,COMPREHENSIVE NCTI QUESTIONS AND ANSWERS
GRADED A+
◉ What are two features that were added in Data Over Cable Service
Interface Specification(DOCSIS) 3.1 to extend the viability of hybrid
fiber/coax(HFC) network into the next decade. Answer: Orthogonal
frequency division multiplexing(OFDM) and low-density paritycheck
(LDPC)
◉ How does Internet Protocol (IP) multicast differ from IP
broadcast. Answer: IP multicast traffic is only sent to specific
modem addresses on the network; IP broadcast traffic is sent to all
modems on the network
◉ Which step in the troubleshooting process requires a discussion
with the customer to gather more detail about the problem. Answer:
Step 1: Identify the Problem
◉ When analyzing a problem, what can the technician learn by
asking the customer to show or demonstrate the problem. Answer:
The symptoms of the problem can be viewed and any unusual
screens or customer entries can be identified
◉ 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-quadrature amplitude
modulation(QAM) carrier. Answer: 32 dB or greater
, ◉ What layers of the Open Systems Interconnection (OSI) reference
model are specific to cable networks and are present only between
Data Over Cable Service Interface Specification (DOCSIS) modems
and the cable modem termination system (CMTS)?. Answer: Layers
1 through 4 (Physical layer, Data Link Layer, Network Layer, and
Transport Layer) are applied between the DOCSIS modem and CMTS
◉ A customer reports a problem of no dial tone(NDT) Upon
Inspection, the tech notices that new carpenting has been installed.
What should the tech do next. Answer: Look for a cable that runs
under the carpet; it is likely that the cable has a short from the
carpeting tack strip
◉ What is the likely problem when there is dial tone on one phone
connected to an outlet, but not on two other phones connected to
two different outlets. Answer: An open circuit caused by a break in a
conductor, poor contact in a modular connector, or an incorrect wire
connection
◉ In the customer premises, what could cause some dual tone
multifrequency (DTMF) touch-tone telephones to have continuous
dial tone caused by polarity reversal, but not other DTMF
telephones. Answer: The telephone wiring polarity is incorrect, and
the customer has a mix of older and newer DTMF touch-tone
telephones
GRADED A+
◉ What are two features that were added in Data Over Cable Service
Interface Specification(DOCSIS) 3.1 to extend the viability of hybrid
fiber/coax(HFC) network into the next decade. Answer: Orthogonal
frequency division multiplexing(OFDM) and low-density paritycheck
(LDPC)
◉ How does Internet Protocol (IP) multicast differ from IP
broadcast. Answer: IP multicast traffic is only sent to specific
modem addresses on the network; IP broadcast traffic is sent to all
modems on the network
◉ Which step in the troubleshooting process requires a discussion
with the customer to gather more detail about the problem. Answer:
Step 1: Identify the Problem
◉ When analyzing a problem, what can the technician learn by
asking the customer to show or demonstrate the problem. Answer:
The symptoms of the problem can be viewed and any unusual
screens or customer entries can be identified
◉ 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-quadrature amplitude
modulation(QAM) carrier. Answer: 32 dB or greater
, ◉ What layers of the Open Systems Interconnection (OSI) reference
model are specific to cable networks and are present only between
Data Over Cable Service Interface Specification (DOCSIS) modems
and the cable modem termination system (CMTS)?. Answer: Layers
1 through 4 (Physical layer, Data Link Layer, Network Layer, and
Transport Layer) are applied between the DOCSIS modem and CMTS
◉ A customer reports a problem of no dial tone(NDT) Upon
Inspection, the tech notices that new carpenting has been installed.
What should the tech do next. Answer: Look for a cable that runs
under the carpet; it is likely that the cable has a short from the
carpeting tack strip
◉ What is the likely problem when there is dial tone on one phone
connected to an outlet, but not on two other phones connected to
two different outlets. Answer: An open circuit caused by a break in a
conductor, poor contact in a modular connector, or an incorrect wire
connection
◉ In the customer premises, what could cause some dual tone
multifrequency (DTMF) touch-tone telephones to have continuous
dial tone caused by polarity reversal, but not other DTMF
telephones. Answer: The telephone wiring polarity is incorrect, and
the customer has a mix of older and newer DTMF touch-tone
telephones
