding the wireless industry? 
    • A. 

      It is evolving quickly and rather unpredictably as the products and services are changing.

    • B. 

      It has no set of competing standards for communications protocols, interfaces, and networks.

    • C. 

      It only uses visible light waves to carry a signal through atmospheric space rather than along a wire.

    • D. 

      It has appeal because all frequencies do not require any form of licensing by the Federal Communications Commission.

  • 52. 
    The cellular network 
    • A. 

      Since 1969 exclusively has used a simplex mode of operation and manual call placement.

    • B. 

      Uses a base station consisting of a transmitter, receiver, controller, and an antenna system and has a wired link to a mobile switching center (MSC).

    • C. 

      Is any mobile communications network with a series of overlapping hexagonal cells in a honeycomb pattern.

    • D. 

      Began with the advanced mobile phone service (AMPS) that was introduced in the United States in 1993.

  • 53. 
    In a cellular phone system, 
    • A. 

      Typically, every seventh cell uses the same set of frequencies.

    • B. 

      Cells use an unlimited number of transmission frequencies.

    • C. 

      The base station hands off the call to the mobile switching center in the next cell into which the user is traveling.

    • D. 

      Two cells can use the same frequency for different conversations as long as the cells are adjacent to each other.

  • 54. 
    Which of the following is one mode of wireless access? 
    • A. 

      Analog CDMA technology.

    • B. 

      Analog TDMA technology.

    • C. 

      Digital CDMA technology.

    • D. 

      Digital FDMA technology.

  • 55. 
    Digital FDMA technology. 
    • A. 

      Can carry data along with voice by digitizing the voice, expanding it, and then transmitting the voice interspersed with other conversations.

    • B. 

      Was rejected as the access technique for the global system for mobile communications (GSM) system.

    • C. 

      Allocates only two time slots per 30 kHz channel.

    • D. 

      Digital technology is designed to coexist with the analog AMPS.

  • 56. 
    Which of the following is true about cellular technologies?
    • A. 

      CDMA spread spectrum technology separates users by assigning them digital codes within the available frequency.

    • B. 

      CDMA makes it easy for hackers to grab orderly, meaningful data and does not ensure secure communications.

    • C. 

      FDMA divides the frequency spectrum into time slots, and TDMA divides the frequency spectrum into frequency slots.

    • D. 

      CDMA has the same capacity of TDMA but nearly 10 times that of FDMA.

  • 57. 
    Wireless applications 
    • A. 

      And equipment include cellular phones, pagers, cordless phones, cordless laptops, palmtops, computer peripheral devices, home entertainment control systems, and other products.

    • B. 

      Require a minimum bit rate of 10 kbps to satisfy intersystem matching between wireless and wired LANs.

    • C. 

      Using wireless local area network technology can offer substantially higher data rates by increasing the size of the coverage area.

    • D. 

      Using cordless and wireless local area network (WLAN) technology have higher mobility and higher cost than cellular systems.

  • 58. 
    Wireless local area networks (WLANs) 
    • A. 

      Are more reliable than wired LANs; error rates are lower when compared with wired media.

    • B. 

      Are regulated by the IEEE 802.11 standard, which defines some common features for connectivity on the 2.4 GHz licensed radio band.

    • C. 

      Have the exact same physical medium as the wired media; both are shared and have limited point-to-point connection ranges.

    • D. 

      Are flexible communications systems implemented as extensions to or as alternatives for the wired LANs in buildings or on campuses.

  • 59. 
    Microwave-based local area networks 
    • A. 

      Are available in analog and digital system configurations, with analog configurations dominating the current products.

    • B. 

      Must use line-of-sight for the transmit/receive antennas, which cannot be more than about 30 miles apart.

    • C. 

      Are not affected by atmospheric conditions such as rain and humidity.

    • D. 

      Using digital technology consist of four major components on both sides of the link: modem, RF unit, waveguide, and an antenna.

  • 60. 
    A communications satellite 
    • A. 

      Contains 42 translators, which are similar to transceivers, each a dedicated communications channel.

    • B. 

      Has a translator that receives a signal from an earth station, amplifies the signal, changes its frequency, and then retransmits the signal back to Earth.

    • C. 

      Operating at low earth orbit (LEO) is traveling at an elevation between 1,800 and 6,500 miles.

    • D. 

      Operating at a geostationary orbit (GEO) is traveling above the equator at an altitude of 22,300 miles.

  • 61. 
    The high-level data link control (HDLC) frame format 
    • A. 

      Uses five bytes (24 bits) of control information to describe the type of HDLC frame, routing parameters, and other packet identifiers.

    • B. 

      Is specified as the standard protocol for Layer 15 in the OSI model.

    • C. 

      Consists of raw data or information and an overhead that envelops the raw data.

    • D. 

      Allows every device to send (but not receive) information without being controlled by any other device.

  • 62. 
    In the client/server network, 
    • A. 

      Some hardware and software, such as the network interface card (NIC) and the network drivers, reside in the server.

    • B. 

      The software that interacts between an application and a network is defined as client software.

    • C. 

      The network operating system (NOS) software resides on a computer called the "server."

    • D. 

      The cost of hardware maintenance is significantly increased because the client machines are more complex and expensive.

  • 63. 
    A local area network (LAN) 
    • A. 

      Uses the bus topology to put the secondary station in control of all communication on the bus.

    • B. 

      Uses the star topology to place the secondary station at the center, allowing connection to all primary stations.

    • C. 

      Uses the peer-to-peer bus topology to enable any station to initiate communication with any other station through a primary station.

    • D. 

      Uses the ring topology to eliminate the problems with contention found on peer-to-peer bus networks.

  • 64. 
    In the token-passing process, 
    • A. 

      Each station receives and then regenerates the token.

    • B. 

      Network access is disorderly and response time is unpredictable.

    • C. 

      If any station or node goes down, the entire network collapses only when bypass software is used.

    • D. 

      When the addressed station receives the data, it cannot modify the packet's control field.

  • 65. 
    In the contention-based carrier sense multiple access with collision detection (CSMA/CD) system, 
    • A. 

      Any of the network devices can transmit data onto the network at will; there is no central controller.

    • B. 

      Stations are unable to listen to the network to hear if it is in use before they send data.

    • C. 

      An interface can transmit when another one is transmitting, a technique called carrier sensing.

    • D. 

      The response time is predictable under conditions of a heavily loaded system.

  • 66. 
    Which of these statements is true about LAN technologies?
    • A. 

      The most common baseband LAN technologies are token bus, token ring, fiber distributed data interface, and Ethernet.

    • B. 

      Token ring is a 4 or 16 Mbps ring-architectured system, which uses a token-passing access method with unpredictable response time under all loads.

    • C. 

      FDDI stations are connected in a dual bus with fiber-optic cable, and the LAN uses the token-passing concept but operating at a slower speed.

    • D. 

      Ethernet is a star-architectured broadband system in which each physical link uses a shared media access control (MAC)-addressed port.

  • 67. 
    In Ethernet LAN configurations, 
    • A. 

      The system is described as a heavy-duty network because as the number of hosts increase, the share each gets of the total available bandwidth increases.

    • B. 

      The 10BaseT supports a 100 Mbps transmission rate and uses a bus topology, which is implemented by a hub or wiring concentrator.

    • C. 

      Gigabit Ethernet can operate over fiber-optic, CAT-5 UTP, and coaxial cabling, typically.

    • D. 

      The 100BaseT standard does not support applications and networking software running on 10BaseT networks.

  • 68. 
    Switches 
    • A. 

      Are transceivers that receive, amplify, and retransmit information.

    • B. 

      Are being replaced by hubs and routers as the dominant form of internetworking.

    • C. 

      Establish point-to-point connection between ports at the full wire speed of the network.

    • D. 

      Have the ability to filter out and block unwanted or unauthorized traffic.

  • 69. 
    Which of the following statements is true? 
    • A. 

      A packet will travel through only one network point with a router before arriving at its destination.

    • B. 

      Router performance is measured by its packet-forwarding rate.

    • C. 

      The gateway is processor-intensive, and the device is designed to link only compatible networks.

    • D. 

      A router is a network bridge combined with a switch.

  • 70. 
    In trunking, 
    • A. 

      Four fast Ethernet ports can be trunked to work only like one big 20 Mbps pipe.

    • B. 

      A Layer 2 switch is used as a trunk port.

    • C. 

      A networking device bonds multiple physical links into a group that works like one logical link.

    • D. 

      A computing device such as a server or desktop computer cannot be used.

  • 71. 
    In packet-switching networks, 
    • A. 

      The frame relay layer establishes logical channels and a virtual circuit from each source to each destination.

    • B. 

      Each packet contains all of the necessary control and routing information to deliver the packet across the network.

    • C. 

      A packet connects two sites, the same as a leased line, except the bandwidth is shared.

    • D. 

      Analog circuits deliver error performance of at least 10-9 and often better.

  • 72. 
    Which statement is true for frame relay? 
    • A. 

      Frame relay uses error checking at every node and continual message exchange regarding the progress of packets.

    • B. 

      Frame relay uses a technique called distributed queue on a dual bus, which distributes the network requests of users into queues to handle information transfer.

    • C. 

      Frame relay was designed to ensure guaranteed data delivery and integrity because its circuits have analog error rates of 10-sto 10-6.

    • D. 

      Each node on the network only checks the address but never verifies the payload and passes the frame along a predetermined path.

  • 73. 
    What is committed information rate (CIR)? 
    • A. 

      Is a guaranteed rate of throughput when using frame relay.

    • B. 

      Is based on five classes of service, which provides control over how much information a node can place on the network.

    • C. 

      Is equal to total throughput added to the Br and Be values.

    • D. 

      Is not allowed by some carriers, who limit the maximum throughput to the bursting rate.

  • 74. 
    In ISDN, which of the following is true regarding the basic rate interface (BRI)?
    • A. 

      The BRI is appropriate for a business that utilizes a T-1 line, since it offers an economic alternative for connecting analog PBXs, LANs, and other devices to the network.

    • B. 

      The BRI uses one "B" channel and 23 "D" channels, all at 128 kbps, yielding a 1.544 Mbps line.

    • C. 

      The BRI is a "2B+D" interface, with two 64 kbps bearer ("B") channels that can carry voice, data or video, and one 16 kbps data ("D") channel that provides intelligent line management.

    • D. 

      The phone company replaces the basic rate interface (BRI) circuit with a conventional analog circuit.

  • 75. 
    Synchronous optical network (SONET)
    • A. 

      Defines the properties of an optical bit stream that specify the characteristics of optical fiber, which allow data to move across the medium.

    • B. 

      Is based upon half the fundamental rate of 150 Mbps.

    • C. 

      Is identical to synchronous digital hierarchy.

    • D. 

      Cannot be installed over fiber because it was designed to operate over copper cable by ensuring interoperability.

  • 76. 
    Which statement is true for asynchronous transfer mode (ATM)? 
    • A. 

      The ATM layer adds a 53-byte header with connection and QoS information to each cell and passes the cell to the application layer.

    • B. 

      An ATM cell consists of 155 8-bit bytes, with the 155-byte cell size resulting from a compromise between voice and video communications.

    • C. 

      ATM is a connectionless protocol that requires a single virtual path to be set up for all flows.

    • D. 

      ATM's ability to create virtual paths and channels means that multiple customers' traffic can be carried on a single network without security concerns or encryption overhead.

  • 77. 
    Asynchronous transfer mode (ATM) 
    • A. 

      Cannot accept real-time traffic, such as voice and video, because it introduces too much latency and jitter while serving as a statistical multiplexer.

    • B. 

      Provides seven service classes, one for each layer of the OSI.

    • C. 

      Will give traffic access to a virtual circuit regardless of whether a contracted Qo5 standard can be ensured.

    • D. 

      Cells consisting of 53 bytes are too small for efficient data transfer since a minimum IP data packet is 64 bytes.

  • 78. 
    Packet over SONET 
    • A. 

      Requires ATM to map IP packets directly onto SONET frames.

    • B. 

      Makes a network that uses a combination of T-1 and T-3 lines for voice and data a prime candidate for redesign.

    • C. 

      Transfers packets with less efficiency of bandwidth than over ATM on an OC-3 link.

    • D. 

      Protocols are optimized for fixed-length packets rather than variable length ATM cells.

  • 79. 
    A digital subscriber line (DSL) 
    • A. 

      Accommodates ordinary analog telephone calls over a different wire connection that uses the "D" channel.

    • B. 

      Cannot be implemented on most of the existing copper infrastructure.

    • C. 

      Supports a wide variety of high-bandwidth applications including virtual private networking and streaming multimedia content.

    • D. 

      Uses a line-sharing technique that is a simplified form of old-fashioned time division multiplexing.

  • 80. 
    An asynchronous transfer mode-passive optical network (ATM-PON) 
    • A. 

      Is an optical-access architecture that facilitates broadband communications over an active optical distribution network.

    • B. 

      Provides a dedicated optical connection that is secure all the way to the central office.

    • C. 

      Architecture has a minimum of 32 ONUs that can share the capacity of a single fiber using passive optical splitter/ combiner technology.

    • D. 

      Applies a framing structure to the upstream signals to support multimode operation.

  • 81. 
    Transmission control protocol/Internet protocol (TCP/IP) 
    • A. 

      Has become the least accepted set of protocols in the telecommunications industry.

    • B. 

      Was the result of a development effort to reach heterogeneous connectivity in packet-switched networks.

    • C. 

      Uses session and presentation layers for all of its standard services.

    • D. 

      Is a true international standard (not a de facto standard) for global educational and government industries.

  • 82. 
    Which of the following statements is true? 
    • A. 

      If reliability is ensured at a higher layer, such as the application layer, then UDP, which is less efficient than TCP, cannot be used for transport.

    • B. 

      TCP cannot be used with 051 Layer 3 protocols such as IP.

    • C. 

      In comparison with TCP, UDP is a reliable, connection- oriented protocol with more overhead.

    • D. 

      Connectionless means that a protocol does not require a session to be established between two devices, and transmission occurs on a best-effort basis.

  • 83. 
    Internet protocol (IP) 
    • A. 

      Consists of end-to-end error checking and acknowledgement, making it a highly reliable protocol.

    • B. 

      Segments and packetizes data for transmission and then applies a header for delivery.

    • C. 

      Headers include the source address but not the destination address, enabling an end-to-end data flow.

    • D. 

      Routing specifies that IP datagrams travel through internetworks with the entire route known at the outset of the journey.

  • 84. 
    Internet protocol version 4 (IPv4) 
    • A. 

      Multicast addressing for Class D networks is decreasing in usage because it consumes too much bandwidth.

    • B. 

      Addressing supports five different network classes, with the bits to the far left indicating the network class.

    • C. 

      Addressing requires a unique 48-bit address for each host on an IP-based network.

    • D. 

      Addresses for Class A networks are intended mainly for use with small networks, with a maximum of 200 Class A networks available.

  • 85. 
    Dotted decimal notation
    • A. 

      Divides a 32-bit IP address into four 8-bit (1-byte) fields, with the value of each field specified as a decimal number.

    • B. 

      Expresses IP addresses via the use of three-letter identifiers with "com" or "edu" endings separated by hyphens.

    • C. 

      IP addresses can be translated into meaningful and easy-to-remember domain names through the use of an EDU server.

    • D. 

      For Class A addresses sets the left-hand bit position in the first byte field to five.

  • 86. 
    The TCP/IP-based application 
    • A. 

      That sends standard, interoperable text messages from one computer system to another is called the simple mail transfer protocol.

    • B. 

      Post office protocol (POP) provides a store-and-forward mechanism that ensures clients connected to the network are able to retrieve e-mail via the Internet.

    • C. 

      FTP can tolerate packet loss, but TELNET cannot because it is bandwidth-intensive.

    • D. 

      Known as point-to-point protocol (PPP) was designed to route a single protocol over always-on links through point-to-point separations.

  • 87. 
    Virtual private networks (VPNs)
    • A. 

      Maintain the privacy of communications mainly by encrypting and tunneling the data forwarded between sites.

    • B. 

      Continue the connection between locations even after the transmission session is terminated.

    • C. 

      Are characterized by connections that occur between point-to-point secure clients and are controlled by hardware and switching made prior to the connection.

    • D. 

      Are static and maintain permanent links between the end-points that make up the corporate network.

  • 88. 
    The converged data/voice network 
    • A. 

      Solutions need not accommodate features such as automatic attendant capability, teleconferencing, or caller ID.

    • B. 

      Fulfills all but the most fundamental aspect of network management of integrating the transport of information cost-effectively.

    • C. 

      Uses a variety of hardware and software products for voice digitization and compression that enable voice to be transported on public and private networks originally developed to transport data.

    • D. 

      Is required to treat different data types exactly alike and must have high delay for voice telephony, megabit data streams for video, and high error rates for mission-critical data.

  • 89. 
    The voice over IP (VoIP) 
    • A. 

      Resource reservation protocol lets all applications share a path across an IP network, even when resources are inadequate to provide the required level of service.

    • B. 

      Real-time transport protocol is implemented in applications that do not need much bandwidth, but is unable to compensate for any packet loss.

    • C. 

      H.323 protocol is the recommended standard for multimedia transmission on wide area and packet networks that have a guaranteed bandwidth.

    • D. 

      Open settlement protocol involves a dedicated server to handle authentication, authorization, call routing, and call detail over IP networks.

  • 90. 
    Quality of service in an IP network 
    • A. 

      Is the focus of two protocols, DiffServ and multiprotocol label switching.

    • B. 

      Is not affected by changes in network traffic load.

    • C. 

      Gives all packets equal priority in a congested network.

    • D. 

      Uses multiprotocol services switching, which works with IP, ATM, and frame relay protocols by forwarding packets at Layer 3 rather than Layer 2.